基于多基因序列分析对尖孢镰孢菌古巴专化型（香蕉枯萎病菌）生理小种的鉴定

由尖孢镰孢菌古巴专化型Fusarium oxysporum f. sp. cubense, Foc引起的香蕉枯萎病是香蕉生产上的毁灭性病害，自1996年以来已对我国华南地区香蕉生产造成了严重危害。传统上香蕉枯萎病菌生理小种的鉴定主要采用人工接种鉴别寄主尔后测定病菌致病性的方法，但实验周期长，且受季节影响。以来自澳大利亚的香蕉枯萎病菌生理小种1号（BW1）、2号（Race 2）、3号（Race 3）以及亚热带4号（BW4）为对照，对分离自我国华南地区主要香蕉产区（广东、广西、海南、福建等省区）的14株香蕉枯萎病菌的单孢菌株进行致病性测定，并结合热带4号小种（TR4）和亚热带4号小种（ST4）的分子特异检测方法，确定其生理小种类型；同时，利用ITS、TEF-1α、IGS、histone H3、β-tubulin等 5个主要用于镰孢菌系统发育学研究的基因，研究不同地区不同来源的Foc菌株之间的亲缘关系及其与非病原尖孢镰孢菌的关系，并评价这5个基因在香蕉枯萎病菌生理小种鉴定上的应用价值。研究结果表明：（1）来源于我国华南地区的4号小种主要为热带4号小种；（2）TEF-1α、IGS、histone H3等3个基因片段能够将Foc中不同生理小种的菌株划分成不同的系统发育谱系，与致病性测定的结果具有对应关系，也能较好地反映尖孢镰孢菌种内菌株的亲缘关系，可用于香蕉枯萎病菌生理小种鉴定；（3）我国Foc 1号生理小种的遗传多样性高于4号生理小种，Foc 1号生理小种的菌系与来自香蕉果实上的非病原尖孢镰孢菌的亲缘关系比其与Foc 4号生理小种的菌系的亲缘关系更近。

The identification on race of Fusarium oxysporum f. sp. cubense based on multi-gene sequence analysis

Fusarium wilt of banana caused by F. oxysporum f. sp. cubense (Foc) is one of the most widespread and destructive plant diseases in the world. It has been a serious problem in many banana growing areas in South China since 1996. Traditionally, pathogenicity test method was used to determine physiological races of plant pathogens, but it is time consuming and unstable. The current study was designed to determine races of F. oxysporum f. sp. cubense by applying molecular markers instead of traditionally artificial inoculation. Four Foc isolates from Australia representing race 1 (BW1), race 2 (Race 2), race 3 (Race 3) and subtropical race 4 (BW4) were used for comparison. The physiological races of 14 pathogenic strains isolated in South China (Guangdong, Guangxi, Hainan, and Fujian provinces) were tested by artificial inoculation, and reconfirmed by molecular specific markers. Five loci DNA sequences including ITS, TEF-1α, IGS, histone H3, and β-tubulin were used to investigate the genetic relationships among the Foc strains, and the genetic relationships between Foc and nonpathogenic strains. The application of these five DNA sequences was evaluated. The results showed that: (i) Foc race 4 strains recovered from South China were TR4; (ii) TEF-1α, IGS, and Histone H3 showed well resolution within lineages of Foc, corresponding with the pathogenicity test results, so these three DNA loci could be used for physiological race identification; (iii) genetic diversity in race 1 was greater than that in race 4, and lineages identified as race 1 were phylogenetically closer to nonpathogenic lineages than to race 4.