Identification of the resistance gene to powdery mildew in Chinese wheat landrace Baiyouyantiao

Powdery mildew,caused by Blumeria graminis f.sp.tritici(Bgt),is one of the most damaging diseases to wheat in the world.The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic.Wheat landraces are important resources of resistance to many diseases.Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance.The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew.To identify the resistance gene in this landrace,Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F1,BC1,F2,and F2:3were tested with Bgt isolate E09.The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene,tentatively designated Pm BYYT.An Illumina wheat 90K single-nucleotide polymorphism(SNP)array was applied to screen polymorphisms between F2-resistant and F2-susceptible DNA bulks for identifying the chromosomal location of Pm BYYT.A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chromosome 7B,indicating that Pm BYYT may be located on this chromosome.A genetic linkage map of Pm BYYT consisting of two simple sequence repeat markers and eight SNP markers was developed.The two flanking markers were SNP markers W7BL-8 and W7BL-15,with genetic distances of 3 and 2.9 c M,respectively.The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay.The flanking markers of gene Pm BYYT will benefit marker-assisted selection(MAS)and map-based cloning in breeding wheat cultivars with powdery mildew resistance.