发掘人工合成小麦中千粒重QTL的有利等位基因

Mining Favorable Alleles of QTLs Conferring 1000-Grain Weight from Synthetic Wheat

以人工合成小麦Am3为供体亲本,普通小麦莱州953为轮回亲本,经5次回交然后自交,培育出含85个株系的F2:3群体。以该群体为材料,用348对多态性SSR标记,进行全基因组扫描,发掘人工合成小麦中千粒重QTL的有利等位基因。利用复合区间作图法检测到3个千粒重QTL,其对表型变异的贡献率为10.90%～33.79%。其中,Am3的等位基因能够增加千粒重2.3～4.8g。相关分析表明,该导入系群体的千粒重与穗粒数、穗数和株高无显著相关性。千粒重QTL与穗粒数、穗数性状的QTL不在同一位置,这有利于高千粒重基因与其他产量性状基因的聚合。采用混合线性模型作图法检测到1个千粒重QTL(QGw.caas-3D),该QTL与环境互作效应小,而且与复合区间作图法在3个环境中都检测到的QTL相同,表明QGw.caas-3D是一个稳定的主效QTL。

In common wheat （Triticum aestivum L.）, 1000-grain weight （TGW） is an important component of grain yield. However, TGW is generally negatively correlated with grain number per spike and spike number per plant and positively correlated with plant height. The aim of this study was to mine favorable alleles of QTLs conferring TGW from synthetic wheat using ad- vanced backcross QTL analysis. A BC5F2：3 population consisting of 85 lines were generated from a cross between Laizhou 953, a Chinese commercial wheat variety, and Am3, a synthetic hexaploid wheat, followed by backcrossing with Laizhou 953 as recurrent parent and selfing. Three hundred and fourty-eight polymorphic SSR markers were used for genotyping. Using composite interval mapping （CIM）, three major QTLs, QGw.caas-IA, QGw.caas-3D, and QGw.caas-4B, with alleles increasing TGW from Am3, were detected in at least two environments. They could explain phenotypic variations ranging from 10.90 to 33.79%. Among the three QTLs, the alleles originated from Am3 could increase 2.3-4.8 g of TGW without decreasing grain number or spike number, or two of them, even without increasing plant height. Using mixed-model composite interval mapping （MCIM）, one QTL （QGw.caas-3D） was detected with no significant interactions across the environment. Moreover, the QTL was at the same interval as the common QTL detected in 3 environments with CIM method. It is suggested that QGw.caas-3D is insensitive to environments, and may be a stable and maior QTL for TGW.