Taxonomic Studies Of Dematiaceous Hyphomycetes From Soil Of Middle-southern Subtropical And Tropical Zones In China

Soil fungi are those which have part of or whole life cycle either in or directly associated with soil environment. Their roles in soil is extremely complex and fundamental to soil ecosystem. It is a group of organisms with an immense diversity. The species of Fungi Imperfecti are the most abundant in the soil, of which dematiaceous Hyphomycetes account for more than one half. Our country spans cold-warm temperate zone, variable zone, subtropical and tropical zones. Therefore, soil and vegetation types are very plentiful. Soil as a complex ecosystem, may contains abundant of fungi resources. This study is a part of a whole set of diversity survey of dematiaceous Hyphomycetes in the soil of China. It was aimed at ascertaining the diversity at genus and species level, the survival state, distribution and ecological significance of soil dematiaceous hyphomycetes in the middle-eastern subtropical and tropical zones of China as the the basis of further studies and utilizations of fungus resouces.1. The diversity survey of soil dematiaceous hyphomycetes Approximately 340 soil samples from many representative sites selected in Hunan, Guangxi, Hainan Provinces, the Guangxi Zhuang Autonomous Region and Chongqing City were From which, 700 fungal isolates were isolated using soil plate method and dilution plates methods. Based on careful identification, 101 species belonging to 45 genera of dematiaceous hyphomycetes were found.Among them, 17 are new species: Codinaea curvospora, Coremiella chongqingensis, Cirrenalia hunanella, Doratomyces cylindrospora, Gliomastix kurrajongospora, Gliomastix tshawytschae, Graphium tintospora, Humicola guangxiensis, Humicola brachypodi, Pseudobotrytis terrestris, Phialomyces microsporus, Rhinocladiella fusoidea, Scolecobasidium ellipsoideum, Scolecobasidium hainanensis, Scolecobasidium anisomerospora, Strchybotrys lightospora and Taeniolella hunanensis。Eighteen species are newly recorded to China, they are: Acrophialophora fusispora (Saksena) M. B. Ellis, Beltraniopsis esenbeckiae Batista & Bezerra, Chloridium viresceens (Pers. ex Pers.) W. Gams & Hol.-Jech. var. virescens (Pers.) W. Gams & Hol.-Jech., Curvularia borreriae(Viegas)M. B. Ellis, Curvularia brachyspora Boedijn, Domingoella asterinarum Petrak & Ciferri, Embellisia annulata de Hoog, Seigle-Murandi, et Eriksson, Gliomastix murorum (Corda) S. Hughes var. polychroma (van Beyma) Dickinson, Gliomastix murorum (Corda) S. Hughes var. felina (Marchal) S.Hughes, Nodulisporium hinnuleum G. Smith, Phaeoisaria clematidis S. Hughes, Phialophora geniculata J. H. Emden van, Stachybotrys dichroa Grove, Strachybotrys nephrospora Hanf., Stachybotrys zeae G. Morgan-Jones & G. W. Rarr. Jr., Scytalidium lignicola Presented, Torula caligans (Batista & Upadhyay) M. B. Ellis and Veronaea parvispora M. B. Ellis。Eight newly recorded genera to China are Beltraniopsis Batista & Bezerra, Chloridium Link ex Fr., Codinaea Marie, Coremiella Bubák & Krieger, Domingoella Petrak & Ciferri, Nodulisporium Preuss, Phaeoisaria H?hnel and Rhinocladiella Nannfeldt。Three new combinations are Arthrinium haricotospora (Sacc.) Y. L. Zhang & T. Y. Zhang, Gliomastix verruculosaospora (H?hnel) Y. L. Zhang & T. Y. Zhang, Myrothecium curvospora (Berk. & Br.) Y. L. Zhang & T. Y. Zhang.There are also 2 undeterminate species: Verticillium sp. and Ulocladium sp..All specimens (dried cultures) ang living cultures studied have been deposited in the Herbarium of Shandong Agricultural University: Plant Pathology (HSAUP).2. The experience and improvement on taxonomic theory and methods Associated with idiographic identification, the researcher paid great attention to ponder deeply over the basal taxonomic theory at generic and speciies ranks of dematiaceous Hyphomycetes related and to improve the fungal isolation and culture methods.(1) About taxonomic criteria:(ⅰ) Taxonomic criteria at genus levelThe conidiogensis patterns of almost all fungal genera isolated from soil in this study are holoblastic or enteroblastic. But the proliferation patterns of conidiophores (conidiogenous cells) are various, for example sympodial, phialidic, annellidic etc.. Thus, the patterns of conidia formation and conidiophores (conidiogenous cells) proliferation are the main criteria used to separat diferent genera in dematiaceous Hyphomycetes. The morphological characters of conidiogenous cells and conidiophores, patterns of conidia germination and the order of septum (distoseptum) ontogeny are very important in differentiate those genera whose patterns of conidia formation and conidiophores proliferation are the same. Characters, color and growth traits of colonies are useful assistant characteristics to differentiate some genera while absence or presence of setae is also helpful to differentiate a few genera.