Fine mapping and candidate gene dissection of the wheat powdery mildew resistance gene PmPBDH

The wheat powdery mildew resistance gene PmPBDH was fine mapped to a 788.20-kb genomic interval on chromosome arm 4AL. The powdery mildew resistance gene PmPBDH was identified in wheat breeding line PBDH1607. To fine map PmPBDH, an F_2:3 population of 5000 individuals derived from the cross PBDH1607 × Huixianhong was used for recombinant screening. Combining PacBio SMRT long-read genome sequencing, PmPBDH is fine mapped to a 788.20 kb interval (chr4A:737865053-738653247 bp) based on the reference genome of Chinese Spring (IWGSC RefSeq v2.1). Comparative genomic analysis reveals poor collinearity of this region across different Triticum species, indicating complex structural variations of this candidate interval. Within this interval, 16 high confidence genes are annotated according to IWGSC RefSeq v2.1. Expression profiling following Bgt inoculation and sequence variation analysis reveals TraesCS4A03G1174000, encoding the RPP13 nucleotide-binding leucine-rich repeat (NLR) protein, as the pivotal candidate gene for PmPBDH. Three closely linked or co-segregated markers are screened for optimizing the efficient transfer of PmPBDH in breeding practices. This study provides valuable genetic resource and molecular tool for improving resistance against powdery mildew in wheat.