同宗配合蜜环菌与欧美异宗配合蜜环菌狭义种的分子系统学关系

PHYLOGENETIC RELATIONSHIPS BETWEEN HOMOTHALLIC AND HETEROTHALLIC ARMILLARIA MELLEA

从亚洲、欧洲和北美收集18个蜜环菌狭义种菌株,PCR扩增其rDNA的IGS和ITS区域,用AluI、HaeIII、HinfI和TagI四种限制性内切酶进行酶切,同时用随机扩增微卫星(RAMS)多态性,对蜜环菌狭义种的进行了遗传多样性和分子系统学分析。结果蜜环菌狭义种的IGS和ITS-RFLP类型比以前报道的更多,亚洲、欧洲和北美菌株都具有比较明显的特征片段,通过ITS和IGS图谱可将三个大陆的菌株区分开,其中IGS-HinfI图谱能完全区分3个大陆的菌株。RFLP数据的系统学分析表明,该种存在明显的大陆遗传分化,亚、欧、北美的群体分属三个相互独立的进化系,北美群体IGS变异程度较小,ITS变异程度极高;而欧洲群体IGS的变异程度较大,多态性高,ITS变异程度非常小。RAMS系统分析表明,中国、日本和非洲的同宗配合蜜环菌属于一个系统发育系,该发育系同欧洲和北美的异宗配合种的两个发育系分属3个不同的独立进化分支。据此建议欧洲和北美的异宗配合蜜环菌应作为蜜环菌的两个亚种。

The 14 heterothallic isolates from Europe and North America, and 4 homothallic isolates from China and Japan of Armillaria mellea were used for phylogenetic analysis. The IGS and ITS of these isolates were amplified and digested by AluI, HaeIII, HinfI, TagI restriction enzymes. The result showed that the IGS-RFLP and ITS-RFLP patterns observed are quite complicated and the variability of the patterns is greater than that published before. The three continent isolates could be recognized by both IGS and ITS patterns, and every continent possessed a characteristic pattern of its own in the IGS-HinfI digestion. The dendrogram trees based on both IGS-RFLP and ITS-RFLP data indicated that there are three separate groups of A. mellea: Asian, European and North American and the ITS sequence was more variable than IGS for the North American group, and IGS sequence was more variable than ITS for the European group. The random amplified microsatellite (RAMS) experiments were carried out with the primers TCG, CGA, M13, GAAA and CT, respectively. Based upon the phylogenetic tree of RAMS results, these isolates were also separated into three clades, i.e. the European (EU), North American(NA), and Chinese(CH) geographical lineage. The Asian lineage consisted of homothallic isolates from Japan, and China. According to this result and the Phylogenetic Species Concept (PSC) of fungi, appeared recently, we suggest that these three groups should be considered as geographical subspecies.