Molecular Phylogenetics And Convergent Evolution Study Of Aquatic Hyphomycetes

Aquatic hyphomycetes are a group of filamentous fungi, which can produce sigmoid and tetraradiate forms conidiospores in the freshwater. They perched on the foreign organic matter which is mainly all kinds of dead plant tissue in water. These fungi are referable to anamorph of ascomycotas and basidiomycota. Anamorph of fungi grow faster and produce more spores than telemorph. So, the anamorph has more potential on the ecological function and industrial application. The aquatic hyphomycetes linked with their telemorphs are less than10%of described, so their identification and classification are largely based on anamorph characteristics, and the classification system relying on the anamorph characteristics can’t reflect genetic relationship of each other. Aquatic hyphomycetes were in the water environment for long time, and convergent evolution exsit because they must adapt to the water environment. So, there are lots of errors in the classification system that rely on morphological characteristics of spores, which was reflected throuth paraphyletic of part genera. It is very important to study the molecular phylogenetics of aquatic hyphomycetes, but this work has not been carried systematically.On this basis, four gene fragments (ITS,18S,28S, TEF) were combined and analysed, which were from105strains of60genera hyphomycetes isolated from leves of freshwater plant, and the following research results are obtained:1. The105hyphomycetes of60genera, about102species, belong to ascomycota and basidiomycota. They are distributed in five classes in the ascomycota: Sordariomycetes, Dothideomycetes, Leotiomycetes, Orbiliomycetes and Eurotiomycetes. And the strains in basidiomycota are distributed in Agaricomycetes.2. The systematics positions of17anamorph genera were confirmed firstly by compared to related sequences that got by ITS BLAST from NCBI: Pseudoanguillospora, Trichomatomyces, Solosympodiella, Ardhachandra, Corynesporella, Pseudobeltrania, Selenosporopsis, Umbellidion, Matsushimomyces, Aschizotrichum, Chaetopsis, Haplobasidion, Pleurotheciopsis, Spermospora, Brachydesmiella, Uncispora and Seychellomyces. 3.7genera, including Mammaria, Helicomyces, Haplobasidion, Triscelophorus, Uncispora, Seychellomyces and Trichocladium, were connected to their teleomorphs by analysis combined phylogenetic study and ITS similariy.4. By combining multi-genes sequence analysis, it was found that2morphologic species of Diplosporium were distributed in two families of Hypocreales. Two species of Helicomyces were distributed in Hypocreales and Xylariales respectively. And also, two strains of Mammaria were distributed in Hypocreales and Xylariales respectively. The results showed polyphyly of the three morphologic genera preliminary.5. Molecular phylogenetics of13typical aquatic hyphomycetes tetraradiate spores were studyed. Result shows that all the strains were distributed into three classes: Sordariomycetes, Leotiomycetes and othideomycetes. Convergent evolution of aquatic hyphomycetes was confirmed, that is to say, fungi from very different ancestors can produce similar spores.