中间偃麦草产量性状相关染色体区段的发掘及鉴定

Thinopyrum intermedium possessed many important traits such as disease resistance, durable to abiotic stress, longer spike and more kernels, thus make its valuable gene resources for wheat improvement. Researchers always concentrate on the transfer of genes with resistance to disease and pests, and abiotic stress in T. intermedium to common wheat, rather than the yield related traits. An introgression line, named Shannong304, was developed from cross between wheat cultivar Yannong15 and T. intermedium, and showed valuable characters such as higher biomass, bigger spikes and more kernels per spikes than its wheat parent Yannong15. A recombinant inbred lines (RILs) population was generated by crossing Shannong304 and Yannong15. Genetic compositions and yield related traits of the RILs population were examined in order to identify quantitative trait loci (QTL) with significant contributions to yield or yield related traits under both normal water and osmotic stress conditions. The relationship between these QTLs and introgressed chromosome segments of Th. intermedium were studied, thus to identify those chromosome segments that possessed positive effect to yield related traits such as the spikelets and kernels numbers per spike. Another goal of the study is to develop molecular marker linked with these chromosome segments of Th. intermedium, thus help to identify elite Trititrigia germplasms. The results would provide useful information for understanding Th. intermedium values in wheat improvement.

中间偃麦草是小麦重要的野生近缘植物之一。以往研究中，人们多重视向小麦转移中间偃麦草的优异抗病虫和抗逆特性，关于其对小麦产量相关性状影响的研究较少。课题组前期选育出生长繁茂、大穗多粒的小偃麦种质系山农304，原位杂交和分子标记分析证明其为小麦-中间偃麦草渐渗系，且多个染色体位点结构均发生变化。本研究拟以山农304及其后代RIL群体为材料，结合标记数据与多年多点表型鉴定结果，分析其产量相关性状QTL位点与中间偃麦草渗入区段的关系，筛选对小麦产量构成性状具有正效应的中间偃麦草染色体区段/位点，明确其遗传效应、作用性质；继续培育综合性状较好，产量构成性状突出的小偃麦新种质。研究结果对于促进中间偃麦草在小麦遗传改良中的应用具有重要的理论价值和实践意义。

中间偃麦草具有大穗多花、长势繁茂、抗病性强，耐逆境胁迫等优良特性，是小麦遗传改良中利用较多的野生亲本之一。项目组前期在烟农15和中间偃麦草的杂交后代中筛选到大穗、多花、繁茂性好的小偃麦种质系山农304。本项目综合利用细胞遗传和分子标记技术，证明山农304是一个涉及多条染色体结构变异的小麦-中间偃麦草渐渗系；利用烟农15和山农304杂交，构建了包含296个家系的RIL群体，对其进行了多年多环境性状鉴定；利用SLAF简化测序技术，构建了包含3053个标记的高密度遗传连锁图谱，标记间平均遗传距离为0.46cM；综合表型鉴定结果，定位到172个稳定遗传的QTL，其中41个主效QTL的增效基因来自于SN304，涉及穗长、每穗小穗数、穗粒数、株高、千粒重等13个产量相关性状；分子标记和重测序结果表明部分QTL与中间偃麦草易位片段有关，初步建立了与片段连锁的分子标记；选育出多个产量构成性状突出的次生小偃麦种质系，可用于小麦遗传育种实践。研究结果对于促进中间偃麦草优异基因挖掘，以及小麦种质资源创新具有重要的实践和理论意义。