实心小麦‘86-741’壁厚基因Cwt-1的精细定位及其与产量性状的关系

Lodging is a major constraint limiting wheat production when targeting high yields. The solid-stemmed wheat with thicker-culms can increase the lodging resistance substantially, conquering the lodging risk caused by raising plant height to increasing biomass at crop breeding for super high yield. In our previous study, a gene associated with culm wall thickness Cwt-1 was identified on chromosome arm 3BL from a solid-stemmed wheat germplasm ’86-741’ using bulk segregant analysis (BSA), and then the results of QTL analysis for the wall thickness of each culm internode using a recombinant inbred line (RIL) population showed that the culm wall thickness was also controlled by other minor QTLs on other chromosome arms except for Cwt-1 on 3BL. In this study, we are trying to (1) obtain molecular markers tightly linked to Cwt-1, using a large secondary F2 population and derived recombination lines with a series of related molecular markers developed based on sequence from SNP-chip information, EST sequence and other available related wheat genomic sequence, including SSR markers and other known genetic markers; (2) interpret the genetic effect of Cwt-1 on wall thickness of each culm internode on detail and the relationship between Cwt-1 and yield-related traits, using the RIL population and the near-isogenic lines (NILs). The goal of the study was fine mapping of Cwt-1 and defining its genetic effects on each culm internode and yield related traits, establishing the foundation for cloning and utilization of this gene.

在小麦高产育种中，倒伏仍然是一个主要限制因素，实心小麦的茎秆壁较厚，具有很好的抗倒性，可以克服在超高产育种中适当提高株高带来的倒伏问题。本课题组在前期的研究中通过集团分离分析法从实心小麦‘86-741’ 3BL上鉴定出了一个与壁厚相关的基因Cwt-1；利用重组自交系（RIL）对茎秆不同节壁厚的QTL分析表明该性状还受到其它微效QTLs的控制。本研究拟通过构建次级F2大群体以及Cwt-1区间内的一系列重组体，利用SNP标记、EST标记、SSR标记以及相关的基因组序列开发的标记等，获得与Cwt-1紧密连锁的标记；同时利用‘86-741’与‘川麦42’重组自交系、近等基因系研究该基因对于茎秆各节壁厚的遗传效应以及与产量及其相关性状之间的具体关系。本研究的目的是从遗传上精细定位Cwt-1基因，阐明其对茎秆各节壁厚以及产量性状的遗传效应，为该基因的克隆和应用奠定基础。

实心小麦茎秆壁较厚，具有较高的茎秆机械强度，可以有效的防止麦茎蜂的危害，同时在解决超高产育种中通过适当提高株高带来的倒伏问题具有很好的前景。本研究利用川麦42和实心小麦86-741 RIL群体，构建了高密度SNP遗传图谱，并对群体茎秆各节壁厚、机械强度以及产量相关农艺性状进行了QTL分析，结果显示茎秆壁厚、机械强度相关QTL与产量相关QTL之间相互独立，茎秆壁厚显著影响茎秆的机械强度；利用Xsaas008标记对BC5F2进行基因型分析，结果显示Cwt-1对倒第二节、倒第三节的茎秆壁厚的影响大于其它节，Cwt-1基因表现为完全显性遗传，同时Cwt-1基因对产量相关性状的影响不显著，为创制厚茎秆壁的高产材料提供了理论指导；根据之前定位的主效QTL区间，利用1800个BC3F4群体将Cwt-1基因定位在Xgwm247与Xgwm547之间，并与Xsaas008共分离；利用182个微核心种质材料，对Xgwm340、Xgwm247、Xsaas008以及Xgwm547进行关联分析，其中Xsaas008和Xgwm547与壁厚性状相关性程度大于Xgwm247，表明Cwt-1基因位于Xsaas008与Xgwm547之间，为进一步克隆该基因奠定了基础。