Genetic diversity, reproductive biology, and speciation in the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin
Genetic diversity, reproductive biology, and speciation in the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin
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DOI：
10.1139/g06-004
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发表时间：
2006-05-01
期刊：
影响因子：
3.1
通讯作者：
Padmavathi, J.
中科院分区：
文献类型：
--
作者：
Devi, K. Uma;Reineke, A.;Padmavathi, J.
球孢白僵菌是一种用于生物防治多种昆虫的有丝分裂真菌，被认为是由不同的遗传谱系组成的“物种复合体”。由于主要是无性繁殖，交配测试不能用于划分该物种复合体中的物种。基因测试提供了一种在分离株中鉴定物种的间接方法。为此，我们对球孢白僵菌的2个亚样进行了分子遗传分析，其中1个亚样代表了世界范围内的样品，另一个亚样来自一个局部的流行性种群。对AFLP(扩增片段长度多态)和SSCP(单链构象多态)产生的DNA标记和3个基因(rRNA大小亚基和β-微管蛋白)不同等位基因形式的核苷酸序列数据进行了评价。来自全球样本的球孢杆菌分离物有11%的总体相似性，没有紧密聚集的群。根据该样本的AFLP和SSCP数据生成的系统发育树将不同的分离物分解为不同的系统发育谱系。在球孢白僵菌的流行性种群中，多位点检测中等位基因的随机关联和3个基因谱系之间缺乏系统发育的一致性证明了重组的普遍存在。因此，世界范围内的球孢杆菌样本表现出以克隆为主的结构，这暗示着物种差异导致了隐蔽的物种形成，重组在共享密切生态位的菌株之间是惯常的。
Beauveria bassiana, a mitosporic fungus used for the biological control of many insect species, is recognized as a "species complex" comprising genetically diverse lineages. Being predominantly asexual, mating tests cannot be applied to delimit species in this species complex. Genetic tests offer an indirect means of identifying species among isolates. To this end, molecular genetic analysis of a sample of B. bassiana isolates with 2 subsamples, 1 representing a worldwide collection and another from a localized epizootic population was carried out. DNA markers generated through AFLPs (amplified fragment length polymorphisms) and SSCPs (single-strand conformation poly morphisms) and nucleotide sequence data of different allelic forms of 3 genes (large and small subunits of rRNA and beta-tubulin) were evaluated. The B. bassiana isolates from the worldwide sample showed 11% overall similarity and no closely clustered groups. Phylogenetic trees generated from the AFLP and SSCP data of this sample resolved the different isolates into distinct phylogenetic lineages. In the epizootic B. bassiana population, prevalence of recombination was evident from random association of alleles in multilocus tests and lack of phylogenetic concordance among 3 gene genealogies. Thus, the worldwide sample of B. bassiana exhibits a predominantly clonal structure, hinting at species divergence leading to cryptic speciation with recombination being customary among isolates sharing a close ecological niche.