由部分核糖体RNA序列确定的绿僵菌属种系统发育关系

本研究应用特异寡聚核苷酸引物和双脱氧核苷酸终止法测定绿僵菌Metarhizium不同种的部分rRNA序列。这些序列分别选自小亚基(18S)和大亚基(25S)rRNA上的不同区域。校排的不同序列用于计算核苷酸的差异。绿僵菌的系统发育关系采用最大可能性(Maximum-Likelihood)方法分析。所有的分类单元聚类成二个分支。在产生圆柱状瓶形小梗的种中,M.anisopliae var.anisopliae,M.anisopliae var.majus,M.brunneum(NRRL1944),M.guizhouense,M.pingshaense和未知种M.sp.2组成一个密切相关的群组,而M.anisopliae(ACCC 30104)位于这群组之外。在产生棍棒状瓶形小梗的种中,M.album,M.cylindrosporae和M.flavoviride互相独立成支。实验结果不支持Metarhizium只能区分为M.anisopliae和M.flavoviride二个种的分类观点。文中还讨论了经典分类标准的系统发育价值。

PHYLOGENY OF METARHIZIUM SPECIES AS DETER MINED BY PARTIAL RIBOSOMAL RNA SEQUENCES

This study used dideoxy nucleotide chain termination method and specific oligonucleotide primers to determine partial sequences of selected regions from small (18S) and large (25S) subunit rRNAs of species of Metarhizium. The aligned sequences were calculated for nucleotide differences. Phylogenetic relationships among species were analyzed by the maximum-likelihood procedure. The taxa cluster into two main groups: among cylindrical conidiogenous-cell forming species, M. anisopli-ae var. anisopliae, M. anlsopliae var. majus, M. brunneum (NRRL 1944), M. guiz-houense, M. pingshaense and unknown species M. sp. 2 constitute a closely related group distinguishable from M. anisopliae (ACCC 30104); of the clavate conidiogenous-cell forming species, M. album, M. cylindrosporae and M. flavoviride are well separated from one another. Our results do not support classification schemes that accept only M. anisopliae and M. jlavoviride in Metarhizium. The phylogenetic value of taxonomical criteria is discussed.