National Institute of Technology and Evaluation, Kisarazu, Chiba, Japan.
Mycologia. 2012 Sep-Oct;104(5):1109-20. doi: 10.3852/11-253. Epub 2012 Apr 11.
Four isolates tentatively identified as Pseudaegerita matsushimae on the basis of the morphology of bulbil-like propagules were collected from substrates submerged in water in Thailand and Japan. In culture studies the two Thai isolates were found to produce phialoconidia on conidiogenous cells and phialoconidiophores whose morphology was similar to that of Trichoderma. Phylogenetic analysis based on D1/D2 regions of LSU rDNA sequences showed that the four isolates were nested in Hypocrea/Trichoderma (Hypocreales) while P. corticalis, the type species of Pseudaegerita, belongs to Hyaloscypha (Helotiales). Preliminary analysis by ISTH Web tools based on 5.8S-ITS rDNA and phylogenetic analysis based on rpb2 and tef1-int4 genes showed that the isolates have specific sequences of Trichoderma (anchors 1-5) and belong to the Hamatum clade but they grouped apart from any known species of Trichoderma. The sequences of the tef1-int4 gene, which were amplified from the authentic specimen of P. matsushimae (IMI 266915), also showed that it belongs to the Hamatum clade closely clustering with T. yunnanense but separate from our four isolates. The morphology of P. matsushimae (IMI 266915), especially the sizes of phialides and phialoconidia, were different from T. yunnanense. Thus, we conclude that IMI 266915 and our isolates are to be assigned to two different species in the Hamatum clade of Trichoderma, although both species have similar morphology of bulbils and phialoconidia. Morphology and molecular data revealed that P. matsushimae should be assigned to the genus Trichoderma as T. matsushimae and the Thai and Japanese isolates are placed in T. aeroaquaticum sp. nov. This finding supports the interpretation that aero-aquatic fungi have evolved from terrestrial fungi. We assume that these fungi probably were derived from typically soil-inhabiting species of Trichoderma; an adaptation to aquatic environments is shown by formation of bulbil-like propagules floating on water.
基于类似块茎状繁殖体的形态，从泰国和日本浸没在水中的基质中分离到四个暂定鉴定为 Pseudaegerita matsushimae 的菌株。在培养研究中，发现两个泰国分离株在产孢细胞和瓶梗上产生瓶梗分生孢子，其形态与 Trichoderma 相似。基于 LSU rDNA 序列的 D1/D2 区的系统发育分析表明，这四个分离株嵌套在 Hypocrea/Trichoderma（Hypocreales）中，而 P. corticalis，即 Pseudaegerita 的模式种，属于 Hyaloscypha（Helotiales）。基于 5.8S-ITS rDNA 的 ISTH Web 工具的初步分析和基于 rpb2 和 tef1-int4 基因的系统发育分析表明，这些分离株具有特定的 Trichoderma 序列（锚 1-5），属于 Hamatum 分支，但与任何已知的 Trichoderma 物种分开。从真正的 P. matsushimae（IMI 266915）标本中扩增的 tef1-int4 基因序列也表明它属于 Hamatum 分支，与 T. yunnanense 紧密聚类，但与我们的四个分离株分开。P. matsushimae（IMI 266915）的形态，特别是瓶梗和瓶梗分生孢子的大小，与 T. yunnanense 不同。因此，我们得出结论，尽管两种形态都具有相似的块茎状繁殖体和瓶梗分生孢子，但 IMI 266915 和我们的分离株应被分配到 Trichoderma 的 Hamatum 分支中的两个不同种。形态学和分子数据表明，P. matsushimae 应被归类为 Trichoderma 属中的 T. matsushimae，而泰国和日本的分离株被归类为 T. aeroaquaticum sp. nov. 这一发现支持了这样的解释，即气生真菌是从陆生真菌进化而来的。我们假设这些真菌可能源自典型的土壤栖息的 Trichoderma 物种；通过形成漂浮在水上的类似块茎状的繁殖体来适应水生环境。
