Genetic Analysis And Fine Mapping Of Major Gene Resistance To Powdery Mildew In Wheat

Wheat is major grain crop for people, which is suffering the challenge of rust diseasegibberellic disease and powdery mildew and other various diseases. Powdery mildew hasheavy harm on wheat production, affects yield and quality of wheat. We could use chemicalsprevent wheat from powdery mildew, but chemicals is higher poisonous, it can causeenvironment pollution to use vast chemicals long time. So breeding wheat resistance speciesis the most safe and effective method. The resistant material0911-3and WP6192of this studyare F8stable plant breeding from the cross offsprings of Triticum polonicum L.×Zhong13.For fine mapping gene resistance to powdery mildew in resistant material WP6192, we cancombine BSA and AFLP molecular marker technique based on analyzing conventionalgenetic law.In order to realize the inheritance law of powdery mildew resistance in wheat0911-3, six populations （P1、P2、 F1、BC1、 BC2and F2） were from cross of0911-3×1130-2were used for studying the inheritance of resistance to powdery mildew by the mixed majorgene+polygene inheritant model with multiple generations analysising method with usingmaximum disease severity and leaf area under disease progress curve as adult plant resistanceindex. The results were:1. The inheritance of powdery mildew resistance of wheat0911-3of two adult plantresistance index was consistent, both were two pairs additive-dominant-epitasis major genes+additive-dominant-epitasis polygene model （E model）; Two major genes was negativeadditive effects, which can enhance resistance;There were variety of effects between twomajor genes, which can enhance resistance; The major gene plus poly-genes heritability of theF2was the highest in segregative generation, the heritability of MDS and AUDPC were91.87%and92.22%.2. WP6192was female parent, Xiaoyan166was male parent, cross group. Throughidentifying resistance to wheat powdery mildew of P₁、P₂、F₁、F₂、BC₁、BC₂and F2:3family after artificial inoculation in the field May,2012. The results showed:21plants werehigh resistant to powdery mildew in F₁; all149plants of backcross group WP6192/Xiaoyan166//WP6192BC1were resistant to powdery mildew; the number of resistance was61andthe number of susceptibility was60in backcross group WP6192/Xiaoyan166//Xiaoyan166BC2,the ratio of resistance and susceptibility was1:1. This showed the resistance of WP6192was dominant.240was number of resistance and the number of susceptibility was84in F2, the ratio of resistance and susceptibility was3:1. Through identifying resistance to powderymildew of F2:3family plants in the seeding, we can distinguish homozygous resistant withheterozygous, the results was the number of homozygous was70，during resistant plants，the number of homozygous was149，the number if susceptible plants was84. In addition theratio was1:2:1in F2:3family. So, the resistant gene to wheat powdery mildew of WP6192was a dominant gene, which was named Pmwp6192temporarily.3. Using AFLP molecular marker technique to fine mapping Pmwp6192. The analyzingpopulation was F₂population from the cross of WP6192and Xiaoyan166.Using bulkedsegregation analysis （BSA） method to screen1280pairs of AFLP markers, we get4pairsAFLP markers with polymorphism. Identifying this markers with polymorphism using F2small population （46plants）, only four pairs marker with polymorphism in F2smallpopulation, this were: X_P-AGA/M-GAC、X_P-GGA/M-GAC、X_P-CCA/M-GTA、X_P-TGA/E-ACA.4. XP-AGA/M-GAC、 XP-GGA/M-GAC、 XP-CCA/M-GTA、 XP-TGA/E-ACAmarkers with stablepolymorphism gene amplificat in F2large population （303plants） for studying the relationshipbetween markers and resistant gene. Using software Mapmaker/Exp V3.0to calculate andanalysis the genetic distance between markers and resistant gene, the results showed two pairsAFLP markers X_P-CCA/M-GTAand X_P-TGA/E-ACAwere linked to wheat resistant gene PmWP6192.These two AFLP markers, X_P-CCA/M-GTAand X_P-TGA/E-ACAlocated in P_mwp6192two sides, thegenetic distance was0.9cM and4.7cM respectively, which laid a foundation for the gene ofmolecular marker assisted selection.