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

Wheat powdery mildew ( f. sp. , , recently clarified as s. str.), is one of the most destructive diseases of wheat. is a nucleotide-binding leucine-rich repeat (NLR) gene that confers race-specific resistance to . Allelic variants (, , and ) were found in and , the wild progenitors of wheat. In the present study, we studied the diversity of the locus in a large set of wheat germplasm and found 20 tetraploid wheats harboring the alleles, which correspond to three novel haplotypes (HapI-HapIII). HapI ( allele) and HapII ( allele) were present in domesticated tetraploid wheats, whereas HapIII ( allele) was identified in wild tetraploid . 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 haplotype . Infection tests showed that HapII-carrying lines display a partial resistance response to , while HapI was susceptible. Our results provide insights into the genetic evolution of the locus and potential valuable alleles for powdery mildew resistance breeding.