关键词: 水稻, 同源片段, bar基因, 叶绿体转化

Abstract: 【Objective】The aim of this study was to establish an expression system for foreign genes in rice chloroplast genome.【Method】By analyzing the published complete nucleotide sequence of rice chloroplast genome and its gene distribution pattern, the intergenic region of ndhF and trnl on chloroplast genome was selected as target for site-specific integration of PPT-resistant bar gene. Two fragments were cloned from rice chloroplast genome DNA by using PCR technique, which were suitable for homologous recombination in the genetic transformation of rice genome. A gene expression cassette was generated by fusing a modified 16S rRNA gene promoter to bar gene and using 3’ sequence of psbA gene as terminator. Based on this cassette and the cloned homologous fragments, the chloroplast-specific expression vector pRB was constructed. 【Result】Chloroplast transformation was carried out by biolistic bombardment of sterile rice calli with plasmid pRB. Subsequently, the regenerated plantlets, and seeds of progeny arising from reciprocal cross to the wild-type lines, were obtained. Molecular analysis on the transformed plants indicated that foreign gene bar has been integrated into rice chloroplast genome in a site-specific way. Genetic analysis with seeds of progeny revealed that bar gene expressed normally in rice chloroplast genome, and could be stably transmitted into next generation. 【Conclusion】Therefore, it was suggested that an efficient gene expression system in the rice chloroplast has been established by chloroplast transformation technique. The bar gene conferred not only selection pressure for the transformation of rice chloroplast genome, but PPT-resistant trait for rice plants as well.

Key words: Oryza sativa L., Homologous fragments, bar gene, Chloroplast transformation