Binary Ti Plasmid Vectors

Living organisms have been continuously evolving by assimilating new genetic material from the environment. However, this progress is very slow and often limited to transfer of genetic materials among closely related species. Recent developments in molecular biology and gene transfer techniques enable researchers to move genetic information among a variety of living organisms. Gene transfer techniques for higher plants can be divided into two major methods: direct DNA transfer and Agrobacterium -mediated tumor inducing (Ti)-plasmid-vector methods. Direct DNA transfer methods have been used for the transformation of a wide variety of species, especially those plant species that are recalcitrant to transformation with Ti plasmid vectors. However, the direct DNA transfer method requires more manipulation and transformation efficiency is generally much lower compared to the Ti-plasmid-vector system. Furthermore, it appears that stability of introduced genes is lower when DNA was directly transferred. Therefore, Ti vectors are commonly used for transformation of most dicot plant species that are, in general, more readily transformed using Agrobacterium -mediated DNA delivery.