Genetically Dissecting the Novel Powdery Mildew Resistance Gene in Wheat Breeding Line PBDH1607

Abstract

Powdery mildew is one of the most destructive diseases in wheat production. Identifying novel resistance genes and deploying them in new cultivars is the most effective approach to minimize wheat losses caused by powdery mildew. In this study, wheat breeding line PBDH1607 showed high resistance to powdery mildew at both the seedling and adult plant stages. Genetic analysis of the seedling data demonstrated that the resistance was controlled by a single dominant gene, tentatively designated <i>PmPBDH</i>. The ΔSNP index based on bulked segregant RNA sequencing indicated that <i>PmPBDH</i> was associated with an interval of about 30.8 Mb (713.5 to 744.3 Mb) on chromosome arm 4AL. Using newly developed markers, we mapped <i>PmPBDH</i> to a 3.2-cM interval covering 7.1 Mb (719,055,516 to 726,215,121 bp). This interval differed from those of <i>Pm61</i> (717,963,176 to 719,260,469 bp), <i>MlIW30</i> (732,769,506 to 732,790,522 bp), and <i>MlNSF10</i> (729,275,816 to 731,365,462 bp) reported on the same chromosome arm. <i>PmPBDH</i> also differed from <i>Pm61</i>, <i>MlIW30</i>, and <i>MlNSF10</i> by its response spectrum, origin, or inheritance mode, suggesting that <i>PmPBDH</i> should be a new <i>Pm</i> gene. In the candidate interval, five genes were found to be associated with <i>PmPBDH</i> via time course gene expression analysis, and thus they are candidate genes of <i>PmPBDH.</i> Six closely linked markers, including two kompetitive allele-specific PCR markers, were confirmed to be applicable for tracking <i>PmPBDH</i> in marker-assisted breeding.