分子标记辅助选择改良Ⅱ-32B的外观品质

Molecular Marker-assisted Selection for Improving Appearance Quality of Ⅱ-32B

本研究以优质稻品种佳辐占为供体亲本与轮回亲本Ⅱ-32B进行连续回交，采用选择回交导入法结合分子标记辅助选择技术和农艺性状选择，将粒长主效基因GS3及其他外观品质性状基因导入Ⅱ-32B中，获得4个外观品质得到明显改善的Ⅱ-32B改良株系。Ⅱ-32B改良株系的谷粒明显变得细长，粒长由原来的8．04mm增加到8．99mm，粒宽由3．02mm降至2．85mm，长宽比由原来的2．67提高到3．16。此外，垩白率和垩白度极显著降低，分别由原来的55．6％和14．3％降低至23．9％和4．6％。除千粒重极显著增加外，抽穗期、株高、有效穗、穗长、结实率等5个主要农艺性状差异不显著。通过遗传背景分析，4个改良株系的遗传背景回复率为90．7％-96．3％，其中GL2株系分别在第5和第6染色体存在一个位点未回复外，其他位点均回复，回复率达到96．3％。结果表明，采用分子标记辅助选择与田间表型选择相结合可较快速地改良杂交稻亲本的外观品质。

Jiafuzhan as donor parent with high quality was selected to backcross successively with 11-32B as rec- urrent parent. The major QTL for grain length GS3 and the other genes of appearance quality in Jiafuzhan were transferred to 11 -32B to obtain four introgression lines by selecting successive backcrossing combined with molecular marker-assisted and phenotypic selection. Appearance quality analysis showed that grain shape of these introgression lines were significantly slender than I1-32B. Their grain length and length to width ratio was raised from 8.04 mm of 11 -32B to 8.99 mm and from 2.67 to 3.16 respectively, while the grain width was reduced to 2.85 mm from 3.02 mm. Furthermore, chalkiness ratio and chalkiness degree were significantly decreased from 55.6% and 14.3% to 23.9% and 4.6%, respectively. Agronomic traits comparative analysis showed the 1 000-grain weight performed significant differences whereas the other five main agronomic traits were not significant differences between the four introgression lines and lI -32B. Genetic background analysis revealed these introg- ression lines＇ genetic background recovering ratio ranged from 90.7% to 96.3%. Of these introgression lines, the genetic background recovering ratio of GL2 was highest at 96.3% and all chromosomes were recovered except chromosome 5 and 6 with only one locus respectively. The results indicated the appearance quality for hybrid parents could be improved much faster through combining marker-assisted selection with phenotype selection compared to conventional breeding.