小麦农家品种白大头成株抗条锈基因YrBai的精细定位

Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), is one of the most important diseases that cause substantial yield losses in common wheat (Triticum aestivum) in China and other parts of the world. The most effective, economical and environmentally sound means of controlling the disease is host resistance. Resistance gene diversity can be realized by searching for largely untapped of the rich genetic resources in wheat landrace. The closely linked molecular markers with resistance gene can be used to quickly introgress the desired genes into commercial varieties in wheat breeding programs. In our previous study, Chinese wheat landrace Baidatou showed a high level of adult-plant resistance to stripe rust in our greenhouse and field tests. We characterized the stripe rust resistance gene in wheat Baidatou as adult-plant resistance gene and mapped the gene to the short arm of chromosome 6D, temporarily designated YrBai. And four polymorphic SSR and SRAP markers were linked to YrBai. But the six markers played a limited role in fine mapping of YrBai. A large mapping population, derived from the crosses between susceptible genotype Mingxian 169 and Baidatou (YrBai), were used for genetic analysis and fine mapping. The molecular marking techniques such as SSR, Caps, EST-STS, etc, will be used in fine mapping of YrBai. To develop additional markers, wheat genome sequence can be adopted for developing closely linked markers to reduce the genetic interval around YrBai. Specific markers will also be screened, which can be used for the identification of the target gene. This research will provide the elite genetic resources, important stripe rust resistance gene and the linkage markers for improvement of wheat resistance by marker-assisted selection and lay the foundation for the map-based cloning of YrBai.

小麦条锈病是世界范围内重要的小麦病害之一，严重威胁我国粮食安全。从农家品种挖掘和鉴定新的抗病基因，可以丰富我国抗条锈基因库，对提高我国小麦抗条锈病水平具有重要意义。本课题组前期已鉴定白大头含有成株期抗条锈病主效基因YrBai，并将YrBai定位在小麦6DS染色体上，获得了与YrBai连锁的4个SSR和2个SRAP标记。但是获得的标记与YrBai距离较远，无法满足精细定位的需要。因此本项目拟在前期研究基础上，构建大的作图群体，利用已公布的小麦基因组相关序列设计引物，筛选与抗病基因更紧密连锁的分子标记，构建抗条锈病基因的精细遗传连锁图谱，利用特异性标记对目的基因载体材料和国内外重要小麦品种进行分子检测。白大头与当前主栽品种杂交过程中，利用连锁标记辅助选择，可同时创建出抗病新种质。本项目的完成将为分子标记辅助选育抗条锈病小麦提供宝贵的种质材料、优良基因和标记信息，同时为克隆YrBai奠定基础。

小麦条锈病是世界范围内重要的小麦病害之一，严重威胁我国粮食安全。从农家品种挖掘和鉴定新的抗病基因，选育抗病品种可加速解决条锈病问题。本项目对白大头携带的成株期抗条锈病基因YrBai进行了精细定位。本项目采用群体分离分析法 (Bulked Segregant Analysis, BSA)，结合多种分子标记技术，构建抗病基因精细YrBai的遗传连锁图谱。利用Diversity Arrays Technology Pty/Ltd技术获得了距离YrBai最近的遗传距离为0.8cM两个分子标记（1082100和1228999）；利用简化基因组测序技术获得了5个共分离的分子标记（186543、17325、16308、17356、19066），其中将16308和17356开发成能用于分子辅助育种的SSR标记。本项目将为分子标记辅助选育抗条锈病小麦提供宝贵的种质材料、优良基因和标记信息，同时为克隆YrBai奠定了良好的基础。因此，下一步开展候选基因的筛选及验证，以明确小麦农家品种持久抗条锈性的机制，解决小麦抗条锈性易丧失的问题，以达到小麦分子辅助抗条锈的目的。