【讨论】由"转基因玉米惹祸 "引起的转基因食品安全的讨论
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今天看到"转基因玉米惹祸 "文章，想就此对转基因食品安全的问题从专业角度分析其真伪，望大家积极讨论参与。
附带转发"转基因玉米惹祸 "报道一篇，希望有些专业人士意见。
http://news.sina.com.cn/c/2010-09-22/100318149161s.shtml
转基因玉米惹祸
http://www.sina.com.cn 2010年09月22日10:03 大众网-齐鲁晚报
大老鼠消失、母猪爱生死胎、狗肚子里都是水，此外，羊也出现异常情况。全国闻名的生猪集散地，很多村子的养猪业已经变得萧条。而这些出现异常的动物，几乎都吃过同一种玉米———先玉335。美国的专利记录显示，中国大量种植的玉米种子“先玉335”的父本PH4CV的类别编号指示为转基因农作物。
一直深受鼠患之苦的山西晋中张庆乡农民刘旻(化名)，现在却为当地老鼠绝迹而感到不安。
刘旻家里种了十来亩玉米。“过去，家里的老鼠经常是蹿上蹿下的，需要买剧毒鼠药，从3年前开始，我突然发现即使不放老鼠药，也少有老鼠吃家里东西了。”刘旻说。
为此，刘旻开始观察了解村里的老鼠情况，情况大同小异:大老鼠基本绝迹，只有一些小老鼠，看上去也是呆头呆脑的。
今年5月，记者在晋中8个村庄走访，进一步印证了刘旻所说的动物异常情况。许多村民都证实“老鼠变少了”，尤其是不见大老鼠。
远在吉林省榆树市秀水镇苏家村的于彦辉有着同样的困惑。他发现最近三年以来，庄稼地里的老鼠突然没了，“以前那些老鼠专门啃玉米棒，要放很多老鼠药;现在村民打完的玉米堆放在地里，也没有老鼠跑来吃。”
对于老鼠为何减少，村民陈陶陪认为是因为三四年前榆树市里曾统一在地里放药，另外的原因则是老鼠的天敌比如黄鼠狼、老鹰多了。
不过，他还是有些困惑，以前也有老鼠的天敌，为何那时老鼠那么多。“也可能是生态环境改变的原因。”
但是，儿名村民均表示最近儿年村庄周围没有影响生态环境的因素，除了周边建了两个砖厂外，没有建其他企业，更没有什么废水污染物排出。
猪肚里都是水
从5月到8月，记者儿次在晋中和榆树附近的农村走访调查老鼠变少的情况，却发现了当地另外的怪事:母猪产子少了，不育、假育、流产的情况比较多。
养猪户张健红养猪快十年了，他说，以前他家养的20多头母猪，一窝猪最多能生16只，从来没有低过10只的。也就是在4年前，他发现母猪生的小猪越来越少。
“有时只有六七只，总之这儿年生的小猪没有上过10头的。”他
还反映说，自己家里同时养了儿十头肥猪，生长的速度明显比前儿年放慢。这儿年养猪一直亏本的他不得不先后卖掉了十儿只母猪。“我把剩下的儿只猪卖完就不再养了。”张健红说。
苏家村的养猪户陈红军也遇到了类似的情况。由于最近三年，猪死胎、流产的现象较多，让他至少损失了1/3的小猪。村里不少的个体养殖户都遇到了类似情况。
演武村另一位养猪户称，他曾把一头母猪卖到屠宰场，屠宰场的人告诉他，这头猪的卵巢里都是水。
张超村村民左金玉也遇到这种情况，他说，有一人家里的猪死后，他想看看究竟是什么原因导致的，于是解剖，惊讶地看到猪的肚子里都是水。而左金玉在去年因为死猪问题也损失惨重，“有的小猪在母猪肚里就死了。还有60多头小猪长到了50多斤，莫名其妙地死了，赔了我6万多块钱。”左金玉养了13年的猪，猪出问题主要集中在这儿年。
地处吉林省榆树市西北部的弓棚镇，是全国闻名的生猪集散地。不过，当记者7月底到该镇调查时，发现这里很多村子的养猪业已经变得萧条。
13村养猪户康健民去年底放弃了养猪，他说:“一方面的冲击来自于市场，另一方面是各种病在这儿年突然大量出现。”
康健民介绍，这两年不仅有口蹄疫、心肌炎等疾病，还有很多未知的病。“这些病兽医根本无法诊断，他们只会让你试药，
这种不行换下一种，等我换儿次猪都死了。”
作为老养殖户，9村村民侯德军的直觉是这儿年猪的死亡率奇高，“无论是儿百斤的大猪，还是儿斤的小猪，不知得什么病就死了。”
先玉335涉嫌
除了老鼠和猪以外，记者还在晋中发现了羊和狗出现异常的情况。杨村的一位养羊专业户介绍，以前母羊一胎能生两到三只，但是现在只有一只，最多时两只。一名狗贩子也与记者聊起，现在狗经常出现肝腹水或者肾腹水的情况，剖开肚子总会有很多水。
到底是什么原因导致这些动物出现了让人不解的异常?
对于猪的异常，榆树兴源种猪繁育场场主赵万胜认为是因为吃了霉变的玉米。
不过，生猪养殖户们并不认同这些分析。他们告诉记者，用来喂猪的玉米没有发霉，而且不可能四五年都发霉。毕业于山西农业大学的阳谷县兽医贺裕向记者透露，向他求助的农民都反映了类似的情况:家里种了先玉335玉米。
而记者在采访中发现，这些出现异常的动物，也儿乎都吃过同一种玉米———先玉335。
在记者调查的所有养猪户中，他们均表示，自从家里种了先玉335玉米，这些玉米就成了猪饲料。而猪出现异常，也都是在以这些玉米为饲料之后。
晋中的羊虽然不是直接吃的先玉335，但是主要饲料是当地用玉米做完醋后的玉米渣，就是当地俗称的“醋糟”。
记者在弓棚镇新农村9村采访时，发现了一家母猪没有出现异常的养殖户。这个养殖户从去年开始养母猪，目前保持十儿头的规模，她称家里的母猪一般都有12头的产子率。记者特地问到了猪的饲料问题，这位养殖户介绍，她喂的是自家种的玉米，主要是国产的“信誉1”，她没有种过先玉335。
不过，记者采访的农民很少怀疑是他们给动物吃的饲料出了问题。甚至有人认为，吃玉米能吃出问题是“天方夜谭”，老鼠出问题，人也应该出问题。而有专家告诉记者，先玉335在2004年正式推
广，2006年开始普及。5-6年的时间，老鼠可以繁殖20代以上，猪可以传3代，而这个时长仅为人的生命周期的十分之一，因此，老鼠表现突出，人却不会出现严重的反应。
父本是转基因
在世界多个国家的转基因动物实验中，都发现了与晋中和榆树地区类似的动物异常现象。其中，美国国家科学院和美国卫生部等部门发表的文献说明了世界各地由于使用转基因饲料出现异常的案例，包括内脏发生异常的老鼠，假孕或不育的猪和非正常死亡的母牛。行业组织报告还说，英国市场出现转基因大豆食品后，居民的过敏症上升了50%。
那么，先玉335是转基因玉米吗?根据中国农业部门的公告，先玉335是美国先锋公司选育的杂交玉米，其母本为PH6WC，父本为PH4CV，均为先锋公司自育。
先锋良种国际有限公司在接受记者采访时称，先玉335“不含有转基因成分”。
查证的过程异常艰难。后来在一位海外读者的协助下，记者终于在美国专利商标局的官方网站上查到了关于PH4CV的信息。
长长的专利资料显示，PH4CV的开发包括了使用BT和HT转基因技术———这是用于商业化大宗农作物的仅有的两类转基因技术。
对转基因问题非常关心的云南财经大学社会与经济行为研究中心教授顾秀林认为，转过一次基因以后的作物不论经过多少代自交，然后再做多少次杂交，也不是传统意义上的杂交品种，而是转基因品种。
“如果是这样的话，山西、吉林等地的各种动物异常反应就有了比较合理的解释，因为世界各地独立试验均揭示转基因食品喂养动物会出现肾脏和肝脏损害、生殖系统出问题、免疫不正常，而这种大面积多地区类似的异常反应也绝非仅仅是环境因素改变而形成，这意味着转基因玉米正在我国进行着实实在在的非模拟检验。”一位业内人士说。
据《国际先驱导报》
附带转发"转基因玉米惹祸 "报道一篇，希望有些专业人士意见。
http://news.sina.com.cn/c/2010-09-22/100318149161s.shtml
转基因玉米惹祸
http://www.sina.com.cn 2010年09月22日10:03 大众网-齐鲁晚报
大老鼠消失、母猪爱生死胎、狗肚子里都是水，此外，羊也出现异常情况。全国闻名的生猪集散地，很多村子的养猪业已经变得萧条。而这些出现异常的动物，几乎都吃过同一种玉米———先玉335。美国的专利记录显示，中国大量种植的玉米种子“先玉335”的父本PH4CV的类别编号指示为转基因农作物。
一直深受鼠患之苦的山西晋中张庆乡农民刘旻(化名)，现在却为当地老鼠绝迹而感到不安。
刘旻家里种了十来亩玉米。“过去，家里的老鼠经常是蹿上蹿下的，需要买剧毒鼠药，从3年前开始，我突然发现即使不放老鼠药，也少有老鼠吃家里东西了。”刘旻说。
为此，刘旻开始观察了解村里的老鼠情况，情况大同小异:大老鼠基本绝迹，只有一些小老鼠，看上去也是呆头呆脑的。
今年5月，记者在晋中8个村庄走访，进一步印证了刘旻所说的动物异常情况。许多村民都证实“老鼠变少了”，尤其是不见大老鼠。
远在吉林省榆树市秀水镇苏家村的于彦辉有着同样的困惑。他发现最近三年以来，庄稼地里的老鼠突然没了，“以前那些老鼠专门啃玉米棒，要放很多老鼠药;现在村民打完的玉米堆放在地里，也没有老鼠跑来吃。”
对于老鼠为何减少，村民陈陶陪认为是因为三四年前榆树市里曾统一在地里放药，另外的原因则是老鼠的天敌比如黄鼠狼、老鹰多了。
不过，他还是有些困惑，以前也有老鼠的天敌，为何那时老鼠那么多。“也可能是生态环境改变的原因。”
但是，儿名村民均表示最近儿年村庄周围没有影响生态环境的因素，除了周边建了两个砖厂外，没有建其他企业，更没有什么废水污染物排出。
猪肚里都是水
从5月到8月，记者儿次在晋中和榆树附近的农村走访调查老鼠变少的情况，却发现了当地另外的怪事:母猪产子少了，不育、假育、流产的情况比较多。
养猪户张健红养猪快十年了，他说，以前他家养的20多头母猪，一窝猪最多能生16只，从来没有低过10只的。也就是在4年前，他发现母猪生的小猪越来越少。
“有时只有六七只，总之这儿年生的小猪没有上过10头的。”他
还反映说，自己家里同时养了儿十头肥猪，生长的速度明显比前儿年放慢。这儿年养猪一直亏本的他不得不先后卖掉了十儿只母猪。“我把剩下的儿只猪卖完就不再养了。”张健红说。
苏家村的养猪户陈红军也遇到了类似的情况。由于最近三年，猪死胎、流产的现象较多，让他至少损失了1/3的小猪。村里不少的个体养殖户都遇到了类似情况。
演武村另一位养猪户称，他曾把一头母猪卖到屠宰场，屠宰场的人告诉他，这头猪的卵巢里都是水。
张超村村民左金玉也遇到这种情况，他说，有一人家里的猪死后，他想看看究竟是什么原因导致的，于是解剖，惊讶地看到猪的肚子里都是水。而左金玉在去年因为死猪问题也损失惨重，“有的小猪在母猪肚里就死了。还有60多头小猪长到了50多斤，莫名其妙地死了，赔了我6万多块钱。”左金玉养了13年的猪，猪出问题主要集中在这儿年。
地处吉林省榆树市西北部的弓棚镇，是全国闻名的生猪集散地。不过，当记者7月底到该镇调查时，发现这里很多村子的养猪业已经变得萧条。
13村养猪户康健民去年底放弃了养猪，他说:“一方面的冲击来自于市场，另一方面是各种病在这儿年突然大量出现。”
康健民介绍，这两年不仅有口蹄疫、心肌炎等疾病，还有很多未知的病。“这些病兽医根本无法诊断，他们只会让你试药，
这种不行换下一种，等我换儿次猪都死了。”
作为老养殖户，9村村民侯德军的直觉是这儿年猪的死亡率奇高，“无论是儿百斤的大猪，还是儿斤的小猪，不知得什么病就死了。”
先玉335涉嫌
除了老鼠和猪以外，记者还在晋中发现了羊和狗出现异常的情况。杨村的一位养羊专业户介绍，以前母羊一胎能生两到三只，但是现在只有一只，最多时两只。一名狗贩子也与记者聊起，现在狗经常出现肝腹水或者肾腹水的情况，剖开肚子总会有很多水。
到底是什么原因导致这些动物出现了让人不解的异常?
