新疆棉花枯萎病菌异核体及其不同表型分离子核DNA的差异

NUCLEAR DNA DIFFERENCE BETWEEN A HETEROKARYON AND ITS PHENOTYPIC SEGREGANTS OF FUSARIUM OXYSPORUM F.SP.VASINFECTUM ISOLATED FROM XINJIANG,CHINA

为探索丝状真菌异核体的产生机制,从新疆地区患枯萎病的棉杆中分离出棉花枯萎病菌Fusariumoxysporumf.sp.vasinfectum异核体菌株X515,并自其菌落出现的不同角变处分离出三个不同表型的分离子,X515-Ⅰ、X515-Ⅱ和X515-Ⅲ。选用200种随机引物对它们进行核DNA的RAPD分析,只在OPB-16引物对致病力强的分离子X515-Ⅰ核DNA的PCR扩增产物中出现了一条354bp的差异片段,其部分碱基序列与Fusariumoxysporumf.sp.lycopersici的短散布序列(Foxy)末端序列的相似性达88%。本研究结果提示,随着所采用引物数量的增加,可有望找出异核体及其不同分离子之间核DNA的差异,为最终阐明异核体形成的机制提供线索。

A heterokaryon (X515) of Fusarium oxysporum f.sp.vasinfectum was isolated from the diseased cotton stem in Xinjiang Autonomous Region, China. Three phenotypic segregants (X515-I, X515-II and X515-III) were separated from the sectors on colony of the heterokaryon. They have remarkable differences on color of colony, morphology of hypha and pathogenicity. RAPD analysis on the nuclear genome of the heterokaryon and its three segregants by using 200 arbitrary primers. Only one primer (OPB 16) could give an extra DNA band with 354bp which was the PCR product when using X515-I as the template. The special fragment was sequenced and compared with the related DNA sequences in GenBank. The region from 136 to 178 shared 88% similarity with the 3?terminal end of Foxy, a short interspersed nuclear element in Fusarium oxysporum f.sp.lycopersici.This result indicated that increasing the number of primers of RAPD could hopefully manifest the difference of nuclear DNA between the heterokaryon and its segregants, and finally to reveal the cause of fungal heterokaryon formation.