Dissertation
Dissertation > Agricultural Sciences > Forestry > Forest Protection > Forest Pest and Disease Control > All kinds of tree pests and diseases and their prevention

Studies on Taxonomy of Rhytismatales on Castanopsis Plants and Its Sequence Analysis of Intraspecific Genetic Diversity of Hypoderma

Author LiuFang
Tutor LinYingRen
School Anhui Agricultural University
Course Forest Protection
Keywords Genetic diversity Rhytismatales Castanopsis Hypoderma rDNA-ITS sequences
CLC S763.7
Type Master's thesis
Year 2010
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Castanopsis plants in China are about 58 species, mainly distributed in the Yangtze river and its south warm regions. South of Anhui Province, Dabie Mountain area and Huangshan of our province are the distribution of the Castanopsis plants, and there are mainly Castanopsis eyrei, Castanopsis fargesii, Castanopsis fabri, Castanopsis sclerophylla and so on. Because of Castanopsis species have high economic value, scientific and effective disease prevention and control of the Castanopsis species are particularly important. In this thesis, systematics of part of specie of Rhytismataceae on Castanopsis was studied from morphology, development biology, ecology, distribution etc. with the techniques of modern mycology. Moreover nucleotide sequences of the internal transcribed spacer (ITS) region unclear rubosomal DNA were used to infer phylogenetic relationships of 12 Hypoderma strains. This results have important scientific significance on the taxonomy of the fungi and plant protection aspects.Samples of Rhytismataceae on Castanopsis were systematically studied according to the taxonomic principles Darker (1967), and also refer to Korf (1973), Cannon & Minter (1986), Kirk et al. (2001). 7 species among 2 genera (Lophodermium and Coccomyces) were identified. Enumerates as follows: Lophodermium unciforme, Lophodermium agathidis, Coccomyces limitatus, Coccomyces occultus, Coccomyces radiatus, Lophodermium minor, Coccomyces mucronatus. Among them Lophodermium unciforme was a new specie to be published, type specimens of the new specie is preserved in the Forest Protection Laboratory of Anhui Agricultural University, (AAUFP), hefei, China. The six known species were complementary studied, to perfect their morphological characteristics. Morphological and anatomical characteristics of the description and illustration, host and habitat records, and their similar groups, parasites, and pathogenicity are discussed. And according to the main morphological characteristics, dichotomous keys to these species were complied.In this thesis, Fresh materials of Hypoderma rubi collected from Anhui Province were isolated by tissue isolation technique, and 12 pure strains were obtained. DNA of all the strains were extracted from the dry mycelia, rDNA-ITS regions were amplified by PCR and then sequenced. The sequencing results of rDNA-ITS regions were to be registered in GenBank (GU138743, GU138751, GU138753, GU138749, GU138735, GU138750, GU138744, GU138746, GU138741, GU138736, GU138738, GU138739). The ITS sequence analysis results showed that the length range of ITS sequences of H. rubi was from 443bp to 456bp, and the percentage of G+C contents of the ITS sequences varied from 48.7% to 51.5%. There were obvious variations in the ITS sequences of different strains and showed abundant genetic diversity among them. A phylogenetic tree was constructed by neighbour-joining method using MEGA4.1. The results indicated that the intraspecific genetic diversity of H. rubi was related to hosts obviously, and strains from woody plants and herbaceous plants probably were two distant relationship groups. In addition, the intraspecific genetic differences of H. rubi were independent of parasitic sites and sample collection area. According to statistics, the strains of the host plants involved in the angiosperms and gymnosperms. For example, Aceraceae, Anacardiaceae, Araliaceae, Asteraceae, Fagaceae, Gramineae and other 21 families, 30 genera and 32 species (varieties). Therefore, Hypoderma rubi in collaboration with the host of the long-term evolution, will produce a richer variation of groups, will be a question worth exploring.

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