对于猪的异常，榆树兴源种猪繁育场场主赵万胜认为是因为吃了霉变的玉米。
不过，生猪养殖户们并不认同这些分析。他们告诉记者，用来喂猪的玉米没有发霉，而且不可能四五年都发霉。毕业于山西农业大学的阳谷县兽医贺裕向记者透露，向他求助的农民都反映了类似的情况:家里种了先玉335玉米。
而记者在采访中发现，这些出现异常的动物，也儿乎都吃过同一种玉米———先玉335。
在记者调查的所有养猪户中，他们均表示，自从家里种了先玉335玉米，这些玉米就成了猪饲料。而猪出现异常，也都是在以这些玉米为饲料之后。
晋中的羊虽然不是直接吃的先玉335，但是主要饲料是当地用玉米做完醋后的玉米渣，就是当地俗称的“醋糟”。
记者在弓棚镇新农村9村采访时，发现了一家母猪没有出现异常的养殖户。这个养殖户从去年开始养母猪，目前保持十儿头的规模，她称家里的母猪一般都有12头的产子率。记者特地问到了猪的饲料问题，这位养殖户介绍，她喂的是自家种的玉米，主要是国产的“信誉1”，她没有种过先玉335。
不过，记者采访的农民很少怀疑是他们给动物吃的饲料出了问题。甚至有人认为，吃玉米能吃出问题是“天方夜谭”，老鼠出问题，人也应该出问题。而有专家告诉记者，先玉335在2004年正式推
广，2006年开始普及。5-6年的时间，老鼠可以繁殖20代以上，猪可以传3代，而这个时长仅为人的生命周期的十分之一，因此，老鼠表现突出，人却不会出现严重的反应。
父本是转基因
在世界多个国家的转基因动物实验中，都发现了与晋中和榆树地区类似的动物异常现象。其中，美国国家科学院和美国卫生部等部门发表的文献说明了世界各地由于使用转基因饲料出现异常的案例，包括内脏发生异常的老鼠，假孕或不育的猪和非正常死亡的母牛。行业组织报告还说，英国市场出现转基因大豆食品后，居民的过敏症上升了50%。
那么，先玉335是转基因玉米吗?根据中国农业部门的公告，先玉335是美国先锋公司选育的杂交玉米，其母本为PH6WC，父本为PH4CV，均为先锋公司自育。
先锋良种国际有限公司在接受记者采访时称，先玉335“不含有转基因成分”。
查证的过程异常艰难。后来在一位海外读者的协助下，记者终于在美国专利商标局的官方网站上查到了关于PH4CV的信息。
长长的专利资料显示，PH4CV的开发包括了使用BT和HT转基因技术———这是用于商业化大宗农作物的仅有的两类转基因技术。
对转基因问题非常关心的云南财经大学社会与经济行为研究中心教授顾秀林认为，转过一次基因以后的作物不论经过多少代自交，然后再做多少次杂交，也不是传统意义上的杂交品种，而是转基因品种。
“如果是这样的话，山西、吉林等地的各种动物异常反应就有了比较合理的解释，因为世界各地独立试验均揭示转基因食品喂养动物会出现肾脏和肝脏损害、生殖系统出问题、免疫不正常，而这种大面积多地区类似的异常反应也绝非仅仅是环境因素改变而形成，这意味着转基因玉米正在我国进行着实实在在的非模拟检验。”一位业内人士说。
据《国际先驱导报》
专家不是都有定论了嘛，跟转基因没关系。
最近微博转发地很火的一条就是：“。。。。有毒小龙虾跟洗虾粉没关系、不良反应跟疫苗没关系、专家老婆怀孕了——跟专家没关系。”
最近微博转发地很火的一条就是：“。。。。有毒小龙虾跟洗虾粉没关系、不良反应跟疫苗没关系、专家老婆怀孕了——跟专家没关系。”
有毒小龙虾跟洗虾粉没关系、不良反应跟疫苗没关系、专家老婆怀孕了——跟专家没关系。”
转基因食品是否含有转座变异呢，如果转座变异对哺乳动物影响是否有什么特殊含义
转基因还是谨慎点，不要信专家的，专家自己也没有每餐吃。没一个人敢保证转基因的安全。
专家支持进口的
山西澄清：动物异常与玉米无关
http://news.163.com/10/0923/06/6H8E2PCU00014AED.html
http://news.163.com/10/0923/06/6H8E2PCU00014AED.html
有毒小龙虾跟洗虾粉没关系、不良反应跟疫苗没关系、专家老婆怀孕了——跟专家没关系。”
悲哀 中国的专家呀……
这时候方舟子怎么连P也不放了
偶尔看到“天涯论坛-天涯杂谈”--中 署名方舟子的报导“《国际先驱导报》又造谣抹黑转基因”，各种声音正好可以“百家争鸣”一下，特转贴如下：
http://www.tianya.cn/publicforum/content/free/1/1986818.shtml
http://www.tianya.cn/publicforum/content/free/1/1986818.shtml
正腐说了“先玉335”不是转基因农作物！
先玉335据说不是转基因植物。。。
这有关于死老鼠新闻的确实报道。http://news.163.com/10/0923/06/6H8E2PCU00014AED.html
我比较关心的是要是真的是转基因玉米惹祸的话，那究竟是它的蛋白发生作用呢，还是载体发生转移，或者是别的作用机理。
呵呵，看着吧，生化危机的前传在现实生活中逐渐上演！
同意楼上，如果是转基因惹的祸，基因专家解释下其机理，我是临床，这个细节搞不懂
知道的可以不吃，很多时候吃了也不知道。
不可能是转基因，因为要出事，也不会这么快，起码是几十年之后的事情了。
目前的研究还没有找到转基因对人体存在直接的危害。
目前的研究还没有找到转基因对人体存在直接的危害。
粮食安全不同与其他领域。首先是粮食安全涉及的范围最广，影响和危害也是其他领域无法相比的；其次是粮食安全问题具有隐蔽性，普通商品觉得有问题可以不用，药品感觉不安全可以不吃，但是食品不同。相信没有人可以说出自己吃的大米是什么品种的！现在没有足够权威的证据说明转基因食品是有害的，但是同样的也没有充足的事实说明转基因食品无害。一些药品的不良反应都需要几十年才能逐渐被发现，更何况是食品呢。世界各国对生物药品的监管非常严格，而对同样是生物技术得到的食品却采取如此宽松的态度令人担忧！一个上市3年的药品敢说自己绝对不存在安全隐患吗？何况上市3年的食品啊！
关心起这个来了。中国现在的食品问题还轮不到考虑转基因的安全问题，看看饭店的油，吃的大米，菜里面的农药，这些才是你每天都在接触的东西
同问，貌似现在很多反对转基因的言论，论据只停留在宏观上跟经济上，而对转基因到底有什么危害是什么机理，语焉不详。
张明建 wrote:
这时候方舟子怎么连P也不放了
以下是方舟子的微博： 美国种植的玉米80％以上都是转基因品种，如果转基因玉米能让老鼠死亡，美国
的老鼠早就死光了。《国际先驱导报》这么弱智的谣言居然还有那么多人信，何
况他们说的那个玉米品种“先玉335”根本不是转基因品种，而是杂交品种。中
国还没批准转基因玉米的种植，美国已种了、吃了14年。
9月19日 00:03
美国玉米还有一部分是直接煮着吃的（所谓甜玉米），一部分是粗加工成玉米粉，
做成玉米饼等各种墨西哥食品或快餐。 //@汉子宙:玉米一部分深加工成其他食
物 美国超市超过六成食品含玉米深加工品 另外玉米也主要用于畜牧饲料 生物
质能
9月19日 15:41
《国际先驱导报》造谣说先玉335是转基因玉米，因为他们查过其父本PH4CV的专
利说明说是转基因玉米。PH4CV的专利（专利号6897363）说得清清楚楚，近交系
玉米（An inbred maize line），连杂交都不是，是最“天然”的。只不过在权
利声明（claims）里头表明了保留以后作为转基因玉米材料的权利，于是就被
《国际先驱导报》歪曲成是转基因的了。
9月19日 15:47
英文不好。把专利说明帖上，大家看一下：
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6897363.PN.&OS=PN/6897363&RS=PN/6897363
United States Patent 6,897,363
Barker May 24, 2005
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Inbred maize line PH4CV
Abstract
An inbred maize line, designated PH4CV, the plants and seeds of inbred maize line PH4CV, methods for producing a maize plant, either inbred or hybrid, produced by crossing the inbred maize line PH4CV with another maize plant, and hybrid maize seeds and plants produced by crossing the inbred line PH4CV with another maize line or plant and to methods for producing a maize plant containing in its genetic material one or more transgenes and to the transgenic maize plants produced by that method. This invention also relates to inbred maize lines derived from inbred maize line PH4CV, to methods for producing other inbred maize lines derived from inbred maize line PH4CV and to the inbred maize lines derived by the use of those methods.
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Inventors: Barker; Thomas Charles (York, NE)
Assignee: Pioneer Hi-Bred International, Inc. (Johnston, IA)
Appl. No.: 10/271,942
Filed: October 15, 2002
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Current U.S. Class: 800/320.1 ; 435/412; 800/275; 800/278; 800/279; 800/281; 800/298; 800/300.1; 800/301; 800/302; 800/303
Current International Class: A01H 5/10 (20060101); A01H 001/00 (); A01H 004/00 (); A01H 005/00 (); A01H 005/10 (); C12N 015/82 ()
Field of Search: 800/320.1,266,275,278,279,284,298,300.1,301,302,303 435/412
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References Cited [Referenced By]
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U.S. Patent Documents
5436390 July 1995 Oestreich
5563325 October 1996 Morrow
5792911 August 1998 Anderson
5850010 December 1998 Anderson
6333453 December 2001 Henke
Other References
Plant Variety Protection Certificate No. 9500200 for Corn PHBE2, issued Aug. 13, 1996. .
Plant Variety Protection Certificate No. 9100097 for Corn PHRO3, issued Apr. 30, 1992. .
Plant Variety Protection Certificate No. 200000242 for Corn, Field PH1BC, issued Jan. 13, 2002. .
Plant Variety Protection Certificate No. 200000243 for Corn, Field PH2EJ, issued Feb., 5, 2002. .
Plant Variety Protection Certificate No. 9600200 for Corn PH56C, issued Jul. 30, 1999. .
Plant Variety Protection Certificate No. 9700223 for Corn, Field, PH24M, issued Apr., 24, 2001..
Primary Examiner: Kruse; David H
Attorney, Agent or Firm: McKee, Voorhees & Sease, P.L.C.
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Parent Case Text
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit of the priority date of U.S. Patent Application Ser. No. 60/352,317 filed Jan. 28, 2002, which is hereby incorporated herein by reference.
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Claims
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What is claimed is:
1. A seed of maize inbred line designated PH4CV, representative seed of said line having been deposited under ATCC Accession No. PTA-4673.
2. A maize plant, or a part thereof, produced by growing the seed of claim 1.
3. The maize plant of claim 2, wherein said plant has been detasseled.
4. A tissue culture of regenerable cells produced from the plant of claim 2.
5. A protoplast produced from the tissue culture of claim 4.
6. The tissue culture of claim 4, wherein cells of the tissue culture are produced from a tissue selected from the group consisting of leaf, pollen, embryo, root, root tip, anther, silk, flower, kernel, ear, cob, husk and stalk.
7. A maize plant regenerated from the tissue culture of claim 4, said plant having all the morphological and physiological characteristics of inbred line PH4CV, representative seed of said inbred line having been deposited under ATCC Accession No. PTA-4673.
8. A method for producing an F1 hybrid maize seed, comprising crossing the plant of claim 2 with a different maize plant and harvesting the resultant F1 hybrid maze seed.
9. A method of producing a male sterile maize plant comprising transforming the maize plant of claim 2 with a nucleic acid molecule that confers male sterility.
10. A male sterile maize plant produced by the method of claim 9.
11. A method of producing an herbicide resistant maize plant comprising transforming the maize plant of claim 2 with a transgene that confers herbicide resistance.
12. An herbicide resistant maize plant produced by the method of claim 11.
13. The maize plant of claim 12, wherein the transgene confers resistance to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, glufosinate, L-phosphinothricin, triazine and benzonitrile.
14. A method of producing an insect resistant maize plant comprising transforming the maize plant of claim 2 with a transgene that confers insect resistance.
15. An insect resistant maize plant produced by the method of claim 14.
16. The maize plant of claim 15, wherein the transgene encodes a Bacillus thuringiensis endotoxin.
17. A method of producing a disease resistant maize plant comprising transforming the maize plant of claim 2 with a transgene that confers disease resistance.
18. A disease resistant maize plant produced by the method of claim 17.
19. A method of producing a maize plant with decreased phytate content comprising transforming the maize plant of claim 2 with a transgene encoding phytase.
20. A maize plant with decreased phytate content produced by the method of claim 19.
21. A method of producing a maize plant with modified fatty acid metabolism or modified carbohydrate metabolism comprising transforming the maize plant of claim 2 with a transgene encoding a protein selected from the group consisting of fructosyltransferase, levansucrase, alpha-amylase, invertase and starch branching enzyme or encoding an antisense of stearyl-ACP desaturase.
22. A maize plant, with modified fatty acid metabolism or modified carbohydrate metabolism, produced by the method of claim 21.
23. The maize plant of 22 wherein the transgene confers a trait selected from the group consisting of waxy starch and increased amylose starch.
24. A maize plant, or part thereof, having all the physiological and morphological characteristics of the inbred line PH4CV, representative seed of said inbred line having been deposited under ATCC Accession No. PTA-4673.
25. A method of introducing a desired trait into maize inbred line PH4CV comprising: (a) crossing PH4CV plants grown from PH4CV seed, representative seed of which has been deposited under ATCC Accession No. PTA-4673, with plants of another maize line that comprise a desired trait to produce F1 progeny plants, wherein the desired trait is selected from the group consisting of male sterility, herbicide resistance, insect resistance, disease resistance and waxy starch; (b) selecting F1 progeny plants that have the desired trait to produce selected F1 progeny plants; (c) crossing the selected progeny plants with the PH4CV plants to produce backcross progeny plants; (d) selecting for backcross progeny plants that have the desired trait and physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 to produce selected backcross progeny plants; and (e) repeating steps (c) and (d) three or more times in succession to produce selected fourth or higher backcross progeny plants that comprise the desired trait and all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
26. A plant produced by the method of claim 25, wherein the plant has the desired trait and all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
27. The plant of claim 26 wherein the desired trait is herbicide resistance and the resistance is conferred to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, glufosinate, L-phosphinothricin, triazine and benzonitrile.
28. The plant of claim 26 wherein the desired trait is insect resistance and the insect resistance is conferred by a transgene encoding a Bacillus thuringiensis endotoxin.
29. The plant of claim 26 wherein the desired trait is male sterility and the trait is conferred by a cytoplasmic nucleic acid molecule that confers male sterility.
30. A method of modifying fatty acid metabolism, phytic acid metabolism or carbohydrate in maize inbred line PH4CV comprising: (a) crossing PH4CV plants grown from PH4CV seed, representative seed of which has been deposited under ATCC Accession No. PTA-4673, with plants of another maize line that comprise a nucleic acid molecule encoding an enzyme selected from the group consisting of phytase, fructosyltransferase, levansucrase, alpha-amylase, invertase and starch branching enzyme or encoding an antisense of stearyl-ACP desaturase; (b) selecting F1 progeny plants that have said nucleic acid molecule to produce selected F1 progeny plants; (c) crossing the selected progeny plants with the PH4CV plants to produce backcross progeny plants; (d) selecting for backcross progeny plants that have said nucleic acid molecule and physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 to produce selected backcross progeny plants; and (e) repeating steps (c) and (d) three or more times in succession to produce selected fourth or higher backcross progeny plants that comprise said nucleic acid molecule and have all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
31. A plant, with modified fatty acid metabolism, modified phytic acid metabolism, or modified carbohydrate metabolism, produced by the method of claim 30, wherein the plant comprises the nucleic acid molecule and has all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
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Description
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FIELD OF THE INVENTION
This invention is in the field of maize breeding, specifically relating to an inbred maize line designated PH4CV.
BACKGROUND OF THE INVENTION
The goal of plant breeding is to combine in a single variety or hybrid, various desirable traits. For field crops, these traits may include resistance to diseases and insects, tolerance to heat and drought, reducing the time to crop maturity, greater yield, and better agronomic quality. With mechanical harvesting of many crops, uniformity of plant characteristics such as germination and stand establishment, growth rate, maturity, and plant and ear height, is important.
Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is sib-pollinated when individuals within the same family or line are used for pollination. A plant is cross-pollinated if the pollen comes from a flower on a different plant from a different family or line. The terms "cross-pollination" and "out-cross" as used herein do not include self-pollination or sib-pollination.
Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two different homozygous lines produces a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two plants, each heterozygous at a number of gene loci will produce a population of hybrid plants that differ genetically and will not be uniform.
Maize (zea mays L.), often referred to as corn in the United States, can be bred by both self-pollination and cross-pollination techniques. Maize has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in maize when wind blows pollen from the tassels to the silks that protrude from the tops of the ears.
A reliable method of controlling male fertility in plants offers the opportunity for improved plant breeding. This is especially true for development of maize hybrids, which relies upon some sort of male sterility system. There are several ways in which a maize plant can be manipulated so that it is male sterile. These include use of manual or mechanical emasculation (or detasseling), use of cytoplasmic genetic or nuclear genetic male sterility, use of gametocides and is the like.
Hybrid maize seed is typically produced by a male sterility system incorporating manual or mechanical detasseling. Alternate strips of two maize inbreds are planted in a field, and the pollen-bearing tassels are removed from one of the inbreds (female). Provided that there is sufficient isolation from sources of foreign maize pollen, the ears of the detasseled inbred will be fertilized only from the other inbred (male), and the resulting seed is therefore hybrid and will form hybrid plants.
The laborious detasseling process can be avoided by using cytoplasmic male-sterile (CMS) inbreds. Plants of a CMS inbred are male sterile as a result of factors resulting from the cytoplasmic, as opposed to the nuclear, genome. Thus, this characteristic is inherited exclusively through the female parent in maize plants, since only the female provides cytoplasm to the fertilized seed. CMS plants are fertilized with pollen from another inbred that is not male-sterile. Pollen from the second inbred may or may not contribute genes that make the hybrid plants male-fertile. The same hybrid seed, a portion produced from detasseled fertile maize and a portion produced using the CMS system, can be blended to insure that adequate pollen loads are available for fertilization when the hybrid plants are grown.
There are several methods of conferring genetic male sterility available, such as multiple mutant genes at separate locations within the genome that confer male sterility, as disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar et al. and chromosomal translocations as described by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. These and all patents, patent applications and publications referred to herein are incorporated by reference. In addition to these methods, Albertsen et al., of Pioneer Hi-Bred, U.S. Pat. No. 5,432,068, have developed a system of nuclear male sterility which includes: identifying a gene which is critical to male fertility; silencing this native gene which is critical to male fertility; removing the native promoter from the essential male fertility gene and replacing it with an inducible promoter; inserting this genetically engineered gene back into the plant; and thus creating a plant that is male sterile because the inducible promoter is not "on" resulting in the male fertility gene not being transcribed. Fertility is restored by inducing, or turning "on", the promoter, which in turn allows the gene that confers male fertility to be transcribed.
These, and the other methods of conferring genetic male sterility in the art, each possess their own benefits and drawbacks. Some other methods use a variety of approaches such as delivering into the plant a gene encoding a cytotoxic substance associated with a male tissue specific promoter or an antisense system in which a gene critical to fertility is identified and an antisense to that gene is inserted in the plant (see: Fabinjanski, et al. EPO 89/3010153.8 publication no. 329,308 and PCT application PCT/CA90/00037 published as WO 90/08828).
