Detection of QTLs for traits of agronomic importance and analysis of their stabilities using SSSLs in rice

Chinese. 单片段代换系（SSSL）是通过高代回交和分子标记辅助选择构建的，只含有来自供体亲本的一个染色体片段，遗传背景与受体亲本相同的品系。本研究的目的是利用SSSL检测不同环境条件下水稻重要性状的QTL。以32个SSSL为材料，随机区组试验设计，在2～4个季节中对水稻22个重要性状的QTL进行分析。共鉴定出59个QTL，分布于第1、2、3、4、6、7、8、10和11号染色体上。其中的18个QTL能够在2次以上重复检出，稳定性较好的QTL占检出QTL的30.5%，大多数农艺性状的QTL效应较小、稳定性较差。不同的性状，QTL稳定性不同，千粒重、粒长、谷粒长宽比、抽穗天数等性状的QTL较稳定。稳定性好的QTL，不仅具有较大的加性效应，而且受环境影响较小。利用单片段代换系可以有效地对水稻重要性状的QTL进行多年多季的稳定性分析。水稻大多数重要农艺性状QTL的不稳定性，反映了水稻生长发育过程的可塑性，可能是通过栽培措施使水稻品种获得高产优质的重要遗传基础。

English. Single segment substitution lines (SSSLs) each with only single chromosome segment from a donor under the same genetic background as the recipient were developed in rice by advanced backcrossing and molecular marker-assisted selection. Using the SSSLs, the QTLs for the traits of agronomic importance in rice were detected under different environmental conditions. Detection of the QTLs controlling 22 important traits in rice was done with 32 SSSLs by the randomized blocks design in 2-4 cropping seasons. 59 QTLs were detected and distributed on chromosomes 1, 2, 3, 4, 6, 7, 8, 10 and 11, of which 18 QTLs were detected two times or more. Only 30.5% of the QTLs were detected repeat in different cropping seasons. Most of the QTLs of agronomic importance were of a little additive effects and instability. The QTLs controlling the traits such as grain weight, grain length, ratio of length to width in grains and heading date were relatively stable. The stable QTLs usually had larger additive effects and were less affected by the environment. The QTLs for the traits of agronomic importance were detected by SSSLs in rice and with high resolution under different environmental conditions. The instability of the QTLs may be the basis of the variation of rice plants during growth and development. It would be the genetic basis for improving yield and quality in rice cultivars by farming methods.