Antagonistic Effect Of Bacillus Against Verticillium Wilt Of Cotton In Xinjiang

Verticillium Dahliae is a kind of soil-borne pathogenic fungus with extremely high harmfulness and wide host.As a global cotton disease,Verticillium Dahliae seriously endangers the cotton growing areas in Xinjiang province.At present,there is no effective control measures to control this cotton disease,chemical control caused soil microenvironment pollution;There are many limiting factors in the application of crop rotation,deep tillage and other prevention and control strategies in cotton fields in Xinjiang.The bacterial membrane formed by bacillus can improve plant root colonization and effectively prevent verticillium wilt.In this study,by optimizing the culture conditions of bacillus,the membrane production capacity of bacillus could be improved,and then its inhibitory effect on wilt was improved.Then,the optimized bacillus was applied to the root of two different genotypes of cotton to detect its growth promoting effect on cotton and its ability to prevent and resist verticillium wilt,so as to provide theoretical basis for the prevention and control of verticillium wilt in the future.The main results are as follows:1.Optimize the medium composition by adjusting the PH of the medium,the amount of inoculation,the amount of liquid filling and the temperature of the medium;Through the analysis of the optimization results,it was finally determined that when the culture temperature of Bacillus c-9 was 30?,p H was 5,inoculum was 0.25 ml,and liquid was 20 m L,the density of biocontrol bacteria was the highest and the thickness of bacterial film was larger.2.QPCR technology was used to verify the expression levels of disease-related genes in B.flavescens after the in-dish confrontation between Bacillus and B.flavescens.The gene VMK1 is related to the production of sclerotium.NADPH oxidase gene and GLU reductase gene expression can cause the accumulation of reactive oxygen species.It was found that glycerol-3-phosphate dehydrogenase induced osmotic stress in dendritic cells.The results showed that the expression level of VMK1,GARP and GLU was the highest at 2h,the expression level of G1-3 was the highest at 1h,and the expression level began to decline after 2h.3.The pot experiment was conducted to detect the control effect of Bacillus C-9 on cotton wilt.The results showed that the disease index of infected cotton was decreased and the control effect of verticillium wilt was significantly improved.After treatment with C-9 bacterial solution,the growth promotion efficiency of cotton treated with C-9 bacterial solution was 135.5%,23.7%,27.1% and 12.8%,respectively,compared with that of non-inoculated control(CK).After the biocontrol solution was applied,the activity of relevant defense enzymes,resistance induction,HR reaction and reactive oxygen species of different genotypes of cotton xinluzao 7 and Xinluzao 33 were significantly increased.It showed different signal systems of induced resistance,indicating that C-9 had different mechanisms of induced resistance for different genotypes of cotton.The expression levels of defense-related genes in cotton were detected,and the results showed that c-9 treatment could significantly improve the expression levels of defense-related signal pathways in the two cotton varieties,but there were significant differences in the expression patterns and trends of defense-related genes in the two cotton varieties.