Mapping And Application Of The Powdery Mildew Resistance Gene In Triticum Dicoccoides 'DIC479'

Wheat powdery mildew is caused by the fungus Blumeria graminis f.sp.tritici.It occurs mainly in wheat production area with humid conditions.Along with the change of farming system and production conditions,powdery mildew has become a serious disease for global wheat production.Pyramiding of disease resistance genes,breeding and application of disease-resistant varieties appear to be the most economic,safe and effective method to control the disease.Exploration and deployment of powdery mildew resistance genes play a primary role for developing disease-resistant varieties.Wild emmer?Triticum dicoccoides,AABB,2n=4X=28?,carrying many disease resistance genes,is an important resource for wheat genetic improvement.In this study,we targeted the wild emmer'DIC479',an accession highly resistant to wheat powdery mildew,analyzed its genetic base for disease resistance,and mapped the gene.This work founded future studies on gene function and underlying mechanisms,and generated novel resources for disease resistance breeding in wheat.In this study,DIC479 and‘Langdon'?Triticum dicoccum Schrank?were used to generate the F₁ plants,F₂ populations?pop2 and pop3000?and their F₃ families,F_2:3subpopulation and their F_2:4:4 families,which were used for genetic analysis and gene mapping for powdery mildew resistance in DIC479.Using marker-assisted selection,the powdery mildew resistance of DIC479 has been transferred into common wheat?T.aestivum?.Major results are as follows:1.In greenhouse condition,we tested DIC479,Langdon and their cross progenies for their reaction to powdery mildew.The F₁ plants were high resistant;plants of the F₂population?pop2?and two F_2:3:3 subpopulations?pop731 and pop2512?segregated for resistance?R?and susceptibility?S?with 3R vs.1S;lines of the corresponding F₃ and F_2:4families segregated for homozygous resistance?RR?,hetetrozygous?RS?,and homozygous susceptibility?SS?with 1RR vs.2RS vs.1SS.Therefore,the powdery mildew resistance in DIC479 inherits as a single dominant Mendelian trait.We temporarily named the underlying gene as PmD479.2.We performed bulked segregation analysis?BSA?on ten susceptible F₂ plants of pop2 by using the wheat 90K SNP assay,and mapped the PmD479 gene on the long arm of chromosome 2B.We then developed 26 linked markers to PmD479 using the Chinese spring nulli-tetrasomics and collinear information of Aegilops tauschii,barely,and rice genomes.The PmD479 gene was mapped between sdau149 and sdau148B,which is about an 0.5cM interval.The sdau149 is only aoubt 0.17cM away from PmD479,and could facilitate marker-assisted selection.3.To utilize PmD479 for disease resistance breeding in wheat,DIC479 and/or F₃resistant plants were used to cross with selectged common wheat.Fourteen BC₁F₁ lines has been obtained with desirable resistance to powdery mildew.