Haplotype Analysis Sheds Light on the Genetic Evolution of the Powdery Mildew Resistance Locus Pm60 in Triticum Species

Xuhui Huang,Xueli Jin1,Xiaojie Ren,Wenxuan Wu,Wenjun Ji,Lihua Feng,Bo Jiang,Ming Hao,Shunzong Ning,Zhongwei Yuan,Lianquan ZhangBihua Wu,Dengcai Liu,Zhen-Zhen Wei and Lin Huang

Wheat powdery mildew (Blumeria graminisf. sp.tritici,Bgt, recently clarified asB. graminiss. str.), is one of the most destructive diseases of wheat.Pm60is a nucleotide-binding leucine-rich repeat (NLR) gene that confers race-specific resistance toBgt. Allelic variants (Pm60,Pm60a, andPm60b) were found inTriticum urartuandT. dicoccoides, the wild progenitors of wheat. In the present study, we studied the diversity of thePm60locus in a large set of wheat germplasm and found 20 tetraploid wheats harboring thePm60alleles, which correspond to three novel haplotypes (HapI–HapIII). HapI (Pm60allele) and HapII (Pm60aallele) were present in domesticated tetraploid wheats, whereas HapIII (Pm60aallele) was identified in wild tetraploidT. araraticum. A sequence comparison of HapII and HapIII revealed that they differed by three SNPs and a GCC deletion. Results of the phylogenetic analysis revealed that HapII was more closely related to the functional haplotypeMlIW172. Infection tests showed that HapII-carrying lines display a partial resistance response toBgt#GH, while HapI was susceptible. Our results provide insights into the genetic evolution of thePm60locus and potential valuable alleles for powdery mildew resistance breeding.