小麦籽粒大小基因/QTL精细作图

Grain weight is one of the three direct components of grain yield, and the differences in grain weight between genotypes are affected by the grain size, i.e. grain length (GL), grain width (GW), ratio of GL/GW and factor form density (FFD). We have obtained a mutant line M8008, which was identified from the wheat cultivar Yannong 15 induced by EMS. The thousand-grain weight (TGW) of M8008 is 11 g higher than Yanong 15. We also constructed two sets of recombinant inbred lines (RILs) derived from the crosses of "Shanong 0431 / luimai 21" and "Tainong 18 / linmai 6", which the TGW were 17 g and 12 g differences between the two pair of parents, respectively. Using the RILs of "Shanong 0431 / luimai 21", we constructed a molecular linkage map consisted of 740 loci, and carried out QTL mapping for grain size traits in six environments. Of which, a strongest stable and major QTL cluster were located on chromosome 5B including QGl, QGlw and QTgw. Furthermore, more than 600 polymorphic loci were obtained using the RILs of "Tainong 18/linmai 6". The objectives of this study were: (1) to construct the RILs and ILs derived from M8008 and Yanong 15 or Shijiazhuang 54, and the ILs of "Shanong 0431 / luimai 21" and "Tainong 18 / linmai 6"; (2) to screen whole genome using molecular markers, and conduct QTL mapping for grain size traits according to field trials of multi-years and sites; and obtain the important marker regions of QTLs or QTL clusters; and (3) to carry out fine mapping for the important regions, and locate the important genes/QTLs according to field trials of multi-years and sites.

粒重是构成小麦产量的三因素之一，受粒长、粒宽、粒长/粒宽、FFD等籽粒大小性状影响。我们利用EMS处理小麦品种烟农15，获得了大粒突变体M8008，其千粒重比烟农15增加11g。还构建了2个RIL群体：山农0431/鲁麦21、泰农18/临麦6号（亲本千粒重分别相差17g和12g）。前者绘制了740个位点分子标记遗传图谱，进行了6个点次试验和籽粒大小QTL分析。在5B发现了一个稳定的籽粒大小的主效QTL簇。后者分子标记分析趋于完成，获得了600多个多态性位点。本项目在此基础上：（1）构建M8008与烟农15和石家庄54的RIL和IL群体，和两个组合的IL群体。（2）对RIL群体进行分子标记全基因组扫描，结合多年多点试验结果，进行QTL分析，获得重要目标性状QTL（簇）所在的染色体及其标记区域。（3）利用IL进一步构建精细遗传图谱，结合多年多点试验结果，进行重要目标性状基因/QTL的精细作图。

利用大粒突变体和RIL群体进行了籽粒大小QTL分析，绘制了2张高密度遗传图谱：TL-RIL群体图谱包括10739个差异位点（5399个独立位点），SL-RIL群体图谱包括5963个差异位点（4565个独立位点）。获得了20余个稳定的籽粒大小QTL及其紧密连锁的分子标记；克隆基因与千粒重相关的基因（TaSnRK2.10-4）并开发了其功能标记。获得发明专利2项，获国家科技进步二等奖1项（第5位），发表论文1篇，投稿论文3篇，培养博士研究生3名、硕士研究生4名。遗传图谱的构建为进一步研究重要农艺性状奠定了基础，稳定QTL及其分子标记，可为分子育种和相关基因克隆提供参考。