Isolation,Identification,Infection Mechanism And Biological Control Of The Pathogen Causing Yellow Blotch Disease In Pleurotus Ostreatus

Pleurotus ostreatus is one of the largest edible fungi in China.In recent years,yellow blotch disease has experienced different degrees of outbreak in the main producing areas of P.ostreatus in China,and the quality and yield of P.ostreatus in the outbreak area seriously affected.In this study,P.ostreatus fruit-body with yellow blotch disease was used as the research object.The pathogens were isolated by dilution coating method and Koch's rule,16 S r DNA,gyr B and rec A were used to identify the pathogens,and pathogenic bacteria were identified by combining physiological and biochemical indicators.The infection mechanism of P.ostreatus yellow blotch disease was studied by transcriptomics,and some differentially expressed genes were verified by q RT-PCR.On this basis,the biological control of P.ostreatus was studied.It provides valuable information for further research on the pathogenesis of pathogenic bacteria infection and the prevention and treatment of yellow blotch disease and other edible fungi diseases.The main findings are as follows:1.Gram staining and scanning electron microscopy showed that the pathogen was gram-positive and rod-shaped.The phylogenetic tree was constructed by sequencing with 16 S r DNA,gyr B and rec A.The pathogen strain HB-1 of P.ostreatus was on the same branch as Bacillus velezensis and B.amyloliquefaciens.The pathogen of Pleurotus ostreatus was determined to be B.amyloliquefaciens by physiological and biochemical indicators.2.High-throughput RNA sequencing(RNA-seq)technology was used to study the transcriptional expression level of pathogen-infected P.ostreatus-related genes.Compared with the healthy oyster mushroom fruit body tissue,a total of 486(295 up-regulated,186 down-regulated)genes were identified as differentially expressed genes in infection P.ostreatus.20 genes(10 up-regulated,10 down-regulated)were selected for q RT-PCR validation.Among them,14 differentially expressed genes were consistent with transcriptome sequencing results,5 differentially expressed genes were inconsistent with transcriptome sequencing results and 1 differentially expressed gene is reversed from the transcriptome sequencing results.The results of the differential analysis showed that 66 up-regulated differentially expressed genes and 42 down-regulated differentially expressed genes were associated with 63 and 39 specific KEGG pathways,respectively.The differentially expressed genes involved in amino acid metabolism,carbohydrate metabolism and energy metabolism and signal transduction pathway respond to the mechanism of pathogenic bacteria infecting P.ostreatus fruit-bodies,which is related to the mechanism of pathogenic bacteria infecting P.ostreatus.3.Measured and analyzed the ethanol extracts of different substances to observe the bacteriostasis test of the isolated pathogens and diseased fruit-bodies of P.ostreatus.In the bacteriostatic test,the ethanol extract of vinegar and the ethanol extract of wine residue had better inhibition effect on the pathogen of P.ostreatus yellow blotch disease,and the ethanol extract of vinegar with 0.06 g/m L was the best.After that,Acetobacter BA15 was fermented.The results showed that: Acetobacter BA15 fermentation broth cultured at 160 r/min for 7 days at 30 °C had significant inhibitory effect on the pathogen strain HB-1 of P.ostreatus yellow blotch disease and diseased fruit-bodies.