Xieyou 57,an elite indica hybrid between the male-sterile line Xieqingzao A and the restorer line 057,owns high yield and wide adaptability.The high amylose content(AC) in the endosperm of both parents relatively results in poor cooking and eating quality of the hybrid.057(the restorer line,designated as 057(GG)) and XieqingzaoA(the male-sterile line,designated as XA(GG)) on Wx gene was improved.The AC eating quality and granule-bound starch synthase(GBSS) activity of all the four combinations were analyzed.The results revealed that the AC of the single parent improved hybrids,Xieqingzao A(GG) 057(TT) and Xieqingzao A(TT) 057(GG) were 19.9% and 19.3%,respectively.Both were lower than that of original Xieyou 57(GG,26.2%).Result indicated that the improved line of hybrid with homozygous TT-Wx-Xieqingzao A(TT)×057(TT),not only showed a decreased AC(12.5%),but also had better uniform AC for different seeds and good cooking and eating quality.The GBSS activity was tightly related to AC,and the three Wx genotype showed GGGTTT.

Xieyou 57, an elite hybrid rice with high grain yield and broad eco-adaptability, is widely planted in China. Its cooking and eating quality, however, is unsatisfactory due to high-amylose content (AC). In this research, a molecular marker-assisted selection method was used to breed for low-amylose content through the modification of the Wx genes in both parents of Xieyou 57. The quality of the parent and hybrid lines were then compared before and after modification. Amylose content of GT-type hybrids derived from crosses of Xieqingzao A(GG) × 057(TT) or Xieqingzao A(TT) × 057(GG), was reduced to about 19% from about 26% in the original hybrid Xieqingzao A(GG) × 057(GG). Wide variation in amylose contents, however, was observed in these GT-type hybrids. With further improvements in both parental lines, the TT type hybrid of Xieqingzao A(TT) × 057(TT) contained even lower amylose (12.5%) with good uniformity and exhibited much better cooking and eating quality than the original hybrid of Xieqingzao A(GG) × 057(GG). Meanwhile, yield potential was also improved by increasing panicle size and grain number of the male sterile line. These results demonstrated the success in significantly improving the cooking and eating quality of hybrid rice while maintaining the good agronomical attributes of the parent lines by using molecular marker-assisted breeding in combination with conventional agronomical selection.

为了培育出无筛选标记基因的转基因水稻,试验将loxp-hpt-loxp基因与Bt基因连锁在一起转化水稻方法,得到loxp-hpt-loxp-Bt转基因水稻植株,再与同质的带有cre基因的水稻杂交,以定向删除潮霉素抗性筛选标记。试验表明以水稻品种"皖粳97"为供试材料,将成熟胚来源的愈伤组织用根癌农杆菌EHA105/pCAMBIA1305.1感染后,筛选出抗性愈伤组织并获得再生植株。经PCR验证,得到20棵转基因水稻植株。

Xa23,Pi9 and Bt genes which possess wide resistance spectrum and high resistance level respectively to bacterial blight(BB),fungi blast,stemborers and leaffolders of rice were pyramided by molecular marker-assisted selection(MAS).Two homozygous lines HB1471 and HB1473 carrying the three resistant genes were obtained.Resistance identification showed that the pyramided lines HB1471 and HB1473 simultaneously possessed high resistance level to BB,blast and leaffolders(Cnaphalocrocis medialis).Compared with the Xa23 and Pi9 genes donor parent L10,the pyramided lines had the similar resistance spectrum and level to BB and blast.Meanwhile,they exhibited equivalent resistance to leaffolders with Bt donor parent MH63-Bt.The homozygous lines carrying Xa23,Pi9 and Bt genes should be very useful in rice breeding as donor of multiple resistance genes.

以转Bt基因的"克螟稻"为研究材料,通过使用特异的引物和荧光标记探针,以已知转基因成份含量的水稻样品为模板建立标准曲线,对转基因水稻的NOS和Bt外源基因进行了荧光定量检测分析.初步建立了转基因水稻定量检测的技术方法.

To lower the high amylose content of hybrid rice Xieyou 57(Xieqingzao A/057),Xieqingzao B(the maintainer line of Xieqingzao A)was used as recurrent parent and crossed with a donor parent with low amylose content.PCR-Acc Ⅰ molecular marker was applied during backcross to identify three Wx genotypes,i.e.GG,GT and TT.Then the genotypes,the amylose contents and agronomic traits of the four combinations,Xieqingzao B(GG)/057(GG),Xieqingzao B(GG)/057(TT),Xieqingzao B(TT)/057(GG),Xieqingzao B(TT)/057(TT)were detected,respectively.The amylose contents of the hybrids with heterozygous GT-Wx,i.e.Xieqingzao B(GG)/057(TT)and Xieqingzao B(TT)/057(GG)is 19.3% and 19.2% respectively,lower than that of Xieqingzao B(GG)/057(GG)(26.1%).The amylose contents of different seeds in the two hybrids with heterozygous GT-Wx differed greatly.The combination of Xieqingzao B(TT)/057(TT)with homozygous TT-Wx not only showed a decreased amylose content(12.5%)accompanied by increased gel consistency,but also had an improved uniformity in amylose contents among different seeds.