大蕉枯萎病病原菌鉴定及TEF-1α序列分析

近年来,大蕉枯萎病在广东省东莞市发生严重,为了有效控制病害发生蔓延,生产上急需明确大蕉枯萎病的病原。本研究收集了我国华南地区的12株大蕉枯萎病病原菌及19株包括1号及4号生理小种的单孢菌株,以来源于澳大利亚的1号、2号、3号和亚热带4号生理小种以及4株非病原尖孢镰孢菌作对照,通过病原菌形态鉴定、致病性测定、4号小种(Foc 4)及热带4号小种(TR4)的分子特异检测、以及基于翻译延伸因子(TEF-1α)序列的系统发育分析,对大蕉枯萎病病原菌进行鉴定。同时,对我国华南地区不同来源的香蕉枯萎病病原菌的遗传发育关系及致病性分化情况进行了研究。结果表明:(1)引起大蕉枯萎病的病原菌主要是1号生理小种或者是与1号生理小种亲缘关系较近的一个新的系统发育谱系,该谱系可能为1号生理小种变异演化而来;(2)大蕉枯萎病病原菌对大蕉和粉蕉都有较强的致病力,但不能侵染香蕉;我国的1号小种存在一定的分化,其中有一个类群只能感染粉蕉,另一个类群既能感染粉蕉也能感染大蕉;(3)大蕉与粉蕉枯萎病的病原菌在致病性及遗传发育关系上都存在一定的交叉和分化。

Identification and TEF-1α sequence analysis of Fusarium wilt pathogens from Dajiao

In recent years, Fusarium wilt of Dajiao has been becoming one of the most damaging diseases in Dongguan, Guangdong Province. In order to control the spread of this disease effectively, it is necessary to investigate the causal agent of Fusarium wilt of Dajiao. However, few of studies have focused on this new disease so far. In this study, a total of 31 Foc (Fusarium oxysporum f. sp. cubense)isolates from diseased tissues of banana plants were analyzed, including 12 Foc isolates from diseased Dajiao and 4 standard isolates from Australia which represent race 1, race 2, race 3 and subtropical race 4, respectively. What’s more, four non-pathogenic F. oxysporum isolates were also involved in the study for comparison. Pathogen of Dajiao was identified through pathogenicity tests, morphological studies, molecular specific detection for race 4 and tropical race 4, and phylogenetic analysis based on TEF-1α sequences. In addition, genetic relationship and pathogenic differentiation among the Foc strains were also investigated. The results showed that: (i) The wilt pathogen of Dajiao is Foc race 1 or a new lineage within Foc which is genetically close to race 1, and might be evolved from Foc race 1. (ii) The pathogen can seriously infect both Dajiao and Fenjiao, but can not infect Cavendish. Genetic differentiation was present among Chinese Foc race 1 isolates, and there were two subgroups in Chinese Foc race 1 isolates (one could only infect Fenjiao (Musa ABB Fenjiao), the other could infect both Dajiao and Fenjiao). (iii) The evolutionary relationship of Foc is complex. Both the pathogenicity tests and molecular phylogeny results showed that there may be some overlap and differentiation within the pathogens of Dajiao and Fenjiao.