Study On The Antibacterial Activity And Mechanism Of Ningnanmycin Against Polychaete Spp

Tea grey blight is a more serious disease in tea areas in Guizhou province,and the tea leaves are the main disease sites.When the tea tree is infected by tea grey blight,the tea tree growth is hindered,and a large number of disease spots are generated on the surface of the leaf,it will cause the shedding of tea leaves,and reduce the yield and quality of tea leaves.so,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.According to the previous work of the research group,it was found that Pseudopestalotiopsis camelliae-sinensis strain GZHS-2017-010 was the pathogen of tea gray blight,so this paper takes this pathogen as the research object to determine the Ningnanmycin agent on tea by the growth rate method.According to the results,Ningnanmycin had a high antifungal activity against Ps.camellia-sinensis,and its EC₅₀ value is 75.92 U.Based on Ningnanmycin has a good high antifungal activity,this paper also studies the mechanism of Ningnanmycin on Ps.camellia-sinensis.In this study,Ps.camellia-sinensis treated at 75.92 U for 14 h,we used electron scanning microscope or electron transmission microscope observed the mycelial morphology of the pathogen after 14 h.Through electron scanning microscope,it was found that the surface of the mycelium treated with Ningnanmycin was not smooth,the branches of the new hypha became thinner,and the new hypha became shorter.Observation of the mycelium treated with Ningnanmycin by electron transmission microscopy revealed that the boundary structure of each organelle inside the mycelium was not clear,each organelle was atrophied,and small cavities appeared.Subsequently,the pathogens treated with 500 U for 1 h and 14 h were transcriptome sequenced.Treat train GZHS-2017-010 by Ningnanmycin for 1 h,929 differential genes were obtained,615 genes up-regulated,314 genes down-regulated;Treat train GZHS-2017-010 by Ningnanmycin for 14h,1692 differential genes were obtained,865 genes up-regulated and 827 genes down-regulated（|log₂ foldchange|≥1,p<0.05）.According to the GO enrichment analysis,it was found that the differential genes were most enriched in the molecular functions of membrane components,transmembrane transport components,and biological processes of the nucleus.Based on the transcriptome data,12 differential genes of the Ningnanmycin 1h treatment group,it was verified by RT-q PCR,the results showed that the expression level of DEGs was consistent with the result transcriptome sequencing.And we analyzed the level of different expression genes in these pathways which involved in Ningnanmycin treatment group.The analysis results showed the gene expression level of DIS3/MCM3/RRP45/LSM3/MNN9/NMT1/RPB7/PIL1/RPN8/CDC3 inPs.camellia-sinensis strain GZHS-2017-010,which all had significantly decreased after Ningnanmycin treatment（1 h/7 h/14 h）on concentration of EC₃₀/EC₅₀/EC₇₀.Based on research results,we preliminarily considered that Ningnanmycin could influence Ps.camellia-sinensis through pathways such as RNA degradation,multiple types of N-glycan biosynthesis,and spliceosome in Ps.camellia-sinensis strain GZHS-2017-010.