应用剩余杂合体衍生群体定位水稻粒重粒形QTL

【目的】粒重粒形是影响水稻产量和品质的重要因素,由大量数量性状座位(QTL)控制,其作用变异极大,但以往研究主要着眼于效应大的QTL。本研究在剔除主效QTL影响的基础上,开展微效粒重粒形QTL分析。【方法】在前期研究基础上,从原群体挑选出1个剩余杂合体单株,构建了在主效QTL区间纯合、在其余区域中13个区间分离的群体,种植于浙江杭州和海南陵水,测定千粒重、粒长和粒宽。【结果】采用Windows QTL Cartographer2.5,检测到22个QTL,分布于10条染色体的12个区间,其中,10个区间在两地均呈显著作用,2个区间仅在杭州试验中呈显著作用。进一步从该群体筛选出1个只在其中4个QTL区间杂合的单株,自交构建分离群体,验证了这4个区间对粒重粒形的效应。【结论】排除主效QTL有利于提高微效粒重粒形QTL的检测功效;虽然微效QTL可能易受环境和遗传背景影响,但仍可具有稳定表现。这些结果为进一步开展粒重粒形QTL的精细定位、克隆和分子标记辅助选择奠定了基础。

Identification of QTL for Grain Weight and Grain Shape Using Populations Derived from Residual Heterozygous Lines of indica Rice

【Objective】Grain weight and grain shape are important factors influencing grain yield and quality in rice. There are quantitative traits controlled by a large number of quantitative trait loci (QTL) that vary greatly in effect, but not much attention has been paid to minor QTL. This study was conducted to detect minor QTL for grain weight and shape in the absence of major-QTL segregation. 【Method】 Following results of a previous QTL mapping study, a residual heterozygous plant was identified from the original population. The new population derived was homozygous in regions where major QTL for grain weight and shape were detected in the previous study, but segregated in 13 segments of other genomic regions. The population was planted in Hangzhou, Zhejiang and Lingshui, Hainan. Thousand-grain weight, grain length and grain width were tested and used for QTL analysis using Windows QTL Cartographer 2.5. 【Result】A total of 22 QTL were detected, distributing on 12 intervals of 10 chromosomes. Ten of them were significant in both locations, and the other two were detected in Hangzhou only. One plant that was only heterozygous in four of the 12 QTL regions was identified, from which one new population was constructed and tested. The QTL effects of the four regions were well validated. 【Conclusion】Our results indicate that the power of detecting minor QTL could be efficiently increased by eliminating the influence of major-QTL segregation. It is also suggested that minor QTL could have a stable effect though it is believed that they are generally subjected to large influence of the genetic background and environmental conditions. Our results also lay a foundation for fine mapping, cloning and marker-assisted selection of minor QTL for grain weight and grain shape in rice.