Response Of Endophytic Bacteria In Potato Leaves And Rhizosphere Bacteria To Feeding Stress Of Phthorimaea Operculella

Potato is a major food crop in China and faces the impact of Phthorimaea operculella feeding damage both in the field and during storage.It is important to investigate the response of potato leaf endophytic and inter-root bacterial communities to P.operculella feeding stress and to further screen for beneficial leaf endophytic and inter-root bacteria for green ecological cultivation of potato.In this study,the main potato"He-zuo 88"in Yunnan Province was used as material.Isolation culture method and high-throughput sequencing technology were used to determine the composition and diversity of endophytic bacteria and rhizosphere bacteria in potato leaves under the feeding stress of tuber moth.A total of 30endophytic and inter-rhizosphere bacteria were screened by CAS,PKO medium and Salkowski’s colourimetric method for their growth-promoting effect on potato and their potential to prevent potato tuber moth.The main findings are as follows:Structure and diversity of endophytic bacterial composition of potato leaves in response to P.operculella feeding stress.After feeding stress of tuber moth for 12,24,36and 48 h,7,16,7 and 11 bacterial strains were isolated from potato leaves,respectively.The dominant bacteria were Firmicutes,Proteobacteria and Actinobacteria,After feeding stress,the dominant bacteria and relative abundance of isolated endophytic bacteria in potato leaves changed significantly at phylum and genus levels,and Staphylococcus strains increased significantly.High-throughput sequencing results showed that the ACE index and Chao1index of endophytic bacteria in potato leaves increased significantly under feeding stress,indicating that the species richness of endophytic bacteria in potato leaves increased significantly after feeding stress.The dominant bacterial groups of endophytic bacteria in potato leaves before and after stress were Proteobacteria,Actinobacteria and Firmicutes.The relative abundance of Actinobacteria increased by 343.47%,367.74%,341.10%and 504.91%at 12,24,36 and 48 h after stress,respectively,while the relative abundance of Proteobacteria and Firmicutes decreased.At the Genus level,the relative abundance of Enterobacter was significantly increased after feeding stress,while the relative abundance of unclass＿f＿Alcaligenaceae and unclass＿p＿Proteobacteria decreased.Response of bacterial composition and diversity in potato rhizosphere to feeding stress of tuber moth in potato.The feeding stress of P.operculella caused changes in the composition and structure of rhizosphere bacterial community.There were significant differences in the rhizosphere bacterial community structure at seedling stage,tuber formation stage,starch accumulation stage and maturity stage,among which the rhizosphere bacterial species richness was the highest at maturity stage.At potato seedling stage,after12,24,36 and 48h feeding stress,9,9,13 and 12 species of culturable bacteria were isolated from the rhizosphere in the treatment group and 15,9,13 and 9 species were isolated from the control group,respectively.Bacteroidetes of Actinobacteria,Proteobacteria,Firmicutes and Bacteroidetes in the treatment group and control group were the main bacteroidetes of16S r RNA sequencing,while the main bacteroidetes of 16s r RNA sequencing were Actinobacteria,Proteobacteria,green bent Bacillus,Acidobacteria and Firmicutes.After feeding stress,the relative abundance of bacteria in potato rhizosphere changed significantly,the relative abundance of Actinomycetes and Proteobacteria increased,while the relative abundance of Acidobacteria decreased.At the Genus level,the relative abundance of Arthrobacter significantly increased after feeding stress,increased by 137.39%,113.58%,93.12%and 61.87%at 12,24,36 and 48 h,respectively,after feeding stress,the relative abundance of norank＿f＿norank＿0＿Vicinamibacterales and norank＿f＿Vicinamibacteraceae decreased.Identification of endophytic bacteria with insecticidal activity in potato leaves under stress.Two strains of insecticidal active bacteria were isolated and identified from potato leaves stressed by tuber moth feeding,they were salt-tolerant Bacillus halotolerans HZ 36-13 and Bacillus pacificus HE 36-9.Isolation and identification of growth-promoting bacteria from potato leaves and rhizosphere under stress.Thirty strains of growth-promoting bacteria were isolated from potato leaves and rhizosphere under feeding stress of P.operculella.There were 24 strains of IAA-producing bacteria,The IAA yield of Agrobacterium tumefaciens H36-12,Bacillus Priestia megaterium H 36-8 and Arthrobacter globiformis H 24-5 strains was high,34.03mg.L^-1,25.18 mg.L^-1 and 22.08 mg.L^-1,respectively.Phosphorus solubilizing ability of Bacillus amyloliquefaciens H 48-8 and Bacillus amyloliquefaciens H 36-6 by PKO screening of endophytic bacteria from leaves.Strains H 48-1,H 48-6,H 24-9 and H 24-2 had the ability to produce iron carriers,with iron carrier synthesis rates of 33.87%,16.13%,29.57%and69.57%,respectively.