小麦白粉病抗性位点Pm5所在染色体区域的比较作图与候选基因发掘

Powdery mildew caused by Blumeria graminis (DC.) E. O. Speer f. sp. tritici (Bgt) is a serious fungal disease of wheat worldwide and perennial occurred in the wheat growing areas of China. Deployment of resistant cultivars provides an effective approach for disease control to eliminate the use of fungicides and minimize crop losses. Resistance gene diversity can be realized by searching for largely untapped of the rich genetic resources in wheat landraces. The closely linked molecular markers with resistance gene can be used to quickly introgress the desired genes into commercial varieties or pyramiding different resistance genes into a single genotype/cultivar for broad-spectrum resistance in wheat breeding programs. Wheat landraces are abundant in China, and there are numerous unidentified genes for resistance to a wide range of diseases in wheat landraces. A more detailed analysis of selected landraces revealed that some might possess novel genes or alleles that have not been identified. Pm5 is the only one recessive locus and has multiple alleles. Previously results indicate that there probably exist more alleles at Pm5 locus or powdery mildew resistance genes are closely linked to Pm5, clustered together at the distal region of chromosome 7BL in wheat landraces. However, the relationship between them needs more refined studies through molecular markers, allelism test, and spectrum analysis. The objectives of this study were to investigate the allelism of these genes with Pm5 locus, especially genes in Youbailan, Mazhamai and Xiaobaidong; reveal genetic variation of the chromosome region harboring Pm5 locus; fine mapping the powdery mildew resistance genes by molecular markers and comparative genomics analysis and get the closely linked markers of Pm5 locus for marker-assisted selection (MAS). This study will provide a step toward elucidating the genetic basis of powdery mildew resistance loci of Pm5, and offers further possibilities for durable resistance.

小麦白粉病是一种世界性病害，在我国常年发生。实践证明，选育和推广抗病品种是减少药剂使用和降低产量损失的最有效方法。小麦抗病基因常常由于新毒性小种的出现而失去抗性。因此，挖掘新的抗白粉病基因或者利用分子标记技术将多个抗性基因聚合到一个材料中，实现小麦的持久抗性至关重要。Pm5是目前所有抗白粉病基因位点中唯一的一个隐性复等位基因座，已有研究表明，我国小麦农家品种在抗白粉病基因Pm5位点可能存在着丰富的等位变异。本研究将以白粉病抗性较好的3个农家品种游白兰、蚂蚱麦和小白冬麦为主要材料，采用抗谱分析、等位性测验、分子标记技术和比较基因组学等方法，确定该区域内各抗白粉病基因间的关系，构建Pm5位点所在染色体区域的精细遗传连锁图，发掘候选基因，筛选出可用于辅助选择的分子标记，为更好的利用这些抗源，以及深入研究该抗病基因位点提供理论依据。