Another system for controlling male sterility makes use of gametocides. Gametocides are not a genetic system, but rather a topical application of chemicals. These chemicals affect cells that are critical to male fertility. The application of these chemicals affects fertility in the plants only for the growing season in which the gametocide is applied (see Carlson, Glenn R., U.S. Pat. No. 4,936,904). Application of the gametocide, timing of the application and genotype specificity often limit the usefulness of the approach and it is not appropriate in all situations.
Development of Maize Inbred Lines
The use of male sterile inbreds is but one factor in the production of maize hybrids. Plant breeding techniques known in the art and used in a maize plant breeding program include, but are not limited to, recurrent selection, backcrossing, pedigree breeding, restriction fragment length polymorphism enhanced selection, genetic marker enhanced selection, making double haploids, and transformation. Often a combination of these techniques is used. The development of maize hybrids in a maize plant breeding program requires, in general, the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses.
Maize plant breeding programs combine the genetic backgrounds from two or more inbred lines or various other germplasm sources into breeding populations from which new inbred lines are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred lines and the hybrids from these crosses are evaluated to determine which of those have commercial potential. Plant breeding and hybrid development, as practiced in a maize plant breeding program developing significant genetic advancement, are expensive and time-consuming processes.
Pedigree breeding starts with the crossing of two genotypes, such as two elite inbred lines, each of which may have one or more desirable characteristics that is lacking in the other or which complements the other. If the two original parents do not provide all the desired characteristics, other sources can be included in the breeding population. In the pedigree method, superior plants are selfed and selected in successive filial generations. In the succeeding filial generations the heterozygous condition gives way to homogeneous lines as a result of self-pollination and selection. Typically in the pedigree method of breeding, five or more successive filial generations of selfing and selection is practiced: F.sub.1.fwdarw.F.sub.2 ; F.sub.2.fwdarw.F.sub.3 ; F.sub.3.fwdarw.F.sub.4 ; F.sub.4.fwdarw.F.sub.5, etc. After a sufficient amount of inbreeding, successive filial generations will serve to increase seed of the developed inbred. Preferably, an inbred line comprises homozygous alleles at about 95% or more of its loci.
Backcrossing can be used to improve an inbred line and a hybrid that is made using those inbreds. Backcrossing can be used to transfer a specific desirable trait from one line, the donor parent, to an inbred called the recurrent parent which has overall good agronomic characteristics yet lacks that desirable trait. This transfer of the desirable trait into an inbred with overall good agronomic characteristics can be accomplished by first crossing a recurrent parent and a donor parent (non-recurrent parent). The progeny of this cross is then mated back to the recurrent parent followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent as well as selection for the characteristics of the recurrent parent. Typically after four or more backcross generations with selection for the desired trait and the characteristics of the recurrent parent, the progeny will contain essentially all genes of the recurrent parent except for the genes controlling the desired trait. However, the number of backcross generations can be less if molecular markers are used during selection or elite germplasm is used as the donor parent. The last backcross generation is then selfed to give pure breeding progeny for the gene(s) being transferred. Backcrossing can also be used in conjunction with pedigree breeding to develop new inbred lines. For example, an F1 can be created that is backcrossed to one of its parent lines to create a BC1, BC2, BC3, etc. Progeny are selfed and selected so that the newly developed inbred has many of the attributes of the recurrent parent and some of the desired attributes of the non-recurrent parent. This approach leverages the value and strengths of the recurrent parent for use in new hybrids and breeding which has very significant value for a breeder.
Recurrent selection is a method used in a plant breeding program to improve a population of plants. The method entails individual plants cross-pollinating with each other to form progeny, which are then grown. The superior progeny are then selected by any number of methods, which include individual plant, half-sib progeny, full-sib progeny, selfed progeny and topcrossing. The selected progeny are cross-pollinated with each other to form progeny for another population. This population is planted and again superior plants are selected to cross-pollinate with each other. Recurrent selection is a cyclical process and therefore can be repeated as many times as desired. The objective of recurrent selection is to improve the traits of a population. The improved population can then be used as a source of breeding material to obtain inbred lines to be used in hybrids or used as parents for a synthetic cultivar. A synthetic cultivar is the resultant progeny formed by the intercrossing of several selected inbreds. Mass selection is a useful technique when used in conjunction with molecular marker enhanced selection.
Mutation breeding is one of the many methods of introducing new traits into inbred lines. Mutations that occur spontaneously or are artificially induced can be useful sources of variability for a plant breeder. The goal of artificial mutagenesis is to increase the rate of mutation for a desired characteristic. Mutation rates can be increased by many different means including temperature, long-term seed storage, tissue culture conditions, radiation; such as X-rays, Gamma rays (e.g. cobalt 60 or cesium 137), neutrons, (produce of nuclear fission by uranium 235 on an atomic reactor), Beta radiation (emitted from radioisotopes such as phosphorus 32 or carbon 14), or ultraviolet radiation (preferably from 2500 to 2900 nm), or chemical mutagens (such as base analogues (5-bromo-uracil), related compounds (8-ethoxy caffeine), antibiotics (streptonigrin), alkylating agents (sulfur mustards, nitrogen mustards, epoxides, ethylenamines, sulfates, sulfonates, sulfones, lactones), azide, hydroxylamine, nitrous acid, or acridines. Once a desired trait is observed through mutagenesis the trait may then be incorporated into existing germplasm by traditional breeding techniques. Details of mutation breeding can be found in "Principals of Cultivar Development" Fehr, 1993 Macmillan Publishing Company the disclosure of which is incorporated herein by reference.
Molecular markers, which includes markers identified through the use of techniques such as Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs) and Single Nucleotide Polymorphisms (SNPs), may be used in plant breeding methods. One use of molecular markers is Quantitative Trait Loci (QTL) mapping. QTL mapping is the use of markers, which are known to be closely linked to alleles that have measurable effects on a quantitative trait. Selection in the breeding process is based upon the accumulation of markers linked to the positive effecting alleles and/or the elimination of the markers linked to the negative effecting alleles from the plant's genome.
Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers closely linked to alleles or markers containing sequences within the actual alleles of interest can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select for the genome of the recurrent parent and against the genome of the donor parent. Using this procedure can minimize the amount of genome from the donor parent that remains in the selected plants. It can also be used to reduce the number of crosses back to the recurrent parent needed in a backcrossing program. The use of molecular markers in the selection process is often called genetic marker enhanced selection.
The production of double haploids can also be used for the development of inbreds in the breeding program. Double haploids are produced by the doubling of a set of chromosomes (1N) from a heterozygous plant to produce a completely homozygous individual. For example, see Wan et al., "Efficient Production of Doubled Haploid Plants Through Colchicine Treatment of Anther-Derived Maize Callus", Theoretical and Applied Genetics, 77:889-892, 1989. This can be advantageous because the process omits the generations of selfing needed to obtain a homozygous plant from a heterozygous source.
Development of Maize Hybrids
A single cross maize hybrid results from the cross of two inbred lines, each of which has a genotype that complements the genotype of the other. The hybrid progeny of the first generation is designated F.sub.1. In the development of commercial hybrids in a maize plant breeding program, only the F.sub.1 hybrid plants are sought. F.sub.1 hybrids are more vigorous than their inbred parents. This hybrid vigor, or heterosis, can be manifested in many polygenic traits, including increased vegetative growth and increased yield.
The development of a maize hybrid in a maize plant breeding program involves three steps: (1) the selection of plants from various germplasm pools for initial breeding crosses; (2) the selfing of the selected plants from the breeding crosses for several generations to produce a series of inbred lines, which, although different from each other, breed true and are highly uniform; and (3) crossing the selected inbred lines with different inbred lines to produce the hybrids. During the inbreeding process in maize, the vigor of the lines decreases. Vigor is restored when two different inbred lines are crossed to produce the hybrid. An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between a defined pair of inbreds will always be the same. Once the inbreds that give a superior hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained.
A single cross hybrid is produced when two inbred lines are crossed to produce the F.sub.1 progeny. A double cross hybrid is produced from four inbred lines crossed in pairs (A.times.B and C.times.D) and then the two F.sub.1 hybrids are crossed again (A.times.B).times.(C.times.D). A three-way cross hybrid is produced from three inbred lines where two of the inbred lines are crossed (A.times.B) and then the resulting F.sub.1 hybrid is crossed with the third inbred (A.times.B).times.C. Much of the hybrid vigor and uniformity exhibited by F.sub.1 hybrids is lost in the next generation (F.sub.2). Consequently, seed produced from hybrids is not used for planting stock.
Hybrid seed production requires elimination or inactivation of pollen produced by the female parent. Incomplete removal or inactivation of the pollen provides the potential for self-pollination. This inadvertently self-pollinated seed may be unintentionally harvested and packaged with hybrid seed. Also, because the male parent is grown next to the female parent in the field there is the very low probability that the male selfed seed could be unintentionally harvested and packaged with the hybrid seed. Once the seed from the hybrid bag is planted, it is possible to identify and select these self-pollinated plants. These self-pollinated plants will be genetically equivalent to one of the inbred lines used to produce the hybrid. Though the possibility of inbreds being included hybrid seed bags exists, the occurrence is very low because much care is taken to avoid such inclusions. It is worth noting that hybrid seed is sold to growers for the production of grain or forage and not for breeding or seed production.
These self-pollinated plants can be identified and selected by one skilled in the art due to their decreased vigor when compared to the hybrid. Inbreds are identified by their less vigorous appearance for vegetative and/or reproductive characteristics, including shorter plant height, small ear size, ear and kernel shape, cob color, or other characteristics.
Identification of these self-pollinated lines can also be accomplished through molecular marker analyses. See, "The Identification of Female Selfs in Hybrid Maize: A Comparison Using Electrophoresis and Morphology", Smith, J. S. C. and Wych, R. D., Seed Science and Technology 14, pp. 1-8 (1995), the disclosure of which is expressly incorporated herein by reference. Through these technologies, the homozygosity of the self-pollinated line can be verified by analyzing allelic composition at various loci along the genome. Those methods allow for rapid identification of the invention disclosed herein. See also, "Identification of Atypical Plants in Hybrid Maize Seed by Postcontrol and Electrophoresis" Sarca, V. et al., Probleme de Genetica Teoritica si Aplicata Vol. 20 (1) p. 29-42.
As is readily apparent to one skilled in the art, the foregoing are only some of the various ways by which the inbred can be obtained by those looking to use the germplasm. Other means are available, and the above examples are illustrative only.
Maize is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop high-yielding maize hybrids that are agronomically sound based on stable inbred lines. The reasons for this goal are obvious: to maximize the amount of grain produced with the inputs used and minimize susceptibility of the crop to pests and environmental stresses. To accomplish this goal, the maize breeder must select and develop superior inbred parental lines for producing hybrids. This requires identification and selection of genetically unique individuals that occur in a segregating population. The segregating population is the result of a combination of crossover events plus the independent assortment of specific combinations of alleles at many gene loci that results in specific genotypes. The probability of selecting any one individual with a specific genotype from a breeding cross is infinitesimal due to the large number of segregating genes and the unlimited recombinations of these genes, some of which may be closely linked. However, the genetic variation among individual progeny of a breeding cross allows for the identification of rare and valuable new genotypes. These new genotypes are neither predictable nor incremental in value, but rather the result of manifested genetic variation combined with selection methods, environments and the actions of the breeder. Once identified, it is possible to utilize routine and predictable breeding methods to develop progeny that retain the rare and valuable new genotypes developed by the initial breeder.
Even if the entire genotypes of the parents of the breeding cross were characterized and a desired genotype known, only a few if any individuals having the desired genotype may be found in a large segregating F.sub.2 population. It would be very unlikely that a breeder of ordinary skill in the art would able to recreate the same line twice from the very same original parents, as the breeder is unable to direct how the genomes combine or how they will interact with the environmental conditions. This unpredictability results in the expenditure of large amounts of research resources in the development of a superior new maize inbred line. Once such a line is developed its value to society is substantial since it is important to advance the germplasm base as a whole in order to maintain or improve traits such as yield, disease resistance, pest resistance and plant performance in extreme conditions.
A breeder uses various methods to help determine which plants should be selected from the segregating populations and ultimately which inbred lines will be used to develop hybrids for commercialization. In addition to the knowledge of the germplasm and other skills the breeder uses, a part of the selection process is dependent on experimental design coupled with the use of statistical analysis. Experimental design and statistical analysis are used to help determine which plants, which family of plants, and finally which inbred lines and hybrid combinations are significantly better or different for one or more traits of interest. Experimental design methods are used to assess error so that differences between two inbred lines or two hybrid lines can be more accurately determined. Statistical analysis includes the calculation of mean values, determination of the statistical significance of the sources of variation, and the calculation of the appropriate variance components. Either a five or a one percent significance level is customarily used to determine whether a difference that occurs for a given trait is real or due to the environment or experimental error.
One of ordinary skill in the art of plant breeding would know how to evaluate the traits of two plant varieties to determine if there is no significant difference between the two traits expressed by those varieties. For example, see Fehr, Walt, Principles of Cultivar Development, p. 261-286 (1987) which is incorporated herein by reference. Mean trait values may be used to determine whether trait differences are significant, and preferably the traits are measured on plants grown under the same environmental conditions.
Combining ability of a line, as well as the performance of the line per se, is a factor in the selection of improved maize inbreds. Combining ability refers to a line's contribution as a parent when crossed with other lines to form hybrids. The hybrids formed for the purpose of selecting superior lines are designated testcrosses. One way of measuring combining ability is by using breeding values. Breeding values are based in part on the overall mean of a number of testcrosses. This mean is then adjusted to remove environmental effects and it is adjusted for known genetic relationships among the lines.
SUMMARY OF THE INVENTION
According to the invention, there is provided a novel inbred maize line, designated PH4CV. This invention thus relates to the seeds of inbred maize line PH4CV, to the plants of inbred maize line PH4CV, to plant parts of inbred maize line PH4CV, to methods for producing a maize plant produced by crossing the inbred maize line PH4CV with another maize plant, including a plant that is part of a synthetic or natural population, and to methods for producing a maize plant containing in its genetic material one or more transgenes and to the transgenic maize plants and plant parts produced by that method. This invention also relates to inbred maize lines and plant parts derived from inbred maize line PH4CV, to methods for producing other inbred maize lines derived from inbred maize line PH4CV and to the inbred maize lines and their parts derived by the use of those methods. This invention further relates to hybrid maize seeds, plants, and plant parts produced by crossing the inbred line PH4CV with another maize line.
Definitions
Certain definitions used in the specification are provided below. Also in the examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided. NOTE: ABS is in absolute terms and % MN is percent of the mean for the experiments in which the inbred or hybrid was grown. PCT designates that the trait is calculated as a percentage. % NOT designates the percentage of plants that did not exhibit a trait. For example, STKLDG % NOT is the percentage of plants in a plot that were not stalk lodged. These designators will follow the descriptors to denote how the values are to be interpreted.
ABTSTK=ARTIFICIAL BRITTLE STALK. A count of the number of "snapped" plants per plot following machine snapping. A snapped plant has its stalk completely snapped at a node between the base of the plant and the node above the ear. Expressed as percent of plants that did not snap.
ALLELE. Any of one or more alternative forms of a genetic sequence. In a diploid cell or organism, the two alleles of a given sequence occupy corresponding loci on a pair of homologous chromosomes.
ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola). A 1 to 9 visual rating indicating the resistance to Anthracnose Stalk Rot. A higher score indicates a higher resistance.
BACKCROSSING. Process in which a breeder crosses a progeny line back to one of the parental genotypes one or more times.
BARPLT=BARREN PLANTS. The percent of plants per plot that was not barren (lack ears).
BREEDING. The genetic manipulation of living organisms.
BRTSTK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap.
CLDTST=COLD TEST. The percent of plants that germinate under cold test conditions.
CLN=CORN LETHAL NECROSIS. Synergistic interaction of maize chlorotic mottle virus (MCMV) in combination with either maize dwarf mosaic virus (MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV). A 1 to 9 visual rating indicating the resistance to Corn Lethal Necrosis. A higher score indicates a higher resistance.
COMRST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicating the resistance to Common Rust. A higher score indicates a higher resistance.
D/D=DRYDOWN. This represents the relative rate at which a hybrid will reach acceptable harvest moisture compared to other hybrids on a 1-9 rating scale. A high score indicates a hybrid that dries relatively fast while a low score indicates a hybrid that dries slowly.
DIPERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodia macrospora). A 1 to 9 visual rating indicating the resistance to Diplodia Ear Mold. A higher score indicates a higher resistance.
DIPROT=DIPLODIA STALK ROT SCORE. Score of stalk rot severity due to Diplodia (Diplodia maydis). Expressed as a 1 to 9 score with 9 being highly resistant.
DRPEAR=DROPPED EARS. A measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.
D/T=DROUGHT TOLERANCE. This represents a 1-9 rating for drought tolerance, and is based on data obtained under stress conditions. A high score indicates good drought tolerance and a low score indicates poor drought tolerance.
EARHT=EAR HEIGHT. The ear height is a measure from the ground to the highest placed developed ear node attachment and is measured in centimeters.
EARMLD=General Ear Mold. Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining the specific mold organism, and may not be predictive for a specific ear mold.
EARSZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.
EBTSTK=EARLY BRITTLE STALK. A count of the number of "snapped" plants per plot following severe winds when the corn plant is experiencing very rapid vegetative growth in the V5-V8 stage. Expressed as percent of plants that did not snap.
ECB1LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinia nubilalis). A 1 to 9 visual rating indicating the resistance to preflowering leaf feeding by first generation European Corn Borer. A higher score indicates a higher resistance.
ECB2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING (Ostrinia nubilalis). Average inches of tunneling per plant in the stalk.
ECB2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1 to 9 visual rating indicating post flowering degree of stalk breakage and other evidence of feeding by European Corn Borer, Second Generation. A higher score indicates a higher resistance.
ECBDPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Dropped ears due to European Corn Borer. Percentage of plants that did not drop ears under second generation corn borer infestation.
EGRWTH=EARLY GROWTH. This is a measure of the relative height and size of a corn seedling at the 2-4 leaf stage of growth. This is a visual rating (1 to 9), with 1 being weak or slow growth, 5 being average growth and 9 being strong growth. Taller plants, wider leaves, more green mass and darker color constitute higher score.
ELITE INBRED. An inbred that contributed desirable qualities when used to produce commercial hybrids. An elite inbred may also be used in further breeding.
ERTLDG=EARLY ROOT LODGING. Early root lodging is the percentage of plants that do not root lodge prior to or around anthesis; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.
ERTLPN=Early root lodging. An estimate of the percentage of plants that do not root lodge prior to or around anthesis; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be considered as root lodged.
ERTLSC=EARLY ROOT LODGING SCORE. Score for severity of plants that lean from a vertical axis at an approximate 30-degree angle or greater, which typically results from strong winds prior to or around flowering recorded within 2 weeks of a wind event. Expressed as a 1 to 9 score with 9 being no lodging.
ESTCNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on per plot basis for the inbred or hybrid.
EYESPT=Eye Spot (Kabatiella zeae or Aureobasidium zeae). A 1 to 9 visual rating indicating the resistance to Eye Spot. A higher score indicates a higher resistance.
FUSERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusarium subglutinans). A 1 to 9 visual rating indicating the resistance to Fusarium ear rot. A higher score indicates a higher resistance.
GDU=Growing Degree Units. Using the Barger Heat Unit Theory, which assumes that maize growth occurs in the temperature range 50.degree. F.-86.degree. F. and that temperatures outside this range slow down growth; the maximum daily heat unit accumulation is 36 and the minimum daily heat unit accumulation is 0. The seasonal accumulation of GDU is a major factor in determining maturity zones.
GDUSHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##
The highest maximum temperature used is 86.degree. F. and the lowest minimum temperature used is 50.degree. F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.
GDUSLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.
GENOTYPE. Refers to the genetic constitution of a cell or organism.
GIBERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberelia zeae). A 1 to 9 visual rating indicating the resistance to Gibberella Ear Rot. A higher score indicates a higher resistance.
GIBROT=GIBBERELLA STALK ROT SCORE. Score of stalk rot severity due to Gibberella (Gibberella zeae). Expressed as a 1 to 9 score with 9 being highly resistant.
GLFSPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1 to 9 visual rating indicating the resistance to Gray Leaf Spot. A higher score indicates a higher resistance.
GOSWLT=Goss' Wilt (Corynebacterium nebraskense). A 1 to 9 visual rating indicating the resistance to Goss' Wilt. A higher score indicates a higher resistance.
GRNAPP=GRAIN APPEARANCE. This is a 1 to 9 rating for the general appearance of the shelled grain as it is harvested based on such factors as the color of harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.
H/POP=YIELD AT HIGH DENSITY. Yield ability at relatively high plant densities on 1-9 relative rating system with a higher number indicating the hybrid responds well to high plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to increased plant density.
HCBLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporium carbonum). A 1 to 9 visual rating indicating the resistance to Helminthosporium infection. A higher score indicates a higher resistance.
HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates the percentage of plants not infected.
HSKCVR=HUSK COVER. A 1 to 9 score based on performance relative to key checks, with a score of 1 indicating very short husks, tip of ear and kernels showing; 5 is intermediate coverage of the ear under most conditions, sometimes with thin husk; and a 9 has husks extending and closed beyond the tip of the ear. Scoring can best be done near physiological maturity stage or any time during dry down until harvested.
INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acre assuming drying costs of two cents per point above 15.5 percent harvest moisture and current market price per bushel.
INCOME/ACRE. Income advantage of hybrid to be patented over other hybrid on per acre basis.
INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1 over variety #2.
KSZDCD=KERNEL SIZE DISCARD. The percent of discard seed; calculated as the sum of discarded tip kernels and extra large kernels.
LINKAGE. Refers to a phenomenon wherein alleles on the same chromosome tend to segregate together more often than expected by chance if their transmission was independent.
LINKAGE DISEQUILIBRIUM. Refers to a phenomenon wherein alleles tend to remain together in linkage groups when segregating from parents to offspring, with a greater frequency than expected from their individual frequencies.
L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plant densities on a 1-9 relative system with a higher number indicating the hybrid responds well to low plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to low plant density.
LRTLDG=LATE ROOT LODGING. Late root lodging is the percentage of plants that do not root lodge after anthesis through harvest; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.
LRTLPN=LATE ROOT LODGING. Late root lodging is an estimate of the percentage of plants that do not root lodge after anthesis through harvest; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be considered as root lodged.
LRTLSC=LATE ROOT LODGING SCORE. Score for severity of plants that lean from a vertical axis at an approximate 30-degree angle or greater which typically results from strong winds after flowering. Recorded prior to harvest when a root-lodging event has occurred. This lodging results in plants that are leaned or "lodged" over at the base of the plant and do not straighten or "goose-neck" back to a vertical position. Expressed as a 1 to 9 score with 9 being no lodging.
MDMCPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus and MCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating the resistance to Maize Dwarf Mosaic Complex. A higher score indicates a higher resistance.
MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.
MSTADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 over variety #2 as calculated by: MOISTURE of variety #2-MOISTURE of variety #1=MOISTURE ADVANTAGE of variety #1.
NLFBLT=Northern Leaf Blight (Helminthosporium turcicum or Exserohilum turcicum). A 1 to 9 visual rating indicating the resistance to Northern Leaf Blight. A higher score indicates a higher resistance.
OILT=GRAIN OIL. Absolute value of oil content of the kernel as predicted by Near-infrared Transmittance and expressed as a percent of dry matter.
PEDIGREE DISTANCE. Relationship among generations based on their ancestral links as evidenced in pedigrees. May be measured by the distance of the pedigree from a given starting point in the ancestry.
PLTHT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in centimeters.
POLSC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount of pollen shed. The higher the score the more pollen shed.
POLWT=POLLEN WEIGHT. This is calculated by dry weight of tassels collected as shedding commences minus dry weight from similar tassels harvested after shedding is complete.
POP K/A=PLANT POPULATIONS. Measured as 1000s per acre.
POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage of variety #1 over variety #2 as calculated by PLANT POPULATION of variety #2-PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety #1.
PRM=PREDICTED RELATIVE MATURITY. This trait, predicted relative maturity, is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is also referred to as the Comparative Relative Maturity Rating System that is similar to the Minnesota Relative Maturity Rating System.
PRMSHD=A relative measure of the growing degree units (GDU) required to reach 50% pollen shed. Relative values are predicted values from the linear regression of observed GDU's on relative maturity of commercial checks.
PROT=GRAIN PROTEIN. Absolute value of protein content of the kernel as predicted by Near-Infrared Transmittance and expressed as a percent of dry matter.
RTLDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.
RTLADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1 over variety #2.
SCTGRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.
SDGVGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.
SEL IND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A maize breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.
SLFBLT=SOUTHERN LEAF BLIGHT (Helminthosporium maydis or Bipolaris maydis). A 1 to 9 visual rating indicating the resistance to Southern Leaf Blight. A higher score indicates a higher resistance.
SOURST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual rating indicating the resistance to Southern Rust. A higher score indicates a higher resistance.
STAGRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.
STDADV=STALK STANDING ADVANTAGE. The advantage of variety #1 over variety #2 for the trait STK CNT.
STKCNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.
STKLDG=STALK LODGING REGULAR. This is the percentage of plants that did not stalk lodge (stalk breakage) at regular harvest (when grain moisture is between about 20 and 30%) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.
STKLDL=LATE STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) at or around late season harvest (when grain moisture is between about 15 and 18%) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.
STKLDS=STALK LODGING SCORE. A plant is considered as stalk lodged if the stalk is broken or crimped between the ear and the ground. This can be caused by any or a combination of the following: strong winds late in the season, disease pressure within the stalks, ECB damage or genetically weak stalks. This trait should be taken just prior to or at harvest. Expressed on a 1 to 9 scale with 9 being no lodging.
STLPCN=STALK LODGING REGULAR. This is an estimate of the percentage of plants that did not stalk lodge (stalk breakage) at regular harvest (when grain moisture is between about 20 and 30%) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.
STRT=GRAIN STARCH. Absolute value of starch content of the kernel as predicted by Near-infrared Transmittance and expressed as a percent of dry matter.
STWWLT=Stewart's Wilt (Erwinia stewartii). A 1 to 9 visual rating indicating the resistance to Stewart's Wilt. A higher score indicates a higher resistance.
TASBLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at the time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.
TASSZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.
TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.
TEXEAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).
TILLER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data are given as a percentage of tillers: number of tillers per plot divided by number of plants per plot.
TSTWT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grain in pounds for a given volume (bushel).
TSWADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety #1 over variety #2.
WIN M %=PERCENT MOISTURE WINS.
WIN Y %=PERCENT YIELD WINS.
YIELD BU/A=YIELD (BUSHELS/ACRE). Yield of the grain at harvest in bushels per acre adjusted to 15% moisture.
YLDADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety #2 as calculated by: YIELD of variety #1-YIELD variety #2=yield advantage of variety #1.
YLDSC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.
Definitions for Area of Adaptability
When referring to area of adaptability, such term is used to describe the location with the environmental conditions that would be well suited for this maize line. Area of adaptability is based on a number of factors, for example: days to maturity, insect resistance, disease resistance, and drought resistance. Area of adaptability does not indicate that the maize line will grow in every location within the area of adaptability or that it will not grow outside the area. Central Corn Belt: Iowa, Illinois, Indiana Drylands: non-irrigated areas of North Dakota, South Dakota, Nebraska, Kansas, Colorado and Oklahoma Eastern U.S.: Ohio, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia North central U.S.: Minnesota and Wisconsin Northeast: Michigan, New York, Vermont, and Ontario and Quebec Canada Northwest U.S.: North Dakota, South Dakota, Wyoming, Washington, Oregon, Montana, Utah, and Idaho South central U.S.: Missouri, Tennessee, Kentucky, and Arkansas Southeast U.S.: North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, and Louisiana Southwest U.S.: Texas, Oklahoma, New Mexico, and Arizona Western U.S.: Nebraska, Kansas, Colorado, and California Maritime Europe: France, Germany, Belgium and Austria
DETAILED DESCRIPTION OF THE INVENTION
Inbred maize lines are typically developed for use in the production of hybrid maize lines. Inbred maize lines need to be highly homogeneous, substantially homozygous and reproducible to be useful as parents of commercial hybrids. There are many analytical methods available to determine the homozygotic stability and the identity of these inbred lines.
The oldest and most traditional method of analysis is the observation of phenotypic traits. The data is usually collected in field experiments over the life of the maize plants to be examined. Phenotypic characteristics most often observed are for traits associated with plant morphology, ear and kernel morphology, insect and disease resistance, maturity, and yield.
In addition to phenotypic observations, the genotype of a plant can also be examined. A plant's genotype can be used to identify plants of the same variety or a related variety. For example, the genotype can be used to determine the pedigree of a plant. There are many laboratory-based techniques available for the analysis, comparison and characterization of plant genotype; among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs) which are also referred to as Microsatellites, and Single Nucleotide Polymorphisms (SNPs).
Isozyme Electrophoresis and RFLPs as discussed in Lee, M., "Inbred Lines of Maize and Their Molecular Markers," The Maize Handbook, (Springer-Verlag, New York, Inc. 1994, at 423-432) incorporated herein by reference, have been widely used to determine genetic composition. Isozyme Electrophoresis has a relatively low number of available markers and a low number of allelic variants among maize inbreds. RFLPs allow more discrimination because they have a higher degree of allelic variation in maize and a larger number of markers can be found. Both of these methods have been eclipsed by SSRs as discussed in Smith et al., "An evaluation of the utility of SSR loci as molecular markers in maize (Zea mays L.): comparisons with data from RFLPs and pedigree", Theoretical and Applied Genetics (1997) vol. 95 at 163-173 and by Pejic et al., "Comparative analysis of genetic similarity among maize inbreds detected by RFLPs, RAPDs, SSRs, and AFLPs," Theoretical and Applied Genetics (1998) at 1248-1255 incorporated herein by reference. SSR technology is more efficient and practical to use than RFLPs; more marker loci can be routinely used and more alleles per marker locus can be found using SSRs in comparison to RFLPs. Single Nucleotide Polymorphisms may also be used to identify the unique genetic composition of the invention and progeny lines retaining that unique genetic composition. Various molecular marker techniques may be used in combination to enhance overall resolution.
Maize DNA molecular marker linkage maps have been rapidly constructed and widely implemented in genetic studies. One such study is described in Boppenmaier, et al., "Comparisons among strains of inbreds for RFLPs", Maize Genetics Cooperative Newsletter, 65:1991, pg. 90, is incorporated herein by reference.
Inbred maize line PH4CV is a yellow, dent maize inbred that is well suited to be used as either the female or male in production of the first generation F1 maize hybrids. Inbred maize line PH4CV is best adapted to the Central Corn Belt, Eastern, Southcentral, and Southeast areas of the United States and can be used to produce hybrids with approximately a 113 maturity based on the Comparative Relative Maturity Rating System for harvest moisture of grain. Inbred maize line PH4CV demonstrates good female yield and good Southern Corn Leaf Blight, Stewarts Bacterial Leaf Blight and Gray Leaf Spot tolerance as an inbred per se. Inbred maize line PH4CV also has above average tolerance to Diplodia, Fusarium, and Gibberella ear rots as an inbred per se. In hybrid combination, inbred PH4CV demonstrates high grain yield, good foliar disease tolerance, and short ear and plant height.
The inbred has shown uniformity and stability within the limits of environmental influence for all the traits as described in the Variety Description Information (Table 1) that follows. The inbred has been self-pollinated and ear-rowed a sufficient number of generations with careful attention paid to uniformity of plant type to ensure the homozygosity and phenotypic stability necessary to use in commercial production. The line has been increased both by hand and in isolated fields with continued observation for uniformity. No variant traits have been observed or are expected in PH4CV.
Inbred maize line PH4CV, being substantially homozygous, can be reproduced by planting seeds of the line, growing the resulting maize plants under self-pollinating or sib-pollinating conditions with adequate isolation, and harvesting the resulting seed using techniques familiar to the agricultural arts.
