引起油茶炭疽病胶孢炭疽菌种群遗传结构研究

Population genetic structure of Colletotrichum gloeosporioides causing anthracnose of Camellia oleifera in China

胶孢炭疽菌是引起油茶炭疽病的主要病原之一。目前对于该病原菌种群的遗传结构尚未见报道。研究病菌种群的遗传结构对制定科学的防治方法具有重要意义。本研究比较中国6个省12个不同地区的126个胶孢炭疽菌的ITS序列的差异,以期研究各不同群体的单倍体型多样性,不同地区群体之间的遗传关系,以及遗传距离与地理距离的线性关系。遗传分析发现,得到的126个胶孢炭疽菌样品ITS序列可定义为27种单倍体型。27种单倍体型中,一个主要的单倍体型(Haplotype12)含有78个样品,且基本上每个样品采集地都有分布。遗传分化指数(Fst)表明病菌不同地理种群间的遗传分化较大。AMOVA分析显示,种群间的遗传变异占总变异的6%,种群内部变异占总变异的94%。Mantel测试显示地理距离与遗传距离没有显著的线性关系。对所有地理种群病原菌ITS序列的核苷酸不配对进行分析,发现油茶炭疽病菌未经历过大规模的种群扩张过程。系统发育分析表明,来自不同地区的油茶炭疽病菌散乱的分布在系统树中。研究结果表明油茶炭疽病菌种群具有丰富的遗传多样性。

Anthracnose of Camellia oleifera is one of the most devastating diseases caused by Colletotrichum gloesporioides in China. Genetic structure of C. gloesporioides population is poorly understood. Studying the genetic structure of the population will help us to understand the evolution of the pathogen, and to design better strategies to control the disease. In this study, ITS-5.8S rDNA sequencing was used to analyze the genetic structure and genetic diversity of C. gloesporioides populations consisting of 126 strains isolated from 12 sites. Our genetic analysis identified a total of 27 ITS haplotypes, among which the major haplotype （Haplotype12） distributed in 78 specimens from almost all of the 12 sites. The genetic differentiation index, Fst, revealed sig- nificant genetic differentiation among C. gloesporioides populations obtained from different geographical loca- tions. AMOVA test showed that the levels of genetic differentiation were 6% and 94% among and within local populations, respectively. The Mantel test showed that the genetic distance was not linear -correlated with geo- graphical distance. Mismatch distribution analysis suggested there is no population expansion for C. gloespo- rioides. The results showed that C. gloesporioides natural population had rich genetic diversity.