Pathogenic Types And Virulence Genes Frequency Of Puccinia Triticina In China In 2006

Wheat leaf rust is a serious fungal disease causing heavy loss of wheat production in the world.Utilization of resistant cultivars has been considered as the most economical and effective approach to control leaf rust in wheat.As one of main important causations, changes of population composition of the Puccinia triticina result in the "breakdown" of resistant wheat cultivars.Therefore,investigations of the pathotypes and composition of P. triticina and the frequency of virulence genes play an important role in breeding new resistant cultivars and in deploying of wheat cultivars.Five hundred and sixty collections of P.triticina were obtained from 14 provinces of China,including Hebei,Heilongjiang,Henan,Jiangsu,Shandong,Liaoning,Shanxi,Hubei, Jilin,Anhui,Gansu,Neimenggu,Xinjiang and Qinghai,to determine the virulence of the wheat leaf rust fungus in 2006.433 single uredinial isolates of P.triticina were obtained from the wheat leaf rust collections and tested for virulence phenotype on 43 near isogenic lines(or monogenic lines,or cultivars)in the seedling stage.One hundred and forty seven virulence phenotypes were found in China in 2006. Among virulence phenotypes,FHTT was dominant virulence phenotype with the frequency 11.1%while others remained less than 6.0%.Except for FHTT,there were 15 virulence phenotypes with the frequency of more than 1.0%,including FHKT(6.0%), FHJT(5.1%),FHST(4.6%),PHTT(3.9%),THTT(3.0%),FHRT(3.0%),FHSS(3.0%), FHHT(2.8%),KHST(2.1%),FHGT(2.1%),PHKT(1.6%),PHSS(1.6%),PHRT(1.4%), FHNS(1.4%)and THST(1.2%).Virulence frequency of 16 virulence genes(V1,V2a,V9, V15,V19,V24,V28,V30,V32,V36,V38,V41,V43,V45,V46 and V50)were lower than 40%,and V9,V24 and V38 could not be detected in China,19 virulence genes(V2b,V2c, V3,V3bg,V10,V11,V14a,V14b,V14ab,V16,V17,V18,V21,V25,V26,V33,V34, V33+34 and VB)were above 70%,and 8 virulence genes(V3Ka,V20,V23,V29,V39,V40, V42 and V44)were 40%～60%in 2006.In detail,this study indicated that Lr1,Lr2a,Lr9, Lr15,Lr19,Lr24,Lr28,Lr30,Lr32,Lr36,Lr38,Lr41,Lr43,Lr45,Lr46 and Lr50 conferred higher resistance to P.triticina,and Lr2c,Lr3,Lr3bg,Lr10,Lr11,Lr14a,Lr14b, Lr14ab,Lr16,Lr17,Lr18,Lr21,Lr25,Lr26,Lr33,Lr34,Lr33+34 and LrB had lost resistance to P.triticina in China.Interestingly,Lr9,Lr24 and Lr38 still held strong resistance to P.triticina in 2006,and they might have more potentials to utilizilized in Chinese wheat leaf rust breeding in future.In addition,the dominant pathotypes and frequency of leaf rust isolates were obvious differences among Hebei,Henan,Shandong, Shanxi,Helongjiang and Jilin provinces in 2006,and isolates from different areas showed much difference in composition and virulence frequency of wheat leaf rust virulence genes, which indicated that there was a certain correlation between virulence groups and geographical areas.