Studies On Taxonomy Of Coccomyces On Evergreen Broad-leaved Trees From Huangshan Scenic Spot And Analysis Of Interspecific Genetic Diversity Of The Genus

Huangshan scenic spot located in southern Anhui Provience is the main landscapearea of our country. The complex terrain, mild temperature and plentiful rainfall make itsuitable for reproduction of numerous plants, Coccomyces species are widely distributed aswell. Members of Coccomyces which collected from the evergreen broad-leaved trees ofHuangshan scenic spot were systematically studied with the most advanced poly-characterintegrated taxonomy method focused on the characters of morphology, developmentalbiology, ecology, and distribution, etc. Moreover, the method of the nucleotide sequencesof internal transcribed spacer (ITS) were used to infer phylogenetic relationships of the18Coccomyces strains. Results determined the importance of some morphological charactersand the category diversity of hosts on the classification of fungal species level.Relationships and genetic diversity of the interspecific strains of Coccomyces were furtherconfirmed.Specimens of Coccomyces on the evergreen broad-leaved trees collected fromHuangshan scenic spot and owned by the Herbarium of Forest Fungi of Anhui AgriculturalUniversity (AAUF) were classified and identified according to the taxonoic principles ofSherwood(1980), Johnston(1986), Spooner(1990) and Kirk et al.(2008).13species wereindentified, including Coccomyces cyclobalanopsis, C. delta, C. huangshanensis, C.illiciicola, C. leptideus, C. limitatus, C. magnus, C. minimus, C. mucronatus, C.multangularis, C. occultus, C. sinensis, C. symploci. Among them C. minimus was a newspecies to be published, latin diagnoses were given as well. Morphological characteristics,habits, hosts and discussions were provided for each species. Dichotomous key to thesespecies were complied.In this thesis, fresh materials of Coccomyces collected from Huangshan scenic spot,Tiantangzhai National Forest Park and Wanfoshan National Forest Park were isolated andcultivated by tissue isolation technique, and13pure strains were obtained. DNA of all thestrains were extracted and detected, rDNA-ITS regions were amplified by PCR and thensequenced. G+C content of18strains were analysed by the method of MEGA4.1. Thestatistical results indicated that the length of ITS sequences of each Coccomyces was rangefrom436bp to457bp, and the G+C contents of the ITS sequences varied from48.0%to51.6%, the length of ITS sequences and G+C content of intraspecific strains are lowervariable than that of interspecific strains. This shows that interspecific genetic diversity ismore abundant than of intraspecific. A phylogenetic tree of18strains was constructed by maximum parsimony method (MP) performed with PAUP*4.0b4a, and developed into twoisolated clades (I and II), which were consistent with the classification based onmorphological phenotypic traits. The result also shows that variety of hosts had a greatimpact on interspecific genetic variation which was not significantly associated with originby analysis the difference of parsimonious tree combined with morphology. Therefore, ITSsequence analysis can be an effective method to distinguish related species of Coccomyces.