Isolation Of Endophytic Fungi From Three Pistils Mutation In Wheat And Screening Activity Strains Against Pathogenic Fungi

In the process of symbiosis between plant endophytic fungi and host,the secondary metabolites with the same or similar functions as the host can be produced.The host provides a nutrient source for endophytic fungi,and the secondary metabolites secreted by endophytic fungi enhance the host's disease resistance,stress resistance,insect resistance and so on.Wheat is one of the most important food crops in the world.However,affected by pests and diseases,wheat grain production has been limited.Increasing wheat yield and quality is one of the main means to solve food problems.Tripistil mutant(TP)of wheat is a mutant wheat with three pistils in a spikelet which can be inherited stably and was cultivated by Professor Peng Zhengsong for many years.The shape of three pistils is controlled by Pis1 gene on the long arm of the 2D chromosome,which has nothing to do with cell heredity.The number of wheat grains was increased and the yield was increased.In this study,TP was used as material to isolate endophytic fungi from healthy wheat plants,identify their species,and screen endophytic fungi that have antagonistic effects on plant pathogenic fungi,so as to provide material and theoretical basis for biocontrol research.The results are as follows:1: Tissue isolation was used to isolate 58 endophytic fungi from roots,stems and leaves of healthy TP plants.Among them 34 strains were isolated from roots,14 strains were isolated from stems,and 10 strains were isolated from leaves.According to morphological and molecular identification,58 strains of endophytic fungi belong to 12 genera,namely,Fusarium sp.?Arthrinium sp.?Mortierella sp.?Cylindrocarpon sp.?Chaetomium sp.?Talaromyces sp.?Cladosporium sp.?Pleosporales sp.?Microdochium sp.?Xylaria sp.?Plectosphaerella sp.?Emericellopsis sp.etc.Among them,Fusarium is the dominant strain.2: 58 strains of endophytic fungi were studied.Five plant pathogens,including Fusarium graminearum,Pythium,Dry rot of potato,Rhizoctonia solani and Alternaria solani,were tested.TP endophytic fungi with inhibitory effects on plant pathogenic fungi were screened by plate confrontation method and mycelial growth method.It is shown that 44 endophytic fungi had antagonistic activity against at least one pathogen tested.3: With strain Talaromyces flavus G12 as the research object,mycelial growth method was used to detect the inhibitory effect of different organic phase extracts on Fusarium graminearum in order to determine the optimum extraction site.Agar culture and droplet method were used to detect the effect of the best extracting site on spore morphology and germination rate of Fusarium graminearum.It is shown that ethyl acetate extract of strain G12 had the best inhibiting effect on mycelium of Fusarium graminearum,and the inhibiting rate was 85%.The extracts from this part can cause mycelial growth of Fusarium graminearum to be deformed and nodular,and inhibit its spore germination.Further studies on the mechanism of the fungus inhibiting Fusarium graminearum still need to be carried out.