Reducing The Amylose Contents Of The Male Sterile Line 261S And Hybrid Rice "Min You Xiang Jing" By Introducing The Anti-waxy Gene

Rice is one of the most important food crops in the world and is a major food staple for half of the world's population. China is the first country which has successfully applied the rice heterosis utilization in the world. During the half century, great progresses have taken place in rice science and technology field in our country, which has tremendously contributed to the production of rice for our country and even the whole world. The paper reviewed the development on hybrid rice and the advances in rice character improvement. These essential improvements set up the basis on quality improvement and resistance for the breeding of hybrid rice and also bring forth a good prospect for the development of hybrid rice.Amylose content in rice endosperm is a major index affecting rice eating quality."Min you xiang jing"is a high yield, diseases resistance and fragrant japonica hybrid rice that derives from the hybrid combination 261S and W xiang 99075 by the breeding company of Min hang district, Shang hai City. It is also the only two-line hybrid rice applied in Shang hai City at present. Amylose contents in rice endosperm of"Min you xiang jing"is 18.5%, which can't meet the first-class quality standard of elite japonica rice issued by Chinese Ministry of Agriculture.In this study, we used the T1 seeds of the 6 transgenic lines as materials, which had been attained by introducing vectors p13AWY-1 and pCAMBIA1301 to the male sterile line via Agrobactium tumefaciens in our lab. 3 homozygotic transgenic lines were got by the PCR analysis of anti-waxy gene in transgenic plants in 3 generations. 4 T-DNA flanking sequences were amplified from T3 progeny, respectively in 4 transgenic lines, by TAIL-PCR. We analyzed the significance differences among the rate of setting seeds of 5 transgenic lines and wild type, among the rate of setting seeds of 5 transgenic lines and 261S by crossing with the restorer W xiang 99075. The results indicated that there were no significance differences among the rate of setting seeds by self crossing and crossing of 5 transgenic lines and wild type. It clarified that there was no adverse influence on the normal fertility of transgenic lines by introducing the anti-waxy gene. We also analyzed the significance differences among amylose contents of seeds in T4 and wild type, among amylose contents of seeds in F2 of transgenic lines by crossing with W xiang 99075. The results showed that the amylose contents of seeds in 4 T4 transgenic lines were reduced in the different levels. There were significance differences or highly significance differences among amylose contents of seeds in T4 and wild type. There were highly significance differences among amylose contents of seeds in F2 and the control. That is to say, we had improved 261S rice and Minyouxiangjing hybrid rice.In this study, we also had got dwarfing mutants that derived from the tissue culture in vitro. The dwarfing mutants had been stable by the observation in 2 generations. We respectively measured the plant height, the distance between panicle tip and leaf tip, the length of flag leaf and et al. There were highly significance differences among the dwarfing mutants, normal transgenic plants and wild type 261S by the statistic analysis. The dwarfing mutants were 10 cm shorter than the wild type in plant height. The average distance between panicle tip and leaf tip of 261S was 11 cm, but that of the dwarfing mutants was only 3 cm. In the experimental plots, we could observe the state of"ye shang he", which was the phenomenon of half of the panicles of the dwarfing mutants were over the leaves. It could be favorable for the pollens landing on the stigmas of pistils without obstructing by flag leaves in breeding by crossing, which might improve the rate of pollination and set more seeds. So the dwarfing mutants will set out a good prospect in breeding by crossing in the future.The selection of male parent of hybrid rice is expansive in two-line method breeding. Conventional varieties can be used as restorer line crossing with male-sterile line. So the female parent is more important than male parent in the study of two-line method breeding. Conventional breeding can be applied to characters improvement of two-line sterile line, but it is time consuming and is hard to maintain the natural characteristic of sterile line. In this study, we have achieved 261S transgenic lines reducing amylose contents in rice endosperm by gene engineering technology and dwarfing mutants of 261S by the issue culture in vitro. They will establish a profound basis for new combinations of two-line hybrid rice.