TABLE 1 VARIETY DESCRIPTION INFORMATION VARIETY = PH4CV 1. TYPE: 2 1 = Sweet 2 = Dent 3 = Flint 4 = Flour 5 = Pop 6 = Ornamental 2. MATURITY: DAYS HEAT UNITS 074 1,439.3 From emergence to 50% of plants in silk 074 1,451.8 From emergence to 50% of plants in pollen 002 0,067.7 From 10% to 90% pollen shed From 50% silk to harvest at 25% moisture Standard Sample 3. PLANT: Deviation Size 0,221.8 cm Plant Height (to tassel tip) 12.41 45 0,078.3 cm Ear Height (to base of top ear 7.84 45 node) 0,015.2 cm Length of Top Ear Internode 1.07 45 0.0 Average Number of Tillers 0.03 9 0.9 Average Number of Ears per Stalk 0.11 9 3.0 Anthocyanin of Brace Roots: 1 = Absent 2 = Faint 3 = Moderate 4 = Dark 5 = Very Dark Standard Sample 4. LEAF: Deviation Size 010.5 cm Width of Ear Node Leaf 0.75 45 077.3 cm Length of Ear Node Leaf 3.17 45 07.1 Number of leaves above top ear 0.52 45 15.4 Degrees Leaf Angle (measure from 4.68 45 2nd leaf above ear at anthesis to stalk above leaf) 03 Leaf Color Dark Green ~undefinedMC) 7.5GY34 1.2 Leaf Sheath Pubescence (Rate on scale from 1 = none to 9 = like peach fuzz) Marginal Waves (Rate on scale from 1 = none to 9 = many) Longitudinal Creases (Rate on scale from 1 = none to 9 = many) Standard Sample 5. TASSEL: Deviation Size 04.7 Number of Primary Lateral 1.63 45 Branches 015.5 Branch Angle from Central Spike 6.20 45 50.4 cm Tassel Length (from top leaf collar 3.87 45 to tassel tip) 5.2 Pollen Shed (rate on scale from 0 = male sterile to 9 = heavy shed) 07 Anther Color Yellow ~undefinedMC) 10Y96 01 Glume Color Light Green ~undefinedMC) 5GY56 1.0 Bar Glumes (Glume Bands): 1 = Absent 2 = Present 17 cm Peduncle Length (cm. from top leaf to basal branches) 6a. EAR (Unhusked Data): 11 Silk Color (3 days after emergence) Pink ~undefinedMC) 2.5R58 1 Fresh Husk Color (25 days after 50% Light Green ~undefinedMC) 5GY56 21 Dry Husk Color (65 days after 50% silking) Buff ~undefinedMC) 2.5Y92 3 Position of Ear at Dry Husk Stage: 1 = Upright 2 = Horizontal 3 = Pendant 5 Husk Tightness (Rate of Scale from 1 = very loose to 9 = very tight) 2 Husk Extension (at harvest): 1 = Short (ears exposed) 2 = Medium (<8 cm) 3 = Long (8-10 cm beyond ear tip) 4 = Very Long (>10 cm) Standard Sample 6b. EAR (Husked Ear Data): Deviation Size 15 cm Ear Length 0.88 45 42 mm Ear Diameter at mid-point 2.01 45 111 gm Ear Weight 23.87
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6897363.PN.&OS=PN/6897363&RS=PN/6897363
United States Patent 6,897,363
Barker May 24, 2005
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Inbred maize line PH4CV
Abstract
An inbred maize line, designated PH4CV, the plants and seeds of inbred maize line PH4CV, methods for producing a maize plant, either inbred or hybrid, produced by crossing the inbred maize line PH4CV with another maize plant, and hybrid maize seeds and plants produced by crossing the inbred line PH4CV with another maize line or plant and to methods for producing a maize plant containing in its genetic material one or more transgenes and to the transgenic maize plants produced by that method. This invention also relates to inbred maize lines derived from inbred maize line PH4CV, to methods for producing other inbred maize lines derived from inbred maize line PH4CV and to the inbred maize lines derived by the use of those methods.
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Inventors: Barker; Thomas Charles (York, NE)
Assignee: Pioneer Hi-Bred International, Inc. (Johnston, IA)
Appl. No.: 10/271,942
Filed: October 15, 2002
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Current U.S. Class: 800/320.1 ; 435/412; 800/275; 800/278; 800/279; 800/281; 800/298; 800/300.1; 800/301; 800/302; 800/303
Current International Class: A01H 5/10 (20060101); A01H 001/00 (); A01H 004/00 (); A01H 005/00 (); A01H 005/10 (); C12N 015/82 ()
Field of Search: 800/320.1,266,275,278,279,284,298,300.1,301,302,303 435/412
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References Cited [Referenced By]
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U.S. Patent Documents
5436390 July 1995 Oestreich
5563325 October 1996 Morrow
5792911 August 1998 Anderson
5850010 December 1998 Anderson
6333453 December 2001 Henke
Other References
Plant Variety Protection Certificate No. 9500200 for Corn PHBE2, issued Aug. 13, 1996. .
Plant Variety Protection Certificate No. 9100097 for Corn PHRO3, issued Apr. 30, 1992. .
Plant Variety Protection Certificate No. 200000242 for Corn, Field PH1BC, issued Jan. 13, 2002. .
Plant Variety Protection Certificate No. 200000243 for Corn, Field PH2EJ, issued Feb., 5, 2002. .
Plant Variety Protection Certificate No. 9600200 for Corn PH56C, issued Jul. 30, 1999. .
Plant Variety Protection Certificate No. 9700223 for Corn, Field, PH24M, issued Apr., 24, 2001..
Primary Examiner: Kruse; David H
Attorney, Agent or Firm: McKee, Voorhees & Sease, P.L.C.
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Parent Case Text
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit of the priority date of U.S. Patent Application Ser. No. 60/352,317 filed Jan. 28, 2002, which is hereby incorporated herein by reference.
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Claims
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What is claimed is:
1. A seed of maize inbred line designated PH4CV, representative seed of said line having been deposited under ATCC Accession No. PTA-4673.
2. A maize plant, or a part thereof, produced by growing the seed of claim 1.
3. The maize plant of claim 2, wherein said plant has been detasseled.
4. A tissue culture of regenerable cells produced from the plant of claim 2.
5. A protoplast produced from the tissue culture of claim 4.
6. The tissue culture of claim 4, wherein cells of the tissue culture are produced from a tissue selected from the group consisting of leaf, pollen, embryo, root, root tip, anther, silk, flower, kernel, ear, cob, husk and stalk.
7. A maize plant regenerated from the tissue culture of claim 4, said plant having all the morphological and physiological characteristics of inbred line PH4CV, representative seed of said inbred line having been deposited under ATCC Accession No. PTA-4673.
8. A method for producing an F1 hybrid maize seed, comprising crossing the plant of claim 2 with a different maize plant and harvesting the resultant F1 hybrid maze seed.
9. A method of producing a male sterile maize plant comprising transforming the maize plant of claim 2 with a nucleic acid molecule that confers male sterility.
10. A male sterile maize plant produced by the method of claim 9.
11. A method of producing an herbicide resistant maize plant comprising transforming the maize plant of claim 2 with a transgene that confers herbicide resistance.
12. An herbicide resistant maize plant produced by the method of claim 11.
13. The maize plant of claim 12, wherein the transgene confers resistance to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, glufosinate, L-phosphinothricin, triazine and benzonitrile.
14. A method of producing an insect resistant maize plant comprising transforming the maize plant of claim 2 with a transgene that confers insect resistance.
15. An insect resistant maize plant produced by the method of claim 14.
16. The maize plant of claim 15, wherein the transgene encodes a Bacillus thuringiensis endotoxin.
17. A method of producing a disease resistant maize plant comprising transforming the maize plant of claim 2 with a transgene that confers disease resistance.
18. A disease resistant maize plant produced by the method of claim 17.
19. A method of producing a maize plant with decreased phytate content comprising transforming the maize plant of claim 2 with a transgene encoding phytase.
20. A maize plant with decreased phytate content produced by the method of claim 19.
21. A method of producing a maize plant with modified fatty acid metabolism or modified carbohydrate metabolism comprising transforming the maize plant of claim 2 with a transgene encoding a protein selected from the group consisting of fructosyltransferase, levansucrase, alpha-amylase, invertase and starch branching enzyme or encoding an antisense of stearyl-ACP desaturase.
22. A maize plant, with modified fatty acid metabolism or modified carbohydrate metabolism, produced by the method of claim 21.
23. The maize plant of 22 wherein the transgene confers a trait selected from the group consisting of waxy starch and increased amylose starch.
24. A maize plant, or part thereof, having all the physiological and morphological characteristics of the inbred line PH4CV, representative seed of said inbred line having been deposited under ATCC Accession No. PTA-4673.
25. A method of introducing a desired trait into maize inbred line PH4CV comprising: (a) crossing PH4CV plants grown from PH4CV seed, representative seed of which has been deposited under ATCC Accession No. PTA-4673, with plants of another maize line that comprise a desired trait to produce F1 progeny plants, wherein the desired trait is selected from the group consisting of male sterility, herbicide resistance, insect resistance, disease resistance and waxy starch; (b) selecting F1 progeny plants that have the desired trait to produce selected F1 progeny plants; (c) crossing the selected progeny plants with the PH4CV plants to produce backcross progeny plants; (d) selecting for backcross progeny plants that have the desired trait and physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 to produce selected backcross progeny plants; and (e) repeating steps (c) and (d) three or more times in succession to produce selected fourth or higher backcross progeny plants that comprise the desired trait and all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
26. A plant produced by the method of claim 25, wherein the plant has the desired trait and all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
27. The plant of claim 26 wherein the desired trait is herbicide resistance and the resistance is conferred to an herbicide selected from the group consisting of imidazolinone, sulfonylurea, glyphosate, glufosinate, L-phosphinothricin, triazine and benzonitrile.
28. The plant of claim 26 wherein the desired trait is insect resistance and the insect resistance is conferred by a transgene encoding a Bacillus thuringiensis endotoxin.
29. The plant of claim 26 wherein the desired trait is male sterility and the trait is conferred by a cytoplasmic nucleic acid molecule that confers male sterility.
30. A method of modifying fatty acid metabolism, phytic acid metabolism or carbohydrate in maize inbred line PH4CV comprising: (a) crossing PH4CV plants grown from PH4CV seed, representative seed of which has been deposited under ATCC Accession No. PTA-4673, with plants of another maize line that comprise a nucleic acid molecule encoding an enzyme selected from the group consisting of phytase, fructosyltransferase, levansucrase, alpha-amylase, invertase and starch branching enzyme or encoding an antisense of stearyl-ACP desaturase; (b) selecting F1 progeny plants that have said nucleic acid molecule to produce selected F1 progeny plants; (c) crossing the selected progeny plants with the PH4CV plants to produce backcross progeny plants; (d) selecting for backcross progeny plants that have said nucleic acid molecule and physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 to produce selected backcross progeny plants; and (e) repeating steps (c) and (d) three or more times in succession to produce selected fourth or higher backcross progeny plants that comprise said nucleic acid molecule and have all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
31. A plant, with modified fatty acid metabolism, modified phytic acid metabolism, or modified carbohydrate metabolism, produced by the method of claim 30, wherein the plant comprises the nucleic acid molecule and has all of the physiological and morphological characteristics of maize inbred line PH4CV listed in Table 1 as determined at the 5% significance level when grown in the same environmental conditions.
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Description
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FIELD OF THE INVENTION
This invention is in the field of maize breeding, specifically relating to an inbred maize line designated PH4CV.
BACKGROUND OF THE INVENTION
The goal of plant breeding is to combine in a single variety or hybrid, various desirable traits. For field crops, these traits may include resistance to diseases and insects, tolerance to heat and drought, reducing the time to crop maturity, greater yield, and better agronomic quality. With mechanical harvesting of many crops, uniformity of plant characteristics such as germination and stand establishment, growth rate, maturity, and plant and ear height, is important.
Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is sib-pollinated when individuals within the same family or line are used for pollination. A plant is cross-pollinated if the pollen comes from a flower on a different plant from a different family or line. The terms "cross-pollination" and "out-cross" as used herein do not include self-pollination or sib-pollination.
Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two different homozygous lines produces a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two plants, each heterozygous at a number of gene loci will produce a population of hybrid plants that differ genetically and will not be uniform.
Maize (zea mays L.), often referred to as corn in the United States, can be bred by both self-pollination and cross-pollination techniques. Maize has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in maize when wind blows pollen from the tassels to the silks that protrude from the tops of the ears.
A reliable method of controlling male fertility in plants offers the opportunity for improved plant breeding. This is especially true for development of maize hybrids, which relies upon some sort of male sterility system. There are several ways in which a maize plant can be manipulated so that it is male sterile. These include use of manual or mechanical emasculation (or detasseling), use of cytoplasmic genetic or nuclear genetic male sterility, use of gametocides and is the like.
Hybrid maize seed is typically produced by a male sterility system incorporating manual or mechanical detasseling. Alternate strips of two maize inbreds are planted in a field, and the pollen-bearing tassels are removed from one of the inbreds (female). Provided that there is sufficient isolation from sources of foreign maize pollen, the ears of the detasseled inbred will be fertilized only from the other inbred (male), and the resulting seed is therefore hybrid and will form hybrid plants.
The laborious detasseling process can be avoided by using cytoplasmic male-sterile (CMS) inbreds. Plants of a CMS inbred are male sterile as a result of factors resulting from the cytoplasmic, as opposed to the nuclear, genome. Thus, this characteristic is inherited exclusively through the female parent in maize plants, since only the female provides cytoplasm to the fertilized seed. CMS plants are fertilized with pollen from another inbred that is not male-sterile. Pollen from the second inbred may or may not contribute genes that make the hybrid plants male-fertile. The same hybrid seed, a portion produced from detasseled fertile maize and a portion produced using the CMS system, can be blended to insure that adequate pollen loads are available for fertilization when the hybrid plants are grown.
There are several methods of conferring genetic male sterility available, such as multiple mutant genes at separate locations within the genome that confer male sterility, as disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar et al. and chromosomal translocations as described by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. These and all patents, patent applications and publications referred to herein are incorporated by reference. In addition to these methods, Albertsen et al., of Pioneer Hi-Bred, U.S. Pat. No. 5,432,068, have developed a system of nuclear male sterility which includes: identifying a gene which is critical to male fertility; silencing this native gene which is critical to male fertility; removing the native promoter from the essential male fertility gene and replacing it with an inducible promoter; inserting this genetically engineered gene back into the plant; and thus creating a plant that is male sterile because the inducible promoter is not "on" resulting in the male fertility gene not being transcribed. Fertility is restored by inducing, or turning "on", the promoter, which in turn allows the gene that confers male fertility to be transcribed.
These, and the other methods of conferring genetic male sterility in the art, each possess their own benefits and drawbacks. Some other methods use a variety of approaches such as delivering into the plant a gene encoding a cytotoxic substance associated with a male tissue specific promoter or an antisense system in which a gene critical to fertility is identified and an antisense to that gene is inserted in the plant (see: Fabinjanski, et al. EPO 89/3010153.8 publication no. 329,308 and PCT application PCT/CA90/00037 published as WO 90/08828).
Another system for controlling male sterility makes use of gametocides. Gametocides are not a genetic system, but rather a topical application of chemicals. These chemicals affect cells that are critical to male fertility. The application of these chemicals affects fertility in the plants only for the growing season in which the gametocide is applied (see Carlson, Glenn R., U.S. Pat. No. 4,936,904). Application of the gametocide, timing of the application and genotype specificity often limit the usefulness of the approach and it is not appropriate in all situations.
Development of Maize Inbred Lines
The use of male sterile inbreds is but one factor in the production of maize hybrids. Plant breeding techniques known in the art and used in a maize plant breeding program include, but are not limited to, recurrent selection, backcrossing, pedigree breeding, restriction fragment length polymorphism enhanced selection, genetic marker enhanced selection, making double haploids, and transformation. Often a combination of these techniques is used. The development of maize hybrids in a maize plant breeding program requires, in general, the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses.
Maize plant breeding programs combine the genetic backgrounds from two or more inbred lines or various other germplasm sources into breeding populations from which new inbred lines are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred lines and the hybrids from these crosses are evaluated to determine which of those have commercial potential. Plant breeding and hybrid development, as practiced in a maize plant breeding program developing significant genetic advancement, are expensive and time-consuming processes.
Pedigree breeding starts with the crossing of two genotypes, such as two elite inbred lines, each of which may have one or more desirable characteristics that is lacking in the other or which complements the other. If the two original parents do not provide all the desired characteristics, other sources can be included in the breeding population. In the pedigree method, superior plants are selfed and selected in successive filial generations. In the succeeding filial generations the heterozygous condition gives way to homogeneous lines as a result of self-pollination and selection. Typically in the pedigree method of breeding, five or more successive filial generations of selfing and selection is practiced: F.sub.1.fwdarw.F.sub.2 ; F.sub.2.fwdarw.F.sub.3 ; F.sub.3.fwdarw.F.sub.4 ; F.sub.4.fwdarw.F.sub.5, etc. After a sufficient amount of inbreeding, successive filial generations will serve to increase seed of the developed inbred. Preferably, an inbred line comprises homozygous alleles at about 95% or more of its loci.
