小麦地方品种中与强筋相关新基因的挖掘和定位

Germplasm is the carrier of genes and the basis of gene discovery. To date, there are large numbers of unexploited favorable genes in wheat landraces. However, due to these landraces have many unfavorable phenotypic traits and the favorable genes often have linkage drags, the favorable genes are difficult to be detected. AB-QTL is an effective method that integrate the process of exploiting favorable genes from unadapted germplasm and introgress them into elite breeding materials. . In the past years, we analyzed the bread-quality of 444 Shangdong wheat landraces and found some landraces with very good bread-making quality, but without reported positive glutenin subunits. To detect the novel genes which contribute to the high bread-making quality in these landraces, two advanced backcross populations derived from a cross between the landrances and a elite variety have been developed. . The present study will map these genes which positively contribute to bread-making quality using AB-QTL strategy. It will provide valuable genetic resources for wheat quality improvement and lay the foundation for further cloning of these elite genes.

种质资源是基因的载体，是基因发掘的基础。小麦地方品种中存在大量的尚未开发利用的优异基因，但是由于这些种质资源的不利性状多，优异基因往往与不利基因连锁，使优异基因不易被检测到。AB-QTL方法是从适应性较差的种质资源中发现有价值QTL并将其转移到骨干育种材料中去的有效方法。. 我们在对444份山东地方小麦品种进行品质鉴定的过程中,发现了一批强筋但无已知优质谷蛋白亚基的品种，为了挖掘其中的优质强筋新基因，我们利用这些地方品种和一个主推品种构建了两个高代回交群体。本研究拟利用AB-QTL方法挖掘这些地方资源中的优质强筋新基因位点；为小麦优质基因的克隆打下基础，为品质育种和改良提供可以利用的种质和基因资源。

高密度遗传连锁图是QTL精细定位的必要条件，我们利用55K SNP芯片对来自地方品种半芒子和济麦22构建的186个F6代重组近交系进行基因型分析。构建了一个高密度遗传连锁图，包含10813个SNP，覆盖5528.5 cM，标记间的平均距离为0.51 cM。对蛋白质含量、硬度、吸水率、形成时间、稳定时间、粉质质量指数和沉降值等7个品质性状利用完全区间作图法进行QTL分析，共检测到79个QTL，其表型变异率为1.22~32.50%。其中，25个稳定QTL能在2-3个环境中检测到。一个重要的QTL定位在4D染色体的AX-109230716-AX-110572006区间，该位点对6个品质性状的QTL连锁，其正向等位变异来自地方品种半芒子。另外，6A染色体上定位了与硬度、形成时间、稳定时间、粉质质量指数和沉降值都有关的一个QTL簇，能解释其表型变异率的7.12-16.51%。