(ⅱ) Taxonomic criteria at species levelAiming to eliminate the influence of environment, it should culture All species in one genus should be cultured at the same or being close to the same conditions. For those fungi in the genera Ulocladium Preuss, Alternaria C. G. Nees, Curvularia Boedijn, Bipolaris Shoemaker and Exserohilum Leonard & Suggs etc., their conidia shape and size are very easily influenced by environment factors, it should be considered that the culture conditions used by the origional author(s) should be followed as closely as possible. The morphological characters of conidia, especially the shape, size, color, septum and ornamentation etc. are very important in differentiating species. The other parameters such as the ratio of length to width are important in separating species which had similar conidia. The characters of conidiophores and conidia which being steadily play important roles in classing genera, at the same time they are also very useful in differentiating species in some genera. Characters of setae may be used to separat species in a few genera, such as Trichurus Clements & Shear and Myrothecium Tode.In the cource of study we were paid great attention to improve the experaiment methods, and we sum up whatever the lean nutrition TWA+W culture for fungal isolation or the abundant nutrition PDA culture for purifying dematiaceous hyphomycetes from soil, joined with the soil steep, water or plant remains from the sample collection spot can make the culture's nutrition be close to their naturally nutrimental state, and it is very usuful to isolate and purify dematiaceous hyphomycetes. We can not only obtain more fungi genera and species but also make them exhibit representative morphological characters.(2) Improvement in fungal isolation and culture methods:In the cource of the study the most frequently used culture media are PDA, PCA, CMA and TWA+W. PDA is suitable for those slowly growing fungi, whileas the others which being poor in nutrition are adapt to facilitate sporulation. Most fungi are suitable for cultured for about 1-2 weeks under 20-25℃with 12h /12h alternate light and dark. Mechanical damnification and the subsequent melioration of aeration, frozen dealing, short time irradiation under near ultraviolet (NUV) and the use of lixivium of original soil sample or natural substratum are very helpful in stimulating fungus sporulation .3. A brief analysis of the relation between the entironment and dematiaceous hyphomycetes from soil.Among the fungal genera and species got in this study some of them are widely distributed, but some species are regional, for example, Gliomastix murorum (Corda.) Hughes var. polychrom (van Beyma) Dickinson, Phialophora geniculata J. H. van Emden, Rhinocladiella fusiformospora T. Y. Zhang & Y. L. Zhang, Beltraniopsis esenbeckiae Batista & Bezerra, Nodulisporium hinnuleum G. Smith, Domingoella asterinarumPetrak & Ciferri and so on. There is a tendency that the number of species of soil dematiaceous Hyphomycetes in the forest (including national sivan park and other wild holts) are much larger than that in the cultivated land (including farmland, vegetable plot, orchard, nursery and lawn etc.), while the situation in the paddy field (including paddy field and swamp beside the pond of lotus) takes the third position.4. A brief review of the taxonomic status of 3 genera selected, Gliomastix Guguen,Taeniolella S. Hughes and Vernonaea Ciferri & Montemartini. To clarify the taxonomic confusion in the genus Gliomastix it is better to divide the species included into two groups:groupⅠ, conidia catenately produced on conidiophores; groupⅡ, conidia gathered into sticky spore balls on the top of the conidiophores. And the integrated measures, the biological, physiological, ecological, biochemical and molecular biological methods should be used to solve the difficult problems of some species. There are no much difficult in distinguishing species based on the existing criteria in the genera Taeniolella S. Hughes and Vernonaea Ciferri & Montemartini.