小麦品种良星99抗白粉病新基因Pm52的精细定位

Wheat powdery mildew occurs in over 600 million hectares annually in China, which seriously threatens wheat production. Liangxing 99 with resistance to powdery mildew is a promising commercial wheat cultivar released in the national level. We identified a new gene for resistance to powdery mildew in Liangxing 99, which was mapped in an 1.1 cM interval in the deletion bin 2BL2-0.36-0.50 on the long arm of chromosome 2B. Based on its unique position on chromosome 2BL, this gene was officially designated Pm52. This project will be initiated to finely map Pm52 using comparative genomics analysis and establish the technique for efficient application of this gene. Focus will be given to the following areas: (1) to develop wheat EST-based markers taking the advantage of collineality of the genomic sequences between wheat and the Gramineous crops and/or grass, such as barley, rice, Brachypodium distachyon, as well as Chinese Spring 454 sequence, A genome of Triticum uratu and D genome of Aegilops tauschii draft sequences. The markers will be used for constructing high density genetic linkage map aiming at fine-mapping of gene Pm52; (2) to establish molecular marker-assisted selection for Pm52 using tightly linked and/or co-segregated markers to facilitate application of this gene in breeding programs; and (3) to determine the effectiveness of Pm52 in the major wheat producing regions by means of precise tests for disease resistance, which is useful in prediction of effective areas for Pm52 application. The results of this study will greatly facilitate the efficient application of the newly identified gene Pm52 both in wheat production and in development of disease resistant cultivars.

我国白粉病每年发生约1亿亩，严重威胁小麦安全生产。良星99是通过国家审定的抗病品种，我们在良星99的2BL染色体bin 2BL2-0.36-0.50上1.1cM区间上发现一个抗白粉病新基因，被正式命名为Pm52。本研究拟采用比较基因组学分析精细定位Pm52，建立Pm52高效利用技术。研究内容包括：(1)利用大麦、短柄草、水稻，以及普通小麦、A和D基因组序列信息，开展比较基因组学研究，利用禾本科作物基因组区段的共线性关系，开发以小麦EST为基础的分子标记，通过大规模分离群体的遗传连锁分析，构建高密度遗传连锁图谱，精细定位Pm52基因；(2)利用紧密连锁或共分离分子标记，建立Pm52的分子标记辅助选择体系；(3)通过抗病性精准鉴定，阐明Pm52在小麦主产区的利用价值和范围，指导其有效利用和布局。研究结果必将极大地促进良星99的抗病新基因Pm52在生产和抗病育种上的高效利用。

小麦品种良星99是黄淮冬麦区和北部冬麦区大面积推广的优良小麦品种，累计推广面积达5000多万亩。此外，良星99还作为优异亲本，培育出一大批小麦新品种。良星99的抗白粉病基因被定位于2BL染色体，正式命名为Pm52。本项目的目的是精细定位Pm52基因；建立Pm52基因的分子标记辅助选择技术，同时明确Pm52的利用价值。我们利用比较基因组学技术和中国春参考基因组序列共开发了1274个分子标记，获得22个基因连锁标记。利用8820株良星999×中作9504的F2代作图群体，构建了高密度遗传连锁图谱，将Pm52基因精细定位于2BL染色体0.21 cM区间，对应中国春参考基因组5.6 Mb（581242466-586768319）物理区间。这个结果为Pm52基因的图位克隆奠定了坚实的基础。Xicscl817和Xicsl234与Pm52紧密连锁，可用于Pm52基因的分子标记辅助选择，提高Pm52基因的检测效率和准确性。通过各地123个白粉菌菌株的抗性评价，良星99对山东、河北、河南、山西、北京等地80%的菌株具有抗性，而且通过连续7年的鉴定，良星99在成株期表现免疫和高抗的表现型。这表明Pm52基因在我国北方广大小麦主产区具有较好的抗性和利用价值。