云南虫生真菌粉棒束孢遗传分化研究

Genetic differentiation of an entomogenous fungus Isaria farinosa in Yunnan, China

对云南粉棒束孢8个当地居群和蝙蝠蛾拟青霉2个当地居群进行ITS测序和RAPD扩增分析,结合Gen Bank中相关序列,对粉棒束孢开展遗传多样性、居群遗传结构及其种内分化研究。共获得大范围内地理距离远的6个居群共97条粉棒束孢ITS序列,共有33种单倍型,单倍型多样性Hd=0.546和总核苷酸多样性Pi=0.00276,显示粉棒束孢在物种水平上遗传多样性较低。云南粉棒束孢共37条序列,有14种单倍型(10种为云南特有),具有较高单倍型多样性和核苷酸多样性(Hd=0.659,Pi=0.00274);单倍型聚类和网状分支分析表明云南粉棒束孢单倍型类型丰富,遗传多样性高,暗示云南为粉棒束孢多样性分布中心之一。ITS序列分析表明,云南当地居群间遗传分化系数Fst=51.95%;RAPD分析表明,居群间遗传分化系数Gst=0.5547,基因流Nm=0.4014;说明云南当地居群粉棒束孢分化剧烈。居群遗传距离与地理距离相关性研究表明,粉棒束孢居群遗传距离与地理距离无明显相关。中性检验和失配分析表明粉棒束孢经历过近期居群扩张。结合单倍型聚类和网状分支分析,表明Hap 19为扩张建群单倍型,但原始祖先单倍型(Hap 1)依然是粉棒束孢居群中最优势单倍型(频率为48.45%),表明粉棒束孢并不存在明显的因地理原因造成的生殖隔离。值得重视的是,通过ITS单倍型和RAPD分析,支持将蝙蝠蛾拟青霉作为粉棒束孢异名处理。

In order to detect the genetic diversity, population genetic structure and intraspecific differentiation of Isaria farinosa, the ITS sequencing and RAPD amplification were conducted in 8 local populations of Isaria farinosa and 2 local populations of Paecilomyces hepiali in Yunnan. Together with the ITS sequences in Gen Bank, a total of 97 ITS sequences of I. farinosa were obtained in the 6 populations from widely separated geographical locations. The 33 haplotypes were discovered in the populations sampled of I. farinosa. The haplotype（gene） diversity was Hd=0.546 and nucleotide diversity was Pi=0.00276, showing lower degree of genetic diversity at the species level. A total of 14 haplotypes were found in the local populations of Yunnan, and 10 of them were not found elsewhere. The haplotypes＇ clustering and network analyses demonstrated a richer genetic diversity of I. farinosa in Yunnan. The coefficient of genetic differentiation from ITS sequence analysis was Fst=51.95% among the 8 local populations in Yunnan. The gene flow from RAPD analysis was Nm=0.4014. It was shown that a great genetic differentiation was presented in the local populations of I. farinosa in Yunnan. The results of mantel tests revealed that there were no significant correlations between the average genetic distance and the geographic distance among geographically distant or local populations. Neutrality test and mismatch analysis revealed that the species went through a recent population expansion. By combining the results from haplotypes clustering and network analysis, it was inferred that the haplotype（Hap 19） might be the founder. However, the original ancestor haplotype（Hap 1） also had absolute predominance. These results indicated that I. farinosa did not experience an obvious reproductive isolation. In addition, P. hepiali could be considered the synonym of I. farinosa based on ITS haplotypes and RPAD analyses.