The Study Of The Species Diversity Of Didymellaceae And Plectosphaerella In Endophytic Fungi Of Aquatic Plants

As one of the most species-rich families in the fungal community,the Didymellaceae have a wide range of habitats.From plants to animals,soil to air,the membres of Didymellaceae can be found everywhere.The genus Plectosphaerella is a typical plant pathogenic fungi,often cause flowers and crops wilting corruption.Both fungi have been reported in terrestrial plants,but they have not been mentioned in aquatic plants.This study mainly focused on the species diversity of the Didymellaceae and Plectosphaerella in endophytic fungi of aquatic plants in southwestern China.Endophytic fungi were isolated from aquatic plants collected from several freshwater lakes,rivers and wetlands in Yunnan,Guizhou and Sichuan Provinces.The isolates of these two taxa were identified by molecular systematics and morphology.The new species and new genus are described and illustrated in detail.At the same time,the pathogenicity test was carried out on the suspected new species of the genus Plectosphaerella.Below are key research findings:1.About 1600 endophytic fungi were isolated from nearly 20 kinds of aquatic plants collected,including 88 strains of Didymellaceae and 29 strains of Plectosphaerella.2.The combination of four loci,LSU,ITS,rpb2 and tub2,were analyzed by Bayesian and Maximum Likelihood Method to identify the strains of Didymellaceae.Their morphological characteristics were also evaluated.In this study,we identified nine known species: Allophoma labilis,Boeremia exigua var.linicola,Boeremia exigua var.pseudolilacis,Didymella aurea,Didymella glomerata,Didymella sinensis,Epicoccum huancayense,Epicoccum latusicollum,Epicoccum plurivorum,two new genera: Qionghaimyces,Erhaimyces,eighteen asexual new species: Stagonosporopsis malaiana,Boeremia exigua var.vulgaris,Boeremia exigua var.yilensis,Boeremia exigua var.litangensis,Boeremia exigua var.kasensis,Boeremia exigua var.ruoergaiensis,Boeremia exigua var.baiyusis,Qionghaimyces spicatum,Qionghaimyces nuttallii,Erhaimyces hydrillanus,Didymella hippuris,Didymella yilensis,Didymella erhaiensis,Didymella gongkaensis,Didymella myriophyllana,Didymella kasensis,Didymella lijiangensis,and Six sexual new species: Stagonosporopsis caohaiensis,Stagonosporopsis bungeiana,Didymella qisehaiensis,Leptosphaerulina hippuris,Leptosphaerulina kaisasis,Leptosphaerulina shangrilensis.3.The combination of two loci,LSU and ITS,were analyzed by Bayesian and Maximum Likelihood Method to identify the strains of the genus Plectosphaerella.Their morphological characteristics were also evaluated.Three new species: were identified: Plectosphaerella erhaisis,Plectosphaerella potamogeton,Plectosphaerella yunnansis.4.The pathogenicity tests on nine strains of three new species of Plectosphaerella showed that all nine strains caused wilting corruption in flower and leaf of Lilium brownie.It is indicated that the parasitic strategy of some fungi in aquatic plants and the obvious difference in terrestrial plants.