Isolation And Identification Of Micro-Fungi From Crataegus Pinnatifida With Preliminary Pathogenicity

Hawthorn(Crataegus pinnatifida Bge.,Rosaceae)is a common medicinal and edible plant,which distributes in both temperate and subtropical regions of China.The fruit has a thin skin,a sour and astringent taste,and hard seeds.It can be eaten raw or used to make preserved fruit cakes and also can be used as medicine,thus has important significance in ecology and agriculture.Hawthorn trees are vulnerable to disease,resulting in yield and commercial losses,and if not controlled in time,they will spread in large areas,so disease control is the key to improving hawthorn production and quality.Studies have found that endophytes with potential pathogenic ability can cause plant diseases when subjected to certain conditions,and endophytic fungi have also been found to be involved in the decomposition process of litter.Here,microfungi from leaves of hawthorn in Changchun were studied.Firstly,the microfungi on hawthorn leaves were collected,isolated and identified;secondly,because the morphological and physiological structure of endophytic fungi will be affected by the culture environment,eight media were selected to culture the isolated endophytes,and their biological characteristics were identified,and the most suitable medium for the endophytes of hawthorn leaves was screened;finally,key groups were selected from endophytes and inoculated on fresh healthy leaves,and the virulence test was carried out and evaluated to determine whether endophytic fungi had pathogenic ability and whether there was a difference in the pathogenicity of different forms of the same strain.Analyzes whether endophytes have the possibility of transformation into pathogenic fungi,explores the relationship and interaction between pathogenic fungi,endophytic fungi,saprophytic fungi and leaves,and provides a basis for the biological control of pathogenic fungi.The main results are as follows:1.Using single spore isolation and tissue isolation,and through morphological identification and molecular identification,a total of 35 species of microfungi belonging to 3phyla,7 orders,17 orders,20 families,26 genera were obtained,1 new species of saprophytic fungi,Seimatosporium changchunensis,was discovered,and Coprinellus radians,Psathyrella sp.,Schizophyllum sp.,and Tricharina sp.were obtained through the first isolation of endophytic fungi.Also,Phoma sp.ZMrs01 can exist in three forms: endophytes,saprophytes,and pathogen,and Xylaria oxyacanthae and Microcyclosporella mali show endophytic and saprophytic forms.2.The colony morphology of 30 endophytic fungus on 8 media was described,and the following conclusions were drawn according to the hyphae germination time,mycelial growth rate,and spore production: the most suitable media for the isolation of endophytic fungal hyphae3.germination from hawthorn leaves were MEA and OA mediums;the most suitable media for the growth of endophytic fungal hyphae in hawthorn leaf isolation were OA medium and PDA medium;the most suitable screening medium for endophytic fungi spore production in hawthorn leaf isolation were OA medium and PDA medium.In summary,if hawthorn leaf endophytes isolation was needed in the follow-up experiments,OA medium can be used.4.Phoma,Nigrospora and Cytospora were selected for pathogenicity determination,and it was found that all of them had the ability to make healthy leaves sick.According to Koch postulates,the hyphae or conidia on the inoculated leaves were microscopically observed,then isolated and cultured and sequenced,which was consistent with the inoculated strain.This demonstrates the potential for endophytes to transform into pathogen and/or saprophyte,and that strains with documented pathogenicity,even in endophytic form,remain pathogenic.