The Research Of Taxonomy With Molecular Systematic On Myrothecium And Stachybotrys

Myrothecium and Stachybotrys classified into Ascomycota,Pezeizomycotina,Sordariomycetes,Hypocreomycetidae,Hypocreales,Stachybotryaceae.Species of Myrothecium and Stachybotrys are saprophytic and weakly parasitic fungi with widespread in soil,growing plants or its residual and indoor environment.Some species are able to pollute air to endangering people health and work as pathogens to infect many plants.However,a variety of secondary metabolites from parts of species could be utilized in fields of medical,agriculture,etc,which are beneficial to people health with development value.The genus Myrothecium has distinctive characteristics in massive half-liquid or sticky conidia covering on sporodochial.The special characters of Stachybotrys are hyphae,phialidic,transparent,light to dark;conidiaphore erect stems growing from hyphae;conidia viscous bud spore,single-celled,color dark,often adhesion clusters.Although the definition of genera Myrotheium and Stachybotrys were accepted by researchers in a long term,as a big controversy,placement of many species is chaotic because of 1)morphological characters shortage and unstable;2)the limits of classification is unclear.Meanwhile,morphologies explain phylogenetic relationship among species insufficiently.In recent,parts of molecular systematic researches also illustrated many taxonomical problems in two genera which need to be solved in further work.Through collection and isolation strains,the research was to discuss classification problems by combining morphology and phylogeny.The research collected 44 Myrothecium strains in total from 2014 to 2017,including that 35 strains isolated from 40 soil specimens in province of Guanxi,Guizhou and Chongqing,9 strains collecting from Shandong Agriculture University.Stachybotrys have 77 strains from the laboratory of plant pathology,Guizhou University.The main morphological characteristics in species level conclude conidia shape,size,color,septate or aseptate,quantity,surficial grain and parts of conidiaphore and conidiagenous charactes.On the basis of morphology,8 genes(cmdA?ITS?LSU?rpb1?rpb2?SSU?tef1 & tub2)were utilized to analysis differentiation and credibility by building single and multigene tree,using three analyses methods of Maximum likelihood,Maximum parsimony and Bayesian inference.The study demonstrated the placement of 30 Myrothecium and 41 Stachybotrys,besides four Myrothecium-like novelties: Paramyrothecium guiyangense sp.nov.,Par.huasicola sp.nov.,Par.lenriicola sp.nov.,Par.verruridum sp.nov.,two Stachybotrys-like news: Stachybotrys sp.nov.,Striatibotrys verrucaspora sp.nov..Additionally,two new Myrothecium-like genera: Conimyrothecium gen.nov.,Lengimyrothecium gen.nov..The single gene trees show the degree of differentiation discrepantly,cmdA?rpb2 best-fit for Myrothecium-like,following genes tef1,tub2,ITS,LSU lastly;and cmdA rpb2 being good-suited for Stachybotrys-like,following ITS and tub2,LSU and tef1 gene lastly.Furthermore,the analysis of multigene is better than each single gene to solve confused species in two genera.Specimens and strains were stored in the laboratory of plant pathology,Guizhou University.