A Study On Pathogenic Fungus Diversity Of Natural Microstegium Vimineum Populations

Microstegium vimineum is an annual herbaceous grasses origin from East and Southeast Asia.Due to human activities,it was brought to the United States in the 20th century.Because of its high-efficiency photosynthetic efficiency and the seed with strong vital force,it rapidly invaded the eastern United States,now it has become a vicious invasive weeds.Its invasion has a huge impact on the local ecology including reducing the living space of local parts of the plants,changing the soil biological composition and local soil physical and chemical properties which makes it difficult to recover ecological environment of local place where M.vimineum was controlled successfully.Current,the way to control it is physical and chemical methods,but effect is very limited.Bio-herbicide has been reported to be used other weeds successfully,but it is rarely to use biotechnology to control M.vimineum.There is no systematic study of Natural enemies of M.vimineum.So applicable candidate biocontrol creatures were not found.Thus it is necessary to investigate natural disease of M.vimineum and solate and identify pathogenic fungi for providing potential creature to control M.vimineum.During 2014 and 2015,we travelled Jangsu Province,Hebei Province,Anhui Province,Zhejiang Province,Hunan Provinceand Jiangxi Province in China totally 39 sample spots to investigate natural disease and collect disease samples.Except Huaibei in Anhui and Xuzhou in Jiangsu,Microstegium vimineum was found.We have collected 434 samples.We got 381 fungi totally.We describe symptom of plant disease.Inoculating stipe on fresh and non-lesion leaves,observing the incidence,If it shows disease symptom,that string has virulence on Microstegium vimineum.Finally,we confirmed 82 pathogenic fungi.To identify these 82 strains pathogenic fungi,we culture pathogenic fungi and induce spore production.According to morphology of conidium and conidiophore to identify pathogenic fungi.And we use ITS sequence to identify pathogenic fungi.Amplifying DNA of pathogenic fungi to get information of ITS sequence and aligning sequence.We draw a phylogenetic tree pathogenic fungi to confirm the evolutionary relationships with other strains.Finally 10 genuses and 19 specieses was confiemed.19 speciese are Bipolaris oryzae,Bipolaris setariae,Bipolaris sacchari,Bipolaris sorokiniana,Bipolaris panicimiliacei,Bipolar is maydis,Bipolaris zeae,Curvularia lunata,Curvularia geniculata,Curvularia intermedia,Nigrospora oryzae,Nigrospora sphaerica,Phoma herbarum,Alternaria tenuissima,Corynespora cassiicola,Gloeocercospora sorghi,Pestalotiopsis theae,Drechslera erythrospila,Exserohilum rostratum.Microstegium vimineum has diversiform types of pathogens,Bipolaris setariae,Bipolaris sacchari,Bipolaris panicimiliacei,Nigrospora oryzae,Nigrospora sphaerica and Phoma herbarum are dominant species.ITS sequence of the same species but different strains exists base substitution and base add and missing.And the morphology of strains shows differerce.It shows genetic diversity of pathogenic fungi.Pathogenic fungi show diversity in the geographical distribution,the same species distributes difference provinces,a province has multiple species.Pathogenic fungi have widespread host range including common Poaceae crops and weeds.With the situation of agricultural production in The USA and the distribution of M.vimineum in The USA,Bipolaris could be regarded as biocontrol bacterium in some areas where grows non-Poaceae crops.Phoma herbarum could be regarded as biocontrol bacterium in some areas where grows Poaceae crops.