| Rice is not only one of major cereal crops for human being but also an important model species for plant research. Development of transformation technique has shown great impacts on both rice breeding practice and functional genomics study. This technique has, however, been only succeeded in some of japonica rice but not in indica rice. Information about the transformation efficiency of elite rice varieties is, therefor, useful to further improve the development of rice transgenic breeding. In this study, a total of21elite rice varieties,16indica and5japonica, were selected and investigated for the regeneration and transformation frequencies generated from tissue culture experiments. Regenaration experiments were initially conducted from the tissue culture of the mature embryos of all21varieties, and14varieties were then selected for gene transformation study.The results are as follows:1. Regeneration efficiency:(1) significantally different callus induction rates (C1R,%), ranged between25%and70%, were observed for in different rice varieties;(2) different morphological characteristics and regeneration abilities of the calli after continiously sub-culture were found for different varieties and (3) different scores of the average number of regenerated shoots per callus (NRS) and regeneration rate (RR), were recorded for the different day-olds (15d,25d and35d) calli’s culture on two different regeneration media NBm and DL3,respectively. It was found that regeneration ability was associated with the age of calli and DL3differentiation medium was better for indica rice while NBm better for japonica rice.2. Transformation efficiency:Agrobactium-midiated transformation of Bt gene was performed on14varieties and transgenic plants were obtained from8varieties after PCR identification of the target gene. Different frequencies of transformation in different rice varieties were ranged from0to25%and corresponded with different regeneration frequencies of the varieties. |
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