Mapping of powdery mildew resistance genes transferred to common wheat from wild emmer wheat revealed three functional Pm60 haplotypes

Abstract

Powdery mildew (PM), caused by f. sp (), is one of the destructive wheat diseases worldwide. Wild emmer wheat ( ssp. , WEW), a tetraploid progenitor of common wheat, is a valuable genetic resource for wheat disease resistance breeding programs. We developed three hexaploid pre-breeding lines with PM resistance genes derived from three WEW accessions. These resistant pre-breeding lines were crossed with susceptible common wheat accessions. Segregations in the F populations were 3 resistant: 1 susceptible, suggesting a single dominant allele in each resistant parent. Mapping of the resistance gene in each line indicated a single locus on the long arm of chromosome 7A, at the approximate location of previously cloned from . Sanger sequencing revealed three different haplotypes (Hap 3, Hap 5, and Hap 6). Co-segregating diagnostic markers were developed for identification and selection of each haplotype. The resistance function of each haplotype was verified by the virus-induced gene silencing (VIGS). Common wheat lines carrying each of these haplotypes were resistant to most isolates and differences in the response arrays suggested allelic variation in response.