东北地区玉米大斑病菌生理分化研究

Identification of Physiological Races of Exserohilum turcicum in Northeastern China

为明确东北地区玉米大斑病菌的生理分化及小种动态情况,分析玉米大斑病加重的原因。采用常规Ht单基因(Ht1、Ht2、Ht3、HtN)鉴别寄主鉴定技术,对2010年采自辽宁、吉林、黑龙江省22个县(市)88份玉米大斑病菌的菌株进行了生理小种鉴定,共鉴定出0、1、2、N、12、1N、23、2N、3N、12N、123N、123、23N和12N号14个生理小种;东北地区大斑病菌生理分化明显,出现了能够克服多个抗性基因的小种,其中,0号和1号生理小种分别占供试菌株的37.5%和20.5%,为优势小种;所鉴定的88个菌株对Ht1、Ht2、Ht3和HtN抗性基因的毒性频率分别为45.5%,30.7%,15.9%,23.7%。研究结果表明,东北地区玉米大斑病菌生理小种组成及种间的变异频率开始趋于复杂化,不断有新小种出现。玉米大斑病菌新小种出现0号和1号以外其他小种,出现频率升高和品种抗性丧失是导致玉米大斑病发生的重要原因。

In order to understand the epidemic factors of northern corn leaf blight in northeastern China,the physiological differentiation and races dynamic of Exserohulum turcium was investigated.Using routine technique,eighty-eight isolates of Exserohulum turcium,collected from 22 areas of Liaoning,Jilin and Heilongjiang provinces in 2010,was identified on different resistant genes（Ht1,Ht2,Ht3 and HtN）.The results showed that 14 races were identified among these fungal isolates,including 0,1,2,N,12,1N,23,2N,3N,12N,123N,123,23N and 13N.The physiological differentiation of E.turcicum in northeastern China was obvious.And the race infect the maize with all kinds of resistance genes was appeared.Among these races population,races 0 and 1 were predominant with occurrence frequency of 37.5% and 20.5%.The virulence frequencies against genes Ht1,Ht2,Ht3 and HtN was 45.5%,30.7%,15.9% and 23.7% respectively.The physiological race component and their inter-specific of E.turcicum variability in northeastern China became complex and new races were frequently found.The increasing epidemic of northern maize leaf blight in northeastern China was ascribed to the continuing occurrence of new races of the pathogen,the increasing virulence frequencies of such major races as 0 and 1,and the resistance losing of the cultivars.