Callus Initiation, Maintenance, and Shoot Induction in Rice

Embryogenic suspension cultures provide the most widely employed source of totipotent cells for protoplast isolation in rice (Oryza sativa L.), since mesophyll-derived protoplasts of this important cereal rarely undergo sustained mitotic division leading to the production of tissues capable of plant regeneration. Cells from embryogenic suspensions provide an alternative to immature zygotic embryos for biolistic-mediated production of fertile transgenic rice plants (1 ) and are also amenable to transformation procedures employing agrobacteria (2 ). Currently, protocols are available for regenerating fertile plants from cell suspension-derived protoplasts of the three major subgroups of rice varieties, namely japonica (3 ), javanica (4 ) and indica (5 ) rices.