Studies on Taxonomy, Cultivation and Molecular Phylogenetics Base on rDNA-ITS Sequences of Coccomyces from Central China
|School||Anhui Agricultural University|
|Keywords||Coccomyces Taxonomy Culture characteristics rDNA-ITS sequences Central China|
Taxonomy and diversity of Coccomyces were systematically studied from HubeiShennongjia forest region, Hunan Zhangjiajie scenic area and Jiangxi Sanqing mountainscenic area with the advanced fungal classification system and poly-charactercomprehensive classification methods which are according to the characters of morphology,individual development, ecology, geographical distribution and cultural characteristics etc.Besides, different strains of Coccomyces are seclected for DNA extraction，DNA-ITSsequences of these pure strains through amplifying and sequencing are obtained finally.Using maximum parsimony method, a phylogenetic tree was constructed from13newlysubmitted DNA-ITS sequences of Coccomyces and other2related sequences in GenBankand Phenotypic character by PAUP*4.0b4a. The relationships and genetic diversity ofCoccomyces in interspecies and intraspecies were discussed.Specimens collections from the Central China Region in person and the Herbarium ofForest Fungi of Anhui Agricultural University (AAUF) were examined and classifiedbased on the taxonoic principles of Darker（1967）、Cannon&Minter（1986）、Kirk et al.(2008). Seven species of Coccomyces were studied, including Coccomyces hubeiensis,Coccomyces jiangxiensis, Coccomyces sinensi, Coccomyces delta, Coccomyces dentatus,Coccomyces mucronatus, Coccomyces huangshanensis. Among them, Coccomyceshubeiensis and Coccomyces jiangxiensis are described as2new species. Morphologicalcharacteristics descriptions, illustrated, hosts and geographic distribution were recordedand disscussed, as well as a Coccomyces dichotomous key from central China werecompiled for all species.Cultural characteristics of three Coccomyces strains which live on different hosts werestudied on different media. The shape, growing rate, color, morphology, conditions of aerialhyphae and latent hyphae, diameter, secreting pigments or not and producing conidiomata,black shell and zone lines or not of each pure cultures colonies were observed and recordedperiodically. Meanwhile, colorful photographs of cultural characteristics were also takenperiodically. Study of cultural characteristics of several species within this genus could laythe foundation for further study of molecular systematics afterwards.A phylogenetic tree was constrcuted based on fifteen rDNA-ITS sequences ofCoccomyces and Hypoderma stephanandrae (GU138753*) was selected as outgroup, thendeveloped into two isolated clades (I&II). Three conclusions were drawed from theanalysis of the phylogenetic tree. Firstly, origin have great impact on Intraspecific genetic diversity, the strains which from the same origin are clustered together preferentially, andhave a closer relationship. Secondly, different host species have more important influenceon genetic diversity of intraspecies of Coccomyces. Thirdly, position of embedding, lipsand excipulum have or not, the shape of asci and paraphyses have important taxonomysignificance for Coccomyces in the species level. G+C contents content of15strains wereanalysed by the mode of MEGA3.1, the results showed that the length of ITS sequences ofCoccomyces is436bp—457bp, and the G+C contents of the ITS sequences are48.0%—51.6%, both intraspecific strains and interspecific strains have a marked change in the G+Ccontent and length of ITS sequences. This shows that host and origin are closely related tothe genetic variation and diversity of interspecific and intraspecific of Coccomyces.