ABSTRACT

The hyperdiverse genus Trichoderma is one of most useful groups of microbes for a number of human activities, and their accurate identification is crucial. The structural simplicity and lack of distinctive phenotypic variation in this group enable the use of DNA-based species delimitation methods in combination with phylogenies (and morphology when feasible) to establish well-supported boundaries among species. Our study employed a multilocus phylogeny and four DNA-based methods (automated barcode gap discovery [ABGD], statistical parsimony [SPN], generalized mixed Yule coalescent [GMYC], and Bayesian phylogenetics and phylogeography [BPP]) for four molecular markers (acl1, act, rpb2, and tef1) to delimit species of two lineages of Trichoderma. Although incongruence among these methods was observed in our analyses, the genetic distance (ABGD) and coalescence (BPP) methods and the multilocus phylogeny strongly supported and confirmed recognition of 108 and 39 different species in the Harzianum and Longibrachiatum lineages, including three new species associated with cacao farms in northern Peru, namely, T.awajun, sp. nov., T. jaklitschii, sp. nov., and T. peruvianum, sp. nov. Morphological distinctions between the new species and their close relatives are primarily related to growth rates, colony appearance, and size of phialides and conidia. This study confirmed that an integrative approach (DNA-based methods, multilocus phylogeny, and phenotype) is more likely to reliably verify supported species boundaries in Trichoderma.

摘要

高度多样化的木霉属是对许多人类活动最有用的微生物群之一，它们的准确识别至关重要。该组中的结构简单和缺乏独特的表型变异使基于 DNA 的物种定界方法与系统发育（以及可行时的形态学）相结合，可以在物种之间建立良好支持的边界。我们的研究采用多位点系统发育和四种基于 DNA 的方法（自动条形码间隙发现 [ABGD]、统计简约 [SPN]、广义混合 Yule 聚结 [GMYC] 和贝叶斯系统发育和系统地理学 [BPP]）用于四种分子标记 ( acl1 , act, rpb2和tef1 ) 来划分木霉两个谱系的物种. 尽管在我们的分析中观察到这些方法之间的不一致，但遗传距离 (ABGD) 和合并 (BPP) 方法以及多位点系统发育强烈支持并证实了对 Harzianum 和 Longibrachiatum 谱系中 108 和 39 种不同物种的识别，包括三个相关的新物种与秘鲁北部的可可农场合作，即T. awajun , sp. nov., T. jaklitschii , sp. 11 月和T. peruvianum，sp。十一月 新物种与其近亲之间的形态差异主要与生长速度、菌落外观以及小孢子和分生孢子的大小有关。该研究证实，综合方法（基于 DNA 的方法、多位点系统发育和表型）更有可能可靠地验证木霉属中支持的物种边界。