Genetically Dissecting The Novel Powdery Mildew Resistance Gene In The Wheat Breeding Line PBDH1607

Wheat powdery mildew is a major disease that reduces wheat yield and quality.It is caused by the infestation of wheat leaves by Blumeria graminis f.sp.tritici（Bgt）.Powdery mildew may occur in various periods of China,posing a serious threat to my country’s food security production.At present,there are two main ways to control the damage caused by powdery mildew and prevent its spread are cultivating disease-resistant varieties and using drugs.Practice has shown that spraying pesticides can prevent powdery mildew to a certain extent,but it will cause a certain economic burden,and pesticide spraying will pollute the environment more or less,which is not in line with the concept of green,coordinated and sustainable development.Therefore,mining new wheat varieties with high quality,high yield and disease resistance is undoubtedly the most effective and environmentally friendly means to prevent powdery mildew by mining disease-resistant genes.In this study,a wheat breeding line PBDH1607 showed high resistance to powdery mildew at both seedling and adult stages.Genetic analysis demonstrated that the seedling resistance was controlled by a single dominant gene,tentatively designated PmPBDH.ΔSNP-index based on bulked segregant RNA-seq（BSR-Seq）demonstrated that PmPBDH was associated with an ～30.8 Mb（713.5 ～ 744.3 Mb）interval on chromosome arm 4AL.Using newly developed markers,PmPBDH was mapped to a 3.2 c M interval covering 7.1Mb（719,055,516 ～ 726,215,121 bp）.This interval differed from those of Pm61（717,963,176 ～ 719,260,469）,MlIW30（732,769,506 ～ 732,790,522）and MlNSF10（729,275,816 ～ 731,365,462）reported on the same chromosome arm.PmPBDH also differed from Pm61,MlIW30,and MlNSF10 by its response spectrum,origin and/or inheritance mode,suggesting that PmPBDH should be a new Pmgene/allele.In the candidate interval,six genes（TraesCS4A01G476600.2 、 TraesCS4A01G461700.1 、TraesCS4A01G491400.1 、 TraesCS4A01G492900.1 、 TraesCS4A01G474800.1 、TraesCS4A01G487900.1）were found associated with Bgt inoculation using time-course analysis;thus,they are candidate genes of PmPBDH.Six closely linked markers（YTU25-003、YTU25-004、YTU25-007、YTU25-014、YTU25-043、YTU25-044）,including two Kompetitive Allele-Specific PCR ones（KASP25-071、KASP25-073）,were confirmed to be applicable for tracking PmPBDH in marker-assisted breeding.