Backcrossing can be used to improve an inbred line and a hybrid that is made using those inbreds. Backcrossing can be used to transfer a specific desirable trait from one line, the donor parent, to an inbred called the recurrent parent which has overall good agronomic characteristics yet lacks that desirable trait. This transfer of the desirable trait into an inbred with overall good agronomic characteristics can be accomplished by first crossing a recurrent parent and a donor parent (non-recurrent parent). The progeny of this cross is then mated back to the recurrent parent followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent as well as selection for the characteristics of the recurrent parent. Typically after four or more backcross generations with selection for the desired trait and the characteristics of the recurrent parent, the progeny will contain essentially all genes of the recurrent parent except for the genes controlling the desired trait. However, the number of backcross generations can be less if molecular markers are used during selection or elite germplasm is used as the donor parent. The last backcross generation is then selfed to give pure breeding progeny for the gene(s) being transferred. Backcrossing can also be used in conjunction with pedigree breeding to develop new inbred lines. For example, an F1 can be created that is backcrossed to one of its parent lines to create a BC1, BC2, BC3, etc. Progeny are selfed and selected so that the newly developed inbred has many of the attributes of the recurrent parent and some of the desired attributes of the non-recurrent parent. This approach leverages the value and strengths of the recurrent parent for use in new hybrids and breeding which has very significant value for a breeder.
Recurrent selection is a method used in a plant breeding program to improve a population of plants. The method entails individual plants cross-pollinating with each other to form progeny, which are then grown. The superior progeny are then selected by any number of methods, which include individual plant, half-sib progeny, full-sib progeny, selfed progeny and topcrossing. The selected progeny are cross-pollinated with each other to form progeny for another population. This population is planted and again superior plants are selected to cross-pollinate with each other. Recurrent selection is a cyclical process and therefore can be repeated as many times as desired. The objective of recurrent selection is to improve the traits of a population. The improved population can then be used as a source of breeding material to obtain inbred lines to be used in hybrids or used as parents for a synthetic cultivar. A synthetic cultivar is the resultant progeny formed by the intercrossing of several selected inbreds. Mass selection is a useful technique when used in conjunction with molecular marker enhanced selection.
Mutation breeding is one of the many methods of introducing new traits into inbred lines. Mutations that occur spontaneously or are artificially induced can be useful sources of variability for a plant breeder. The goal of artificial mutagenesis is to increase the rate of mutation for a desired characteristic. Mutation rates can be increased by many different means including temperature, long-term seed storage, tissue culture conditions, radiation; such as X-rays, Gamma rays (e.g. cobalt 60 or cesium 137), neutrons, (produce of nuclear fission by uranium 235 on an atomic reactor), Beta radiation (emitted from radioisotopes such as phosphorus 32 or carbon 14), or ultraviolet radiation (preferably from 2500 to 2900 nm), or chemical mutagens (such as base analogues (5-bromo-uracil), related compounds (8-ethoxy caffeine), antibiotics (streptonigrin), alkylating agents (sulfur mustards, nitrogen mustards, epoxides, ethylenamines, sulfates, sulfonates, sulfones, lactones), azide, hydroxylamine, nitrous acid, or acridines. Once a desired trait is observed through mutagenesis the trait may then be incorporated into existing germplasm by traditional breeding techniques. Details of mutation breeding can be found in "Principals of Cultivar Development" Fehr, 1993 Macmillan Publishing Company the disclosure of which is incorporated herein by reference.
Molecular markers, which includes markers identified through the use of techniques such as Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs) and Single Nucleotide Polymorphisms (SNPs), may be used in plant breeding methods. One use of molecular markers is Quantitative Trait Loci (QTL) mapping. QTL mapping is the use of markers, which are known to be closely linked to alleles that have measurable effects on a quantitative trait. Selection in the breeding process is based upon the accumulation of markers linked to the positive effecting alleles and/or the elimination of the markers linked to the negative effecting alleles from the plant's genome.
Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers closely linked to alleles or markers containing sequences within the actual alleles of interest can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select for the genome of the recurrent parent and against the genome of the donor parent. Using this procedure can minimize the amount of genome from the donor parent that remains in the selected plants. It can also be used to reduce the number of crosses back to the recurrent parent needed in a backcrossing program. The use of molecular markers in the selection process is often called genetic marker enhanced selection.
The production of double haploids can also be used for the development of inbreds in the breeding program. Double haploids are produced by the doubling of a set of chromosomes (1N) from a heterozygous plant to produce a completely homozygous individual. For example, see Wan et al., "Efficient Production of Doubled Haploid Plants Through Colchicine Treatment of Anther-Derived Maize Callus", Theoretical and Applied Genetics, 77:889-892, 1989. This can be advantageous because the process omits the generations of selfing needed to obtain a homozygous plant from a heterozygous source.
Development of Maize Hybrids
A single cross maize hybrid results from the cross of two inbred lines, each of which has a genotype that complements the genotype of the other. The hybrid progeny of the first generation is designated F.sub.1. In the development of commercial hybrids in a maize plant breeding program, only the F.sub.1 hybrid plants are sought. F.sub.1 hybrids are more vigorous than their inbred parents. This hybrid vigor, or heterosis, can be manifested in many polygenic traits, including increased vegetative growth and increased yield.
The development of a maize hybrid in a maize plant breeding program involves three steps: (1) the selection of plants from various germplasm pools for initial breeding crosses; (2) the selfing of the selected plants from the breeding crosses for several generations to produce a series of inbred lines, which, although different from each other, breed true and are highly uniform; and (3) crossing the selected inbred lines with different inbred lines to produce the hybrids. During the inbreeding process in maize, the vigor of the lines decreases. Vigor is restored when two different inbred lines are crossed to produce the hybrid. An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between a defined pair of inbreds will always be the same. Once the inbreds that give a superior hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained.
A single cross hybrid is produced when two inbred lines are crossed to produce the F.sub.1 progeny. A double cross hybrid is produced from four inbred lines crossed in pairs (A.times.B and C.times.D) and then the two F.sub.1 hybrids are crossed again (A.times.B).times.(C.times.D). A three-way cross hybrid is produced from three inbred lines where two of the inbred lines are crossed (A.times.B) and then the resulting F.sub.1 hybrid is crossed with the third inbred (A.times.B).times.C. Much of the hybrid vigor and uniformity exhibited by F.sub.1 hybrids is lost in the next generation (F.sub.2). Consequently, seed produced from hybrids is not used for planting stock.
Hybrid seed production requires elimination or inactivation of pollen produced by the female parent. Incomplete removal or inactivation of the pollen provides the potential for self-pollination. This inadvertently self-pollinated seed may be unintentionally harvested and packaged with hybrid seed. Also, because the male parent is grown next to the female parent in the field there is the very low probability that the male selfed seed could be unintentionally harvested and packaged with the hybrid seed. Once the seed from the hybrid bag is planted, it is possible to identify and select these self-pollinated plants. These self-pollinated plants will be genetically equivalent to one of the inbred lines used to produce the hybrid. Though the possibility of inbreds being included hybrid seed bags exists, the occurrence is very low because much care is taken to avoid such inclusions. It is worth noting that hybrid seed is sold to growers for the production of grain or forage and not for breeding or seed production.
These self-pollinated plants can be identified and selected by one skilled in the art due to their decreased vigor when compared to the hybrid. Inbreds are identified by their less vigorous appearance for vegetative and/or reproductive characteristics, including shorter plant height, small ear size, ear and kernel shape, cob color, or other characteristics.
Identification of these self-pollinated lines can also be accomplished through molecular marker analyses. See, "The Identification of Female Selfs in Hybrid Maize: A Comparison Using Electrophoresis and Morphology", Smith, J. S. C. and Wych, R. D., Seed Science and Technology 14, pp. 1-8 (1995), the disclosure of which is expressly incorporated herein by reference. Through these technologies, the homozygosity of the self-pollinated line can be verified by analyzing allelic composition at various loci along the genome. Those methods allow for rapid identification of the invention disclosed herein. See also, "Identification of Atypical Plants in Hybrid Maize Seed by Postcontrol and Electrophoresis" Sarca, V. et al., Probleme de Genetica Teoritica si Aplicata Vol. 20 (1) p. 29-42.
As is readily apparent to one skilled in the art, the foregoing are only some of the various ways by which the inbred can be obtained by those looking to use the germplasm. Other means are available, and the above examples are illustrative only.
Maize is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop high-yielding maize hybrids that are agronomically sound based on stable inbred lines. The reasons for this goal are obvious: to maximize the amount of grain produced with the inputs used and minimize susceptibility of the crop to pests and environmental stresses. To accomplish this goal, the maize breeder must select and develop superior inbred parental lines for producing hybrids. This requires identification and selection of genetically unique individuals that occur in a segregating population. The segregating population is the result of a combination of crossover events plus the independent assortment of specific combinations of alleles at many gene loci that results in specific genotypes. The probability of selecting any one individual with a specific genotype from a breeding cross is infinitesimal due to the large number of segregating genes and the unlimited recombinations of these genes, some of which may be closely linked. However, the genetic variation among individual progeny of a breeding cross allows for the identification of rare and valuable new genotypes. These new genotypes are neither predictable nor incremental in value, but rather the result of manifested genetic variation combined with selection methods, environments and the actions of the breeder. Once identified, it is possible to utilize routine and predictable breeding methods to develop progeny that retain the rare and valuable new genotypes developed by the initial breeder.
Even if the entire genotypes of the parents of the breeding cross were characterized and a desired genotype known, only a few if any individuals having the desired genotype may be found in a large segregating F.sub.2 population. It would be very unlikely that a breeder of ordinary skill in the art would able to recreate the same line twice from the very same original parents, as the breeder is unable to direct how the genomes combine or how they will interact with the environmental conditions. This unpredictability results in the expenditure of large amounts of research resources in the development of a superior new maize inbred line. Once such a line is developed its value to society is substantial since it is important to advance the germplasm base as a whole in order to maintain or improve traits such as yield, disease resistance, pest resistance and plant performance in extreme conditions.
A breeder uses various methods to help determine which plants should be selected from the segregating populations and ultimately which inbred lines will be used to develop hybrids for commercialization. In addition to the knowledge of the germplasm and other skills the breeder uses, a part of the selection process is dependent on experimental design coupled with the use of statistical analysis. Experimental design and statistical analysis are used to help determine which plants, which family of plants, and finally which inbred lines and hybrid combinations are significantly better or different for one or more traits of interest. Experimental design methods are used to assess error so that differences between two inbred lines or two hybrid lines can be more accurately determined. Statistical analysis includes the calculation of mean values, determination of the statistical significance of the sources of variation, and the calculation of the appropriate variance components. Either a five or a one percent significance level is customarily used to determine whether a difference that occurs for a given trait is real or due to the environment or experimental error.
One of ordinary skill in the art of plant breeding would know how to evaluate the traits of two plant varieties to determine if there is no significant difference between the two traits expressed by those varieties. For example, see Fehr, Walt, Principles of Cultivar Development, p. 261-286 (1987) which is incorporated herein by reference. Mean trait values may be used to determine whether trait differences are significant, and preferably the traits are measured on plants grown under the same environmental conditions.
Combining ability of a line, as well as the performance of the line per se, is a factor in the selection of improved maize inbreds. Combining ability refers to a line's contribution as a parent when crossed with other lines to form hybrids. The hybrids formed for the purpose of selecting superior lines are designated testcrosses. One way of measuring combining ability is by using breeding values. Breeding values are based in part on the overall mean of a number of testcrosses. This mean is then adjusted to remove environmental effects and it is adjusted for known genetic relationships among the lines.
SUMMARY OF THE INVENTION
According to the invention, there is provided a novel inbred maize line, designated PH4CV. This invention thus relates to the seeds of inbred maize line PH4CV, to the plants of inbred maize line PH4CV, to plant parts of inbred maize line PH4CV, to methods for producing a maize plant produced by crossing the inbred maize line PH4CV with another maize plant, including a plant that is part of a synthetic or natural population, and to methods for producing a maize plant containing in its genetic material one or more transgenes and to the transgenic maize plants and plant parts produced by that method. This invention also relates to inbred maize lines and plant parts derived from inbred maize line PH4CV, to methods for producing other inbred maize lines derived from inbred maize line PH4CV and to the inbred maize lines and their parts derived by the use of those methods. This invention further relates to hybrid maize seeds, plants, and plant parts produced by crossing the inbred line PH4CV with another maize line.
Definitions
Certain definitions used in the specification are provided below. Also in the examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided. NOTE: ABS is in absolute terms and % MN is percent of the mean for the experiments in which the inbred or hybrid was grown. PCT designates that the trait is calculated as a percentage. % NOT designates the percentage of plants that did not exhibit a trait. For example, STKLDG % NOT is the percentage of plants in a plot that were not stalk lodged. These designators will follow the descriptors to denote how the values are to be interpreted.
ABTSTK=ARTIFICIAL BRITTLE STALK. A count of the number of "snapped" plants per plot following machine snapping. A snapped plant has its stalk completely snapped at a node between the base of the plant and the node above the ear. Expressed as percent of plants that did not snap.
ALLELE. Any of one or more alternative forms of a genetic sequence. In a diploid cell or organism, the two alleles of a given sequence occupy corresponding loci on a pair of homologous chromosomes.
ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola). A 1 to 9 visual rating indicating the resistance to Anthracnose Stalk Rot. A higher score indicates a higher resistance.
BACKCROSSING. Process in which a breeder crosses a progeny line back to one of the parental genotypes one or more times.
BARPLT=BARREN PLANTS. The percent of plants per plot that was not barren (lack ears).
BREEDING. The genetic manipulation of living organisms.
BRTSTK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap.
CLDTST=COLD TEST. The percent of plants that germinate under cold test conditions.
CLN=CORN LETHAL NECROSIS. Synergistic interaction of maize chlorotic mottle virus (MCMV) in combination with either maize dwarf mosaic virus (MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV). A 1 to 9 visual rating indicating the resistance to Corn Lethal Necrosis. A higher score indicates a higher resistance.
COMRST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicating the resistance to Common Rust. A higher score indicates a higher resistance.
D/D=DRYDOWN. This represents the relative rate at which a hybrid will reach acceptable harvest moisture compared to other hybrids on a 1-9 rating scale. A high score indicates a hybrid that dries relatively fast while a low score indicates a hybrid that dries slowly.
DIPERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodia macrospora). A 1 to 9 visual rating indicating the resistance to Diplodia Ear Mold. A higher score indicates a higher resistance.
DIPROT=DIPLODIA STALK ROT SCORE. Score of stalk rot severity due to Diplodia (Diplodia maydis). Expressed as a 1 to 9 score with 9 being highly resistant.
DRPEAR=DROPPED EARS. A measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.
D/T=DROUGHT TOLERANCE. This represents a 1-9 rating for drought tolerance, and is based on data obtained under stress conditions. A high score indicates good drought tolerance and a low score indicates poor drought tolerance.
EARHT=EAR HEIGHT. The ear height is a measure from the ground to the highest placed developed ear node attachment and is measured in centimeters.
EARMLD=General Ear Mold. Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining the specific mold organism, and may not be predictive for a specific ear mold.
EARSZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.
EBTSTK=EARLY BRITTLE STALK. A count of the number of "snapped" plants per plot following severe winds when the corn plant is experiencing very rapid vegetative growth in the V5-V8 stage. Expressed as percent of plants that did not snap.
ECB1LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinia nubilalis). A 1 to 9 visual rating indicating the resistance to preflowering leaf feeding by first generation European Corn Borer. A higher score indicates a higher resistance.
ECB2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING (Ostrinia nubilalis). Average inches of tunneling per plant in the stalk.
ECB2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1 to 9 visual rating indicating post flowering degree of stalk breakage and other evidence of feeding by European Corn Borer, Second Generation. A higher score indicates a higher resistance.
ECBDPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Dropped ears due to European Corn Borer. Percentage of plants that did not drop ears under second generation corn borer infestation.
