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Taxonomic Studies on Soil Dematiaceous Hyphomycetes from the Subtropical Region of Hubei, Sichuan and Guizhou Provinces and the Tableland in Western Sichuan of China

Author: JiangYuLan
Tutor: ZhangTianYu
School: Shandong Agricultural University
Course: Plant Pathology
Keywords: middle-western region of China tableland of western Sichuan Province soil fungi dematiaceous Hyphomycetes taxonomy taxonomic criteria at genus and species level new species new record species to China new record genera to China
CLC: Q949.32
Type: PhD thesis
Year: 2007
Downloads: 180
Quote: 6
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Abstract


Soil fungi are those which have some part of or whole life cycle either in or directly associated with the soil environment. It is a group of organisms which have an immensely diversity. The species of Fungi Imperfeci are most abundant in the soil, of which dematiaceous Hyphomycetes account for about or more than 50 percent of the fungal population. Our country spans cold temperate, warm temperate, temperate, subtropical and tropical zones. The soil and vegetation types are very abundant. Soil as a complex ecosystem, may contains plenty of fungi resources.Hubei, Guizhou and Sichuan Provinces are located in the middle-western subtropical region of China. It is humidy, abundant rainfall, and has a varied topography, hills and mountain ranges undulating. The coverage percentage of the forests is much higher than most parts of China. The excellent vegetation makes the soil diversiform and enrichment where many kinds of known and unknown fungi can inhabit. This study is part of the effort aimed to survey the population of dematiaceous Hyphomycetes from soil at genus and species level from the whole China. A total of 263 soil samples from many representative sites selected in three provinces mentioned were collected. From these samples, 450 fungal strains of dematiaceous Hyphomycetes were isolated by using the soil plate and dilution plates methods. 100 species were discovered which belonged to 43 genera. Among them, 16 species in 3 genera are Stilbellales, 7 species in 2 genera belong to Tuberculariales and 77 species in 38 genera are Hyphomycetales. Thereinto 34 are new species, 4 genera and 11 species are new records to China. All genera and species are fully described and illustrated morphologically. Distribution sites and habitat are also cited.The 34 new species are: Bipolaris fuscae Y. L. Jiang & T. Y. Zhang (the author’s names are same below), Cirrenalia pallescens, Cirrenalia rhodospora, Codinaea brachysetula, Codinaea chinensis, Doratomyces castaneae, Doratomyces macrospore, Doratomyces inflatus, Doratomyces interseminata, Doratomyces ovoideae, Doratomyces pallescens, Doratomyces pedunclensis, Doratomyces pseudorobusti, Doratomyces verruculosae, Eladia inflata, Eladia sichuanensis, Humicola chinensis, Humicola fuscobrunnea, Humicola interseminata, Humicola macrospora, Humicola pallescens, Humicola senseletii, Humicola subminima, Leptographium globosum, Myrothecium bacilliforme, Myrothecium disporum, Pleurophragmium guizhouensis, Scolecobasidium laevis, Scopulariopsis globosae, Scopulariopsis interseminata, Stachybotrys pallescens, Stachybotrys sichuanensis, Torula brunnea and Wardomyces microsporae, respectively.The 4 genera newly recorded to China are Chloridium Link ex Fries, Codinaea Maire, Virgaria Nees & Gray and Wardomyces Brooks & Hansford.The 11 new records at species and variety level to China are: Chloridium virescens (Pers. ex Pers.) W. Gams & Hol-Jech. var. chlamydosporis (van Beyma) W. Gams & Hol-Jech., Chloridium virescens (Pers. ex Pers.) W. Gams & Hol-Jech. var. virescens (van Beyma) W. Gams & Hol-Jech., Doratomyces columnaris Swart, Graphium indicum Chouhan & Panwar, Leptographium engelmanii Ross W. Davidson, Oidiodendron maius Barron, Pithomyces ellisii Rao & Chary, Stachybotrys dichroa Grove, Stachybotrys zeae Morgan-Jones & Karr, Virgaria nigra (Link) Nees ex Gray, Wardomyces inflatus (Marchal) Hennebert. There are also 4 undeterminate species : Chrysosporium sp., Gliocephalotrichum sp., Rhinocladiella sp.and Verticillium sp..The other 51 species have been known to China.All specimens (dried cultures) including the types and living cultures have been deposited in the Herbarium of Shandong Agricultural University: Plant Pathology (HSAUP). Based on literatures related and taxonomic practice, several points of personal experience on taxonomic criteria concerning some genera and species, especially the genera, Doratomyces Corda and Humicola Traaen which more species were isolated.1. The taxonomic criteria at genus levelThe conidiogenous patterns of most fungal genera isolated from soil in this study are holoblastic or enteroblastic except Scytalidium and Oidiodendron which produce their conidia thalicaly. But the proliferation patterns of conidiophores (conidiogenous cells) are various. These two aspects are the main criteria to differentiate most of the dematiaceous Hyphomycete genera. If the above two aspects are the same, the morphological characters of conidiogenous cells and conidia should be used as taxonomic criteria at genus level. The state of conidiophore growth (solitary or somewhat grouped) is useful in differentiating a few Hyphomycete genera. Because the characters, color and growth rate of conlony are easily influenced by environment, they were only been used to ditinguish few genera. The character of the seta and whether it formed or not are useful to differentiate some genera.2. The taxonomic criteria at species level2.1 The commonly used taxonomic criteriaThe conidium shape, size range, color, septum type and number and wall ornamentation etc. are the most important taxonomic criteria in differentiating species. The characters of conidiophores and conidiogenous cells which play important role in classifying genera, at the same time they are very useful to differentiate species in some genera. Characters of colony may be referential to differentiate species in few genera. Characters and situation of the seta and hyphopodium may be used in separating species of some genera.2.2 Some personal opinionsThe size of conidia is very important taxonomic criteria of species so that we usually need measure their size range and average data, but we find out that some species in particular genera don’t need to be measured the average data of conidia but only their size range, for example Stachybotrys chartrum (Ehrenb.) Hughes, Stachybotrys dichroa Grove and Stachybotrys microspora (Mathur & Sankhla) Jong & Davis. Because their conidial size, even their shape change much, their size range can reflect the characters of these species truly, but their average data have little important to taxonomy. But to some species which conidia are tiny and their size doesn’t change much, not only the size range of conidia but also the average datum is important to reflect the character of a species. For example, two species of Eladia G. Smith: Eladia inflata Y. L. Jiang & T. Y. Zhang and Eladia sichuanensis Y. L. Jiang& T. Y. Zhang. Their size ranges of conidia are close which are 3-5.5μm and 2.5-5μm respectively, but their average data are distinctly different which are 4.0μm and 3.4μm respectively. This exmple shows that the average data of conidia is much significant to some species which their conidia are tiny and the size doesn’t change much.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, but also make them exhibit representative morphological characters.There are more new species obtained from less disturbed naturally ecological system. Most of the new species (65.7%) isolated were from soil samples of the forests and hills, and the known species most (69.4%) grow in soils of vegetable field, cropland, orchard, nursery garden, park and greenbelt etc. which were seriously influenced by human activities.

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CLC: > Biological Sciences > Botany > The plant taxonomy (system botany ) > Spore plants (implicit flowering plants) > Fungus > Fungi door
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