Fine mapping of a powdery mildew resistance gene PmLF540 from wild emmer wheat

In wheat production, powdery mildew displayed devastating power threatening grain yield and flour quality. To control this disease, utilization of resistance genes represents the most efficient and environmentally friendly strategy. The wild emmer wheat accession LF540 demonstrated high level of resistance against powdery mildew. Genetic analysis revealed that a single dominant gene, tentatively named PmLF540, conferred this resistance at the seedling stage. Employing bulked segregant exome capture sequencing and 2000 F_2:3 families, PmLF540 was fine mapped to a 681.5-kb interval (Chr4A_712370609-Chr4A_713052118) based on the reference genome of wild emmer wheat v1.0 (accession Zavitan). Collinearity analysis indicated that this candidate interval has poor collinearity between different Triticum species, suggesting that PmLF540 was mapped to a complex genomic region. Expression pattern against both avirulent and virulent Bgt isolates and haplotype analysis of the candidate genes within this interval revealed TRIDC4AG068820, encoding a typical nucleotide-binding domain and leucine-rich repeat resistance protein, as the pivotal candidate gene for PmLF540. Fifteen closely linked markers and a gene-specific marker KASP540-1 for TRIDC4AG068820 were screened for facilitating the efficient transfer of PmLF540 in breeding practices.