EGRWTH=EARLY GROWTH. This is a measure of the relative height and size of a corn seedling at the 2-4 leaf stage of growth. This is a visual rating (1 to 9), with 1 being weak or slow growth, 5 being average growth and 9 being strong growth. Taller plants, wider leaves, more green mass and darker color constitute higher score.
ELITE INBRED. An inbred that contributed desirable qualities when used to produce commercial hybrids. An elite inbred may also be used in further breeding.
ERTLDG=EARLY ROOT LODGING. Early root lodging is the percentage of plants that do not root lodge prior to or around anthesis; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.
ERTLPN=Early root lodging. An estimate of the percentage of plants that do not root lodge prior to or around anthesis; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be considered as root lodged.
ERTLSC=EARLY ROOT LODGING SCORE. Score for severity of plants that lean from a vertical axis at an approximate 30-degree angle or greater, which typically results from strong winds prior to or around flowering recorded within 2 weeks of a wind event. Expressed as a 1 to 9 score with 9 being no lodging.
ESTCNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on per plot basis for the inbred or hybrid.
EYESPT=Eye Spot (Kabatiella zeae or Aureobasidium zeae). A 1 to 9 visual rating indicating the resistance to Eye Spot. A higher score indicates a higher resistance.
FUSERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusarium subglutinans). A 1 to 9 visual rating indicating the resistance to Fusarium ear rot. A higher score indicates a higher resistance.
GDU=Growing Degree Units. Using the Barger Heat Unit Theory, which assumes that maize growth occurs in the temperature range 50.degree. F.-86.degree. F. and that temperatures outside this range slow down growth; the maximum daily heat unit accumulation is 36 and the minimum daily heat unit accumulation is 0. The seasonal accumulation of GDU is a major factor in determining maturity zones.
GDUSHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##
The highest maximum temperature used is 86.degree. F. and the lowest minimum temperature used is 50.degree. F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.
GDUSLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.
GENOTYPE. Refers to the genetic constitution of a cell or organism.
GIBERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberelia zeae). A 1 to 9 visual rating indicating the resistance to Gibberella Ear Rot. A higher score indicates a higher resistance.
GIBROT=GIBBERELLA STALK ROT SCORE. Score of stalk rot severity due to Gibberella (Gibberella zeae). Expressed as a 1 to 9 score with 9 being highly resistant.
GLFSPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1 to 9 visual rating indicating the resistance to Gray Leaf Spot. A higher score indicates a higher resistance.
GOSWLT=Goss' Wilt (Corynebacterium nebraskense). A 1 to 9 visual rating indicating the resistance to Goss' Wilt. A higher score indicates a higher resistance.
GRNAPP=GRAIN APPEARANCE. This is a 1 to 9 rating for the general appearance of the shelled grain as it is harvested based on such factors as the color of harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.
H/POP=YIELD AT HIGH DENSITY. Yield ability at relatively high plant densities on 1-9 relative rating system with a higher number indicating the hybrid responds well to high plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to increased plant density.
HCBLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporium carbonum). A 1 to 9 visual rating indicating the resistance to Helminthosporium infection. A higher score indicates a higher resistance.
HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates the percentage of plants not infected.
HSKCVR=HUSK COVER. A 1 to 9 score based on performance relative to key checks, with a score of 1 indicating very short husks, tip of ear and kernels showing; 5 is intermediate coverage of the ear under most conditions, sometimes with thin husk; and a 9 has husks extending and closed beyond the tip of the ear. Scoring can best be done near physiological maturity stage or any time during dry down until harvested.
INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acre assuming drying costs of two cents per point above 15.5 percent harvest moisture and current market price per bushel.
INCOME/ACRE. Income advantage of hybrid to be patented over other hybrid on per acre basis.
INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1 over variety #2.
KSZDCD=KERNEL SIZE DISCARD. The percent of discard seed; calculated as the sum of discarded tip kernels and extra large kernels.
LINKAGE. Refers to a phenomenon wherein alleles on the same chromosome tend to segregate together more often than expected by chance if their transmission was independent.
LINKAGE DISEQUILIBRIUM. Refers to a phenomenon wherein alleles tend to remain together in linkage groups when segregating from parents to offspring, with a greater frequency than expected from their individual frequencies.
L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plant densities on a 1-9 relative system with a higher number indicating the hybrid responds well to low plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to low plant density.
LRTLDG=LATE ROOT LODGING. Late root lodging is the percentage of plants that do not root lodge after anthesis through harvest; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.
LRTLPN=LATE ROOT LODGING. Late root lodging is an estimate of the percentage of plants that do not root lodge after anthesis through harvest; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be considered as root lodged.
LRTLSC=LATE ROOT LODGING SCORE. Score for severity of plants that lean from a vertical axis at an approximate 30-degree angle or greater which typically results from strong winds after flowering. Recorded prior to harvest when a root-lodging event has occurred. This lodging results in plants that are leaned or "lodged" over at the base of the plant and do not straighten or "goose-neck" back to a vertical position. Expressed as a 1 to 9 score with 9 being no lodging.
MDMCPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus and MCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating the resistance to Maize Dwarf Mosaic Complex. A higher score indicates a higher resistance.
MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.
MSTADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 over variety #2 as calculated by: MOISTURE of variety #2-MOISTURE of variety #1=MOISTURE ADVANTAGE of variety #1.
NLFBLT=Northern Leaf Blight (Helminthosporium turcicum or Exserohilum turcicum). A 1 to 9 visual rating indicating the resistance to Northern Leaf Blight. A higher score indicates a higher resistance.
OILT=GRAIN OIL. Absolute value of oil content of the kernel as predicted by Near-infrared Transmittance and expressed as a percent of dry matter.
PEDIGREE DISTANCE. Relationship among generations based on their ancestral links as evidenced in pedigrees. May be measured by the distance of the pedigree from a given starting point in the ancestry.
PLTHT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in centimeters.
POLSC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount of pollen shed. The higher the score the more pollen shed.
POLWT=POLLEN WEIGHT. This is calculated by dry weight of tassels collected as shedding commences minus dry weight from similar tassels harvested after shedding is complete.
POP K/A=PLANT POPULATIONS. Measured as 1000s per acre.
POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage of variety #1 over variety #2 as calculated by PLANT POPULATION of variety #2-PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety #1.
PRM=PREDICTED RELATIVE MATURITY. This trait, predicted relative maturity, is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is also referred to as the Comparative Relative Maturity Rating System that is similar to the Minnesota Relative Maturity Rating System.
PRMSHD=A relative measure of the growing degree units (GDU) required to reach 50% pollen shed. Relative values are predicted values from the linear regression of observed GDU's on relative maturity of commercial checks.
PROT=GRAIN PROTEIN. Absolute value of protein content of the kernel as predicted by Near-Infrared Transmittance and expressed as a percent of dry matter.
RTLDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.
RTLADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1 over variety #2.
SCTGRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.
SDGVGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.
SEL IND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A maize breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.
SLFBLT=SOUTHERN LEAF BLIGHT (Helminthosporium maydis or Bipolaris maydis). A 1 to 9 visual rating indicating the resistance to Southern Leaf Blight. A higher score indicates a higher resistance.
SOURST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual rating indicating the resistance to Southern Rust. A higher score indicates a higher resistance.
STAGRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.
STDADV=STALK STANDING ADVANTAGE. The advantage of variety #1 over variety #2 for the trait STK CNT.
STKCNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.
STKLDG=STALK LODGING REGULAR. This is the percentage of plants that did not stalk lodge (stalk breakage) at regular harvest (when grain moisture is between about 20 and 30%) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.
STKLDL=LATE STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) at or around late season harvest (when grain moisture is between about 15 and 18%) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.
STKLDS=STALK LODGING SCORE. A plant is considered as stalk lodged if the stalk is broken or crimped between the ear and the ground. This can be caused by any or a combination of the following: strong winds late in the season, disease pressure within the stalks, ECB damage or genetically weak stalks. This trait should be taken just prior to or at harvest. Expressed on a 1 to 9 scale with 9 being no lodging.
STLPCN=STALK LODGING REGULAR. This is an estimate of the percentage of plants that did not stalk lodge (stalk breakage) at regular harvest (when grain moisture is between about 20 and 30%) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.
STRT=GRAIN STARCH. Absolute value of starch content of the kernel as predicted by Near-infrared Transmittance and expressed as a percent of dry matter.
STWWLT=Stewart's Wilt (Erwinia stewartii). A 1 to 9 visual rating indicating the resistance to Stewart's Wilt. A higher score indicates a higher resistance.
TASBLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at the time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.
TASSZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.
TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.
TEXEAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).
TILLER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data are given as a percentage of tillers: number of tillers per plot divided by number of plants per plot.
TSTWT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grain in pounds for a given volume (bushel).
TSWADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety #1 over variety #2.
WIN M %=PERCENT MOISTURE WINS.
WIN Y %=PERCENT YIELD WINS.
YIELD BU/A=YIELD (BUSHELS/ACRE). Yield of the grain at harvest in bushels per acre adjusted to 15% moisture.
YLDADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety #2 as calculated by: YIELD of variety #1-YIELD variety #2=yield advantage of variety #1.
YLDSC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.
Definitions for Area of Adaptability
When referring to area of adaptability, such term is used to describe the location with the environmental conditions that would be well suited for this maize line. Area of adaptability is based on a number of factors, for example: days to maturity, insect resistance, disease resistance, and drought resistance. Area of adaptability does not indicate that the maize line will grow in every location within the area of adaptability or that it will not grow outside the area. Central Corn Belt: Iowa, Illinois, Indiana Drylands: non-irrigated areas of North Dakota, South Dakota, Nebraska, Kansas, Colorado and Oklahoma Eastern U.S.: Ohio, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia North central U.S.: Minnesota and Wisconsin Northeast: Michigan, New York, Vermont, and Ontario and Quebec Canada Northwest U.S.: North Dakota, South Dakota, Wyoming, Washington, Oregon, Montana, Utah, and Idaho South central U.S.: Missouri, Tennessee, Kentucky, and Arkansas Southeast U.S.: North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, and Louisiana Southwest U.S.: Texas, Oklahoma, New Mexico, and Arizona Western U.S.: Nebraska, Kansas, Colorado, and California Maritime Europe: France, Germany, Belgium and Austria
DETAILED DESCRIPTION OF THE INVENTION
Inbred maize lines are typically developed for use in the production of hybrid maize lines. Inbred maize lines need to be highly homogeneous, substantially homozygous and reproducible to be useful as parents of commercial hybrids. There are many analytical methods available to determine the homozygotic stability and the identity of these inbred lines.
The oldest and most traditional method of analysis is the observation of phenotypic traits. The data is usually collected in field experiments over the life of the maize plants to be examined. Phenotypic characteristics most often observed are for traits associated with plant morphology, ear and kernel morphology, insect and disease resistance, maturity, and yield.
In addition to phenotypic observations, the genotype of a plant can also be examined. A plant's genotype can be used to identify plants of the same variety or a related variety. For example, the genotype can be used to determine the pedigree of a plant. There are many laboratory-based techniques available for the analysis, comparison and characterization of plant genotype; among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs) which are also referred to as Microsatellites, and Single Nucleotide Polymorphisms (SNPs).
Isozyme Electrophoresis and RFLPs as discussed in Lee, M., "Inbred Lines of Maize and Their Molecular Markers," The Maize Handbook, (Springer-Verlag, New York, Inc. 1994, at 423-432) incorporated herein by reference, have been widely used to determine genetic composition. Isozyme Electrophoresis has a relatively low number of available markers and a low number of allelic variants among maize inbreds. RFLPs allow more discrimination because they have a higher degree of allelic variation in maize and a larger number of markers can be found. Both of these methods have been eclipsed by SSRs as discussed in Smith et al., "An evaluation of the utility of SSR loci as molecular markers in maize (Zea mays L.): comparisons with data from RFLPs and pedigree", Theoretical and Applied Genetics (1997) vol. 95 at 163-173 and by Pejic et al., "Comparative analysis of genetic similarity among maize inbreds detected by RFLPs, RAPDs, SSRs, and AFLPs," Theoretical and Applied Genetics (1998) at 1248-1255 incorporated herein by reference. SSR technology is more efficient and practical to use than RFLPs; more marker loci can be routinely used and more alleles per marker locus can be found using SSRs in comparison to RFLPs. Single Nucleotide Polymorphisms may also be used to identify the unique genetic composition of the invention and progeny lines retaining that unique genetic composition. Various molecular marker techniques may be used in combination to enhance overall resolution.
Maize DNA molecular marker linkage maps have been rapidly constructed and widely implemented in genetic studies. One such study is described in Boppenmaier, et al., "Comparisons among strains of inbreds for RFLPs", Maize Genetics Cooperative Newsletter, 65:1991, pg. 90, is incorporated herein by reference.
Inbred maize line PH4CV is a yellow, dent maize inbred that is well suited to be used as either the female or male in production of the first generation F1 maize hybrids. Inbred maize line PH4CV is best adapted to the Central Corn Belt, Eastern, Southcentral, and Southeast areas of the United States and can be used to produce hybrids with approximately a 113 maturity based on the Comparative Relative Maturity Rating System for harvest moisture of grain. Inbred maize line PH4CV demonstrates good female yield and good Southern Corn Leaf Blight, Stewarts Bacterial Leaf Blight and Gray Leaf Spot tolerance as an inbred per se. Inbred maize line PH4CV also has above average tolerance to Diplodia, Fusarium, and Gibberella ear rots as an inbred per se. In hybrid combination, inbred PH4CV demonstrates high grain yield, good foliar disease tolerance, and short ear and plant height.
The inbred has shown uniformity and stability within the limits of environmental influence for all the traits as described in the Variety Description Information (Table 1) that follows. The inbred has been self-pollinated and ear-rowed a sufficient number of generations with careful attention paid to uniformity of plant type to ensure the homozygosity and phenotypic stability necessary to use in commercial production. The line has been increased both by hand and in isolated fields with continued observation for uniformity. No variant traits have been observed or are expected in PH4CV.
Inbred maize line PH4CV, being substantially homozygous, can be reproduced by planting seeds of the line, growing the resulting maize plants under self-pollinating or sib-pollinating conditions with adequate isolation, and harvesting the resulting seed using techniques familiar to the agricultural arts.
