Fine Mapping Of The Major QTL QYm.nau-2D Confering Resistance To Wheat Yellow Mosaic Virus In ’Yining’ Wheat

Wheat yellow mosaic(WYM),caused by wheat yellow mosaic virus(WYMV)is a soil-borne viral disease,transmitted by Polymyxa graminis.This disease has become one of the most serious diseases affecting wheat production in China,usually causing yield losses up to 50%.In previous research,a RIL population derived from a cross between ’Yining’ wheat(resistant variety)and ’Zhen 9523’(susceptible variety),was used to map the resistant QTL.A major QTL QYm.nau-2D,which could explain 85.73%phenotypic variance,was mapped on chromosome 2D.A secondary F2 population derived from the cross between’RIL11-14’(one of the resistant RIL lines containing only QYm.nau-2D)and ’Zhen 9523’was used for further fine mapping and the QYm.nau-2D was mapped between markers Xcfd267 and 2EST811.In this study,a F2 population derived from a cross between ’2011I-78’(T.aestivum cv Chinese Spring-Ae.tauschii 2D substitution,susceptible to WYMV)and ’Yining’ wheat was constructed and used to further map the resistant QTL QYm.nau-2D.The main results obtained were as follows:(1)Genetic analysis of the ’20111-78 X Yining wheat’ F2 population showed that the segregation of resistant and susceptible phenotypes fit the ratio of 3:1(x2=0.56,x20.05=3.84).This confirmed that the WYMV resistance in ’Yining’ wheat was controlled by a single dominant gene.Using the mapping population,the QYm.nau-2D was mapped between the markers Xwmc41 and Xgwm349,with genetic distances of 0.9cM and 5.9cM,respectively.(2)One hundred and thirty-one EST-SSR primer pairs were designed by using the released Chinese Spring reference sequences and wheat EST database.Among them,7 showed polymorphism between the two parents.Ninty-seven primer pairs were designed based on the Ae.tauschii 2D reference sequences,and 11 showed polymorphism between the parents.(3)The individuals of the F2 popolation,and the selected susceptible individuals from F2:3 and F2:4 popolation(900 individuals in total)were used to screen the recombinants using markers 2ESTJ8 and 2D-SSR-10.A total of 77 recombinants were identified and QYm.nau-2D was mapped between marker 2ESTB8 and markers 2ESTK2,2D-SSR-L-12,covering a physical distance of about 28Mb.(4)Three markers,Xwmc41,Wxe1339 and Xwmc181,were used as diagnostic markers to analyze 195 wheat lines with known WYMV phenotype.Markers Xwmc41,Wxel339 and Xwmc181 could be used as diagnostic marker for marker-assisted selection of QYm.nau-2D in wheat breeding.