The Screening Of The Pharmacological Activity Of Pseudochaetium Tea And The Study Of Its Antibacterial Mechanism

Tea gray blight is a common tea leaf disease that mainly damage tea leaves.When the disease occurs seriously,it will cause the shedding of tea leaves,weakening the tea trees,that reduce the yield and quality of tea leaves.Therefore,it is of great significance to isolate and identify the pathogen of tea gray blight,screen the effective biogenic pesticides and further study the mechanism of antifungal activity.In this paper,the antifungal activity of Shenqinmycin against the pathogen of tea gray blight disease which isolated from Huishui county,Guizhou province was determined.The results showed that Shenqinmycin had a high antifungal activity against the pathogen,with EC₅₀ of 11.23μg/mL.In order to further study the mechanism of Shenqinmycin action on Pseudopestalotiopsis camellia-sinensis,the morphological changes were observed by optical microscope,electron scanning microscope and transmission electron microscope,and it was found that the hyphae represented shorter,deformed,and extracellular exopolysaccharides changed lesser,as well as organelle structures being destroyed.Subsequently,transcriptome sequencing was performed on the pathogens treated at 11.23μg/mL for 12 h,and 3388 differentially expressed genes were obtained,including 1705 up-regulated genes and 1683 down-regulated genes.Based on the GO and KEGG enrichment analysis of the differentially expressed genes,it was found that the differentially expressed genes were mainly involved in the synthesis of mannose and the activity of transferase and oxidative phosphorylation,ribosome synthesis and various types of N-glycan biosynthesis pathways.The enzyme activity of catalase was increased and the reactive oxygen species（ROS）accumulated in the pathogen after treatment.Finally,RT-qPCR was used to verify the differentially expressed genes of the group treated with 11.23μg/mL for 12 h,and the related genes of mannose synthesis and other pathways of the P.camellia-sinensis treated with different concentrations of Shenqinmycin at different times were studied.The preliminary results show that Shenqinmycin can affect the electron transfer in the cell of pathogen,and cause damage to the cell with the increase of ROS.At the same time,it can also affect the synthesis and transfer of intracellular mannose,which is manifested as the reduction of extracellular polysaccharides.