TABLE 1 VARIETY DESCRIPTION INFORMATION VARIETY = PH4CV 1. TYPE: 2 1 = Sweet 2 = Dent 3 = Flint 4 = Flour 5 = Pop 6 = Ornamental 2. MATURITY: DAYS HEAT UNITS 074 1,439.3 From emergence to 50% of plants in silk 074 1,451.8 From emergence to 50% of plants in pollen 002 0,067.7 From 10% to 90% pollen shed From 50% silk to harvest at 25% moisture Standard Sample 3. PLANT: Deviation Size 0,221.8 cm Plant Height (to tassel tip) 12.41 45 0,078.3 cm Ear Height (to base of top ear 7.84 45 node) 0,015.2 cm Length of Top Ear Internode 1.07 45 0.0 Average Number of Tillers 0.03 9 0.9 Average Number of Ears per Stalk 0.11 9 3.0 Anthocyanin of Brace Roots: 1 = Absent 2 = Faint 3 = Moderate 4 = Dark 5 = Very Dark Standard Sample 4. LEAF: Deviation Size 010.5 cm Width of Ear Node Leaf 0.75 45 077.3 cm Length of Ear Node Leaf 3.17 45 07.1 Number of leaves above top ear 0.52 45 15.4 Degrees Leaf Angle (measure from 4.68 45 2nd leaf above ear at anthesis to stalk above leaf) 03 Leaf Color Dark Green ~undefinedMC) 7.5GY34 1.2 Leaf Sheath Pubescence (Rate on scale from 1 = none to 9 = like peach fuzz) Marginal Waves (Rate on scale from 1 = none to 9 = many) Longitudinal Creases (Rate on scale from 1 = none to 9 = many) Standard Sample 5. TASSEL: Deviation Size 04.7 Number of Primary Lateral 1.63 45 Branches 015.5 Branch Angle from Central Spike 6.20 45 50.4 cm Tassel Length (from top leaf collar 3.87 45 to tassel tip) 5.2 Pollen Shed (rate on scale from 0 = male sterile to 9 = heavy shed) 07 Anther Color Yellow ~undefinedMC) 10Y96 01 Glume Color Light Green ~undefinedMC) 5GY56 1.0 Bar Glumes (Glume Bands): 1 = Absent 2 = Present 17 cm Peduncle Length (cm. from top leaf to basal branches) 6a. EAR (Unhusked Data): 11 Silk Color (3 days after emergence) Pink ~undefinedMC) 2.5R58 1 Fresh Husk Color (25 days after 50% Light Green ~undefinedMC) 5GY56 21 Dry Husk Color (65 days after 50% silking) Buff ~undefinedMC) 2.5Y92 3 Position of Ear at Dry Husk Stage: 1 = Upright 2 = Horizontal 3 = Pendant 5 Husk Tightness (Rate of Scale from 1 = very loose to 9 = very tight) 2 Husk Extension (at harvest): 1 = Short (ears exposed) 2 = Medium (<8 cm) 3 = Long (8-10 cm beyond ear tip) 4 = Very Long (>10 cm) Standard Sample 6b. EAR (Husked Ear Data): Deviation Size 15 cm Ear Length 0.88 45 42 mm Ear Diameter at mid-point 2.01 45 111 gm Ear Weight 23.87
SHINEWSZ wrote:
专家不是都有定论了嘛，跟转基因没关系。
最近微博转发地很火的一条就是：“。。。。有毒小龙虾跟洗虾粉没关系、不良反应跟疫苗没关系、专家老婆怀孕了——跟专家没关系。”
这个评论太帅了！
我觉得这些基因本来就存在于自然界，只不过我们把它加入到作物里面改变其某些功能。吃进去后都会消化成核苷酸，我不认为转基因食品会给人体健康带来危险。
主要的风险是转基因作物可能会破坏天然的生态链，给自然生态带来影响。
主要的风险是转基因作物可能会破坏天然的生态链，给自然生态带来影响。
一面是以温某人为首的和谐世界派力推转基因食品及主粮，一面是上海世搏会严查转基因食品，唯恐洋大人食用引起友邦惊诧愤怒。转基因食品在国外大量动物试验证实其非常不安全，在国内未经任何论证与试验，却即有大批洋奴精英赌咒发誓保证三百年不出问题，联系到中国是世界上唯一一个批准转基因主粮商品化种植推广的国家，且是由温某人挂帅坚定不移推进的，可以肯定，这里有一个巨大的阴谋，这个阴谋就是亡我中华民族。
只要国民人人觉醒，人人积极抵制，不给其任何商机，则转基因不过是南柯一梦，成不了气候。但绝不能小看ZF强制推行转基因主粮的险恶用心，从一开始就绝不给转基因食品任何生存之地，否则，一旦气候已成，除了转基因，没有其它东西可吃，则只有饮鸩食毒了。
若干年后，或许我们会发现，无毒无害的食品就如当今的别墅一样，不是任何人都消受得起的了。
只要国民人人觉醒，人人积极抵制，不给其任何商机，则转基因不过是南柯一梦，成不了气候。但绝不能小看ZF强制推行转基因主粮的险恶用心，从一开始就绝不给转基因食品任何生存之地，否则，一旦气候已成，除了转基因，没有其它东西可吃，则只有饮鸩食毒了。
若干年后，或许我们会发现，无毒无害的食品就如当今的别墅一样，不是任何人都消受得起的了。
我还是觉得转基因作物可以给人体健康带来危险.
玉米转基因后,不清楚玉米粒的成分发生了什么改变,比如说一些蛋白质,一些脂类,还有微量元素类,可能某种物质本来对身体无害,改变之后身体不适应它,日积月累,常吃的话,就有害了.
玉米转基因后,不清楚玉米粒的成分发生了什么改变,比如说一些蛋白质,一些脂类,还有微量元素类,可能某种物质本来对身体无害,改变之后身体不适应它,日积月累,常吃的话,就有害了.
美国居民大量食用转基因食品，谁有该方面的证据证明？转基因食品到底是否危害健康，国家怎样对待转基因食品？百姓又如何看待转基因食品？不知不觉都已经在食用转基因食品，一点知情权都没有，更别说选择权!悲剧！
据说连非洲都拒绝接受转基因粮食，大家百度一下吧
或许有一天人的骨头像玉米杆一样脆就恐怖了
或许有一天人的骨头像玉米杆一样脆就恐怖了
不要盲信，不要跟风
我相信，美国这个转基因玉米被FDA批准之前，肯定没有做过像中国这样大规模种植并且喂养动物的实验。
我们的老百姓也算作为向人家付费的实验对象了。
而且，既然实验结果都明摆着放在那里，
一帮专家竟然“掩耳盗铃”，
不为自己积贫积弱的衣食父母说话。
或者以坦诚的心态和语言，接受这个事实。
然后以此前车之鉴，做细致的研究。
揭示真相。
而不是像很多地方政府一样，一出事情，第一反应就是“捂住”。
我们的老百姓也算作为向人家付费的实验对象了。
而且，既然实验结果都明摆着放在那里，
一帮专家竟然“掩耳盗铃”，
不为自己积贫积弱的衣食父母说话。
或者以坦诚的心态和语言，接受这个事实。
然后以此前车之鉴，做细致的研究。
揭示真相。
而不是像很多地方政府一样，一出事情，第一反应就是“捂住”。
转基因食物是否有安全隐患是个有争议的问题，但是转基因作物在美国的大量种植和消费是不争的事实。相关的情况可以参考下面的wikipedia网页：
http://en.wikipedia.org/wiki/Genetically_modified_food
美国93％的Soybeans，86％的Corn，93％的Cotton，80％Hawaiian papaya，93％的Rapeseed都是转基因作物。美国人似乎不太在意这个事情，我曾问过美国同事为什么美国的玉米都这么甜（有的可以直接拨了皮生吃），她说因为我们的玉米都是转基因的。有趣的是曾听到美国人抱怨鸡肉有玉米的味道，因为鸡主要是吃玉米长大的，而鸡肉都是用玉米油炸的。
关注Science的同学应该注意到最近Nature的一篇文章，美国的转基因三文鱼有望很快被FDA批准（连接 http://www.nature.com/news/2010/100914/full/467259a.html
但是对这个问题欧洲人有皆然不同的观点，他们对转基因作物的看法基本是负面的。
http://en.wikipedia.org/wiki/Genetically_modified_food
美国93％的Soybeans，86％的Corn，93％的Cotton，80％Hawaiian papaya，93％的Rapeseed都是转基因作物。美国人似乎不太在意这个事情，我曾问过美国同事为什么美国的玉米都这么甜（有的可以直接拨了皮生吃），她说因为我们的玉米都是转基因的。有趣的是曾听到美国人抱怨鸡肉有玉米的味道，因为鸡主要是吃玉米长大的，而鸡肉都是用玉米油炸的。
关注Science的同学应该注意到最近Nature的一篇文章，美国的转基因三文鱼有望很快被FDA批准（连接 http://www.nature.com/news/2010/100914/full/467259a.html
但是对这个问题欧洲人有皆然不同的观点，他们对转基因作物的看法基本是负面的。
bingdongbaihe wrote:
美国居民大量食用转基因食品，谁有该方面的证据证明？转基因食品到底是否危害健康，国家怎样对待转基因食品？百姓又如何看待转基因食品？不知不觉都已经在食用转基因食品，一点知情权都没有，更别说选择权!悲剧！
转基因水稻研究第一人：“功臣”还是“汉奸”
来源：财新网 2010年03月29日
在很多人看来，他是中国研究和推广转基因技术的功臣；与此同时，在另一部分人眼中，他又是出卖国家和民族利益的“大汉奸”。
他就是走在中国转基因水稻研究前列的华中农业大学教授张启发。
2009年8月，张启发研究团队的两个转基因水稻品种，率先获得农业部颁发的生产应用安全证书，在转基因水稻商业化的道路上迈出了关键一步。
走到这一步，张启发历尽艰难。
绿色超级稻梦想
张启发是湖北公安人。1985年，张启发在美国加州大学戴维斯分校获得博士学位，其导师是美国科学院院士、担任过美国遗传学会主席的罗伯特?阿拉德（Robert Allard）。
次年，张启发回到华中农业大学。《湖北日报》2004年的报道说，时任华中农业大学校长的孙济中教授拍板，在张启发回国时投入10万元启动资金。
渐渐地，张启发不缺研究经费了。根据前述报道，张启发主持的国家重点实验室所争取的科研经费，一度占到整个华中农业大学的三分之一。
张启发赶上了中国大力发展转基因生物技术的好时候。中国政府历年来已在转基因生物育种方面投入数以亿计的研究经费。2008年启动的转基因生物新品种培育重大科技专项，投入更是将高达200多亿元。很多科学家认为，转基因生物育种可以造福大众，对于中国的粮食安全也具有重要意义。张启发的同事、华中农业大学林拥军教授举例说，近年来中国多个地方连续干旱，如果寻找到抗旱基因，“那是很了不得的，还有可能得诺贝尔奖。”
在转基因抗虫水稻研究的基础上，张启发不失时机地提出“绿色超级稻”的梦想：转基因技术今后不仅帮助实现水稻高产，还能同时做到“少打农药，少施化肥，抗旱节水，优质高产”，最大程度地减少对生态的影响。
1999年，年仅45岁的张启发当选为中国科学院院士。也是在这一年，张启发团队研究出转基因抗虫水稻，开始瞄准产业化。
2004年，张启发团队向农业部申请转基因抗虫水稻的安全证书，未获通过。当时，绿色和平已经在中国发起反对转基因的运动，媒体上也陆续出现对转基因水稻安全性的质疑。
第二年，研究团队再次提出申请，仍然未获通过。有专家提出，华中农业大学是当事人，不应该自己来做或自己找人来做评价试验。于是，农业部组织第三方进行试验。
申请屡屡受挫，外界很难体会张启发的心情。2007年，一项荣誉或许多少给他带来了安慰。这一年，张启发与袁隆平一起入选美国科学院外籍院士。
到2008年年底，第三方试验完成以后，张启发团队再次提出申请。这一次，农业部农业转基因生物安全委员会没有提出更多质疑。2009年8月，他们的申请正式获得批准。
国内其他的转基因水稻研究团队，至今仍在排队等待安全证书的审批。张启发的研究团队拔得了头筹。
“给你涂上黑油漆”
张启发等来了渴盼多年的安全证书，却也换来一顶“大汉奸”的帽子。
今年2月，在北京的一个研讨会上，当张启发提到中国科学院农业政策研究中心黄季焜博士是“大汉奸”时，与会者不由得会心一笑。因为位列几个“大汉奸”之首的，正是张启发本人，其“罪状”是与美国孟山都这个全球最大的转基因农产品公司有过合作。
与国外公司进行合作，对研究人员来说是再正常不过的事情。但有网民将他们对转基因技术的恐惧和不满，宣泄到张启发和黄季焜这几位从事转基因技术或者是政策研究的科学家身上。
与“大汉奸”这顶帽子相比，张启发更担心的是，各种关于转基因的不实言论给公众带来误解，并且影响到决策者。他曾经感叹说：“给你涂上黑油漆，你就洗不干净了。”
一些媒体和公众对张启发等科学家在转基因产业化进程中是否存在利益诉求提出质疑。张启发则和同事们提出了将转基因抗虫水稻品种公益化的设想。在张启发门下攻读过博士的浙江大学凃巨民教授说：“如果国家同意，这个产品完全可以公益化。”
反对转基因水稻的声音，让张启发深陷舆论的漩涡。如何与公众更好地沟通，也是他需要直面的难题之一。
来源：财新网 2010年03月29日
在很多人看来，他是中国研究和推广转基因技术的功臣；与此同时，在另一部分人眼中，他又是出卖国家和民族利益的“大汉奸”。
他就是走在中国转基因水稻研究前列的华中农业大学教授张启发。
2009年8月，张启发研究团队的两个转基因水稻品种，率先获得农业部颁发的生产应用安全证书，在转基因水稻商业化的道路上迈出了关键一步。
走到这一步，张启发历尽艰难。
绿色超级稻梦想
张启发是湖北公安人。1985年，张启发在美国加州大学戴维斯分校获得博士学位，其导师是美国科学院院士、担任过美国遗传学会主席的罗伯特?阿拉德（Robert Allard）。
次年，张启发回到华中农业大学。《湖北日报》2004年的报道说，时任华中农业大学校长的孙济中教授拍板，在张启发回国时投入10万元启动资金。
渐渐地，张启发不缺研究经费了。根据前述报道，张启发主持的国家重点实验室所争取的科研经费，一度占到整个华中农业大学的三分之一。
张启发赶上了中国大力发展转基因生物技术的好时候。中国政府历年来已在转基因生物育种方面投入数以亿计的研究经费。2008年启动的转基因生物新品种培育重大科技专项，投入更是将高达200多亿元。很多科学家认为，转基因生物育种可以造福大众，对于中国的粮食安全也具有重要意义。张启发的同事、华中农业大学林拥军教授举例说，近年来中国多个地方连续干旱，如果寻找到抗旱基因，“那是很了不得的，还有可能得诺贝尔奖。”
在转基因抗虫水稻研究的基础上，张启发不失时机地提出“绿色超级稻”的梦想：转基因技术今后不仅帮助实现水稻高产，还能同时做到“少打农药，少施化肥，抗旱节水，优质高产”，最大程度地减少对生态的影响。
1999年，年仅45岁的张启发当选为中国科学院院士。也是在这一年，张启发团队研究出转基因抗虫水稻，开始瞄准产业化。
2004年，张启发团队向农业部申请转基因抗虫水稻的安全证书，未获通过。当时，绿色和平已经在中国发起反对转基因的运动，媒体上也陆续出现对转基因水稻安全性的质疑。
第二年，研究团队再次提出申请，仍然未获通过。有专家提出，华中农业大学是当事人，不应该自己来做或自己找人来做评价试验。于是，农业部组织第三方进行试验。
申请屡屡受挫，外界很难体会张启发的心情。2007年，一项荣誉或许多少给他带来了安慰。这一年，张启发与袁隆平一起入选美国科学院外籍院士。
到2008年年底，第三方试验完成以后，张启发团队再次提出申请。这一次，农业部农业转基因生物安全委员会没有提出更多质疑。2009年8月，他们的申请正式获得批准。
国内其他的转基因水稻研究团队，至今仍在排队等待安全证书的审批。张启发的研究团队拔得了头筹。
“给你涂上黑油漆”
张启发等来了渴盼多年的安全证书，却也换来一顶“大汉奸”的帽子。
今年2月，在北京的一个研讨会上，当张启发提到中国科学院农业政策研究中心黄季焜博士是“大汉奸”时，与会者不由得会心一笑。因为位列几个“大汉奸”之首的，正是张启发本人，其“罪状”是与美国孟山都这个全球最大的转基因农产品公司有过合作。
与国外公司进行合作，对研究人员来说是再正常不过的事情。但有网民将他们对转基因技术的恐惧和不满，宣泄到张启发和黄季焜这几位从事转基因技术或者是政策研究的科学家身上。
与“大汉奸”这顶帽子相比，张启发更担心的是，各种关于转基因的不实言论给公众带来误解，并且影响到决策者。他曾经感叹说：“给你涂上黑油漆，你就洗不干净了。”
一些媒体和公众对张启发等科学家在转基因产业化进程中是否存在利益诉求提出质疑。张启发则和同事们提出了将转基因抗虫水稻品种公益化的设想。在张启发门下攻读过博士的浙江大学凃巨民教授说：“如果国家同意，这个产品完全可以公益化。”
反对转基因水稻的声音，让张启发深陷舆论的漩涡。如何与公众更好地沟通，也是他需要直面的难题之一。
楼上貌似很为张教授鸣不平，可是我们不得不提防。
我想说一句，如果给你指路的人就拿你当剑使，给你指了条错误的路，即使在这条路上受了再多的挫折和委屈，都不值得抱怨。
从小，我们就被教育要遵从师长的教导，老师让干嘛就干嘛，不知道张教授的研究路线是自己的兴趣还是老师指引的呢
又说，中国需要抗旱水稻，那为什么首先研究的和推广的是抗虫水稻？
没事，咱们讨论一下呗。
我想说一句，如果给你指路的人就拿你当剑使，给你指了条错误的路，即使在这条路上受了再多的挫折和委屈，都不值得抱怨。
从小，我们就被教育要遵从师长的教导，老师让干嘛就干嘛，不知道张教授的研究路线是自己的兴趣还是老师指引的呢
又说，中国需要抗旱水稻，那为什么首先研究的和推广的是抗虫水稻？
没事，咱们讨论一下呗。
转基因食品危害大
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