Identification Of Strain G-1 And Its Antagonistic Mechanism Against Botrytis Cinerea Preliminary Study

In order to obtain an advantageous biocontrol strain capable of effectively controlling Botrytis cinerea,this study used plant endophytic G-1 as the research object,its antibacterial spectrum,taxonomic status,type of antibacterial substance and its antibacterial substance against Botrytis cinerea The bacteriostatic mechanism of the disease was studied initially.The main research results are as follows:1.Using the plate-to-spot method,9 species of pathogens such as Botrytis cirerea,Sclerotinia sclerotiorum,Fusarium oxysporum f.sp.lycopersic,Monilinia fructicola,and Alternaria solani were used as indicator bacteria to carry out antifungal against endophytic G-1.The activity of the spectrum was determined.The results showed that G-1 had the best antibacterial activity against Botrytis cinerea and Monilinia fructicola,and the inhibition rates were 83.14% and 81.65%,respectively,and the strain was against Alternaria,Fusarium and so on.Has a good antibacterial activity.2.Identification of endophytic G-1 as Bacillus methylotrophicus by morphological observation,physiological and biochemical characteristics detection and 16 S r DNA combined with gyr A,gyr B and other polygenes.3.Studies on the antibacterial activity and antibacterial substance types of endophytic G-1 metabolites showed that the metabolites of G-1 strain had higher antibacterial activity against Botrytis cinerea,and the inhibition rate was 85.87%.Its metabolites have strong thermal stability,the inhibition rate at 121 °C is 81.76%,the acid-base stability is good,and it has strong anti-ultraviolet radiation ability.The inhibition rate after UV irradiation for 24 h is 85.68%.4.Using Botrytis cinerea as indicator bacteria,the antibiotics of endophytic G-1 were crudely extracted by acid precipitation,and the antibacterial substances were separated and purified by medium pressure chromatography and high performance liquid chromatography.After HPLC purification,it was found by LC-MS that strong absorption peaks appeared at 29.08 min,30.07 min,31.73 min,and 40.05 min,and the main antibacterial substances of endophytic G-1 were mainly determined to be Isophyrin A and Antibacterial lipopeptides such as abundance B 1465 D.5.The bacteriostasis mechanism of G-1 strain inhibiting Botrytis cinerea was studied by scanning electron microscopy.The results showed that after the antibacterial peptide treatment of G-1 strain,the hyphae of Botrytis cinerea showed abnormal growth and bacterial malformation.,a large amount of internal dissolved matter caused by the phenomenon of bacterial digestion.6.In order to explore the mechanism of antibacterial peptide inhibition of Botrytis cinerea,the Botrytis cinerea was treated with antibacterial peptide for 3d and 5d respectively,and RNA was extracted and sequenced and analyzed by transcriptome.A total of 22.33 Gb Clean Data was obtained from transcriptome sequencing,and 12084 of the total annotated genes were matched to homologous genes in the NR database,accounting for 98.99% of the total annotated genes.The GO and KEGG enrichment analysis indicated that the endophytic G-1 antimicrobial peptide could inhibit the growth of mycelium and spore by inhibiting SDH and HMGR in the cell membrane fraction of Botrytis cinerea.RT-PCR confirmed that Bcin01g00020,Bcin01g00030,Bcin04g04450,Bcin03g05820,Bcin04g03050 and Bcin04g05700 were lowly expressed by antibacterial peptides,and Bcin01g03520 and Bcin08g04970 were highly expressed by antibacterial peptides,and the results of transcriptome analysis were analyzed.Consistent.