Colonization In Tomato And Antagonistic Bacterial Wilt Study Of Bacillus Amyloliquefaciens

Tomato bacterial wilt,caused by Ralstonia solanacearum,is a vascular disease,great concern has been attracted for the biological control of the disease.In this study,the screen of biocontrol strain,entophytic colonization of the purpose strain and their biocontrol mechanism were studied.1.The strains X5 and BQA2,which were better resistant to Ralstonia solanacearum,were screened though the plate antagonism experiment and the pot experiment.X5 and BQA2 were identified as Bacillus amyloliquefaciens by the physiological and biochemical experiments,and 16SrDNA gene.2.The GFP-labeled strains X5-GFP and BQA2-GFP were obtained by modified trehalose electroporation method.X5-GFP and BQA2-GFP colonization in the rhizosphere of tomato were observed using microscope.The experimental results indicated that changing tendency of population quantity in marking strains of tomato rhizosphere was consistent after dealing with individual marking strains or adding Ralstonia solanacearum successively.In the soil,the population of X5-GFP on the roots of tomato reached 1.05x106 cfu/g after inoculating X5-GFP alone,and then decreased 30 days later,eventually remained at 1,50×103 cfu/g.The population of BQA2-GFP on the roots of tomato reached 1.68x106 cfu/g after inoculating BQA2-GFP alone,and then decreased 30 days later,eventually remained at 2.50×103cfu/g.In hydroponics,the population of X5-GFP on the roots of tomato reached 2.70x105 cfu/g after inoculating X5-GFP alone,and then decreased 30 days later,eventually remained at 1.00×1O3Gfu/g.The population of BQA2-GFP on the roots of tomato reached 3.60X105 cfu/g after inoculating BQA2-GFP alone,and then decreased 30 days later,eventually remained at 1.50×103 cfu/g.The results showed that B.amyloliquefaciens X5 and B.amyloliquefaciens BQA2 displayed good colonization ability in the rhizosphere of tomato.3.Tomato was handed with nitrogen fertilizer,phosphate fertilizer,potash fertilizer,compound fertilizer and the labeled strain mixed.The effect of them on the colonization ability of the making strains on tomato root was compared.The results showed the nitrogen fertilizer,phosphate fertilizer,potash fertilizer and compound fertilizer promote the colonization ability of X5-GFP and BQA2-GFP on tomato root.And compared with the four treatment groups,the effect of applying compound fertilizer is better than other treatments.4.Tomato was conducted with the labeled strains and Ralstonia solanacearum respectively.The effect of the labeled strains and Ralstonia solanacearum on tomato growth was observation.The results showed that the labeled strains could promote the growth of tomato plants and roots,especially for the growth of fresh roots and fresh weight of tomato seedlings.However,Ralstonia solanacearum can inhibit the growth of tomato plants.Compared with X5-GFP,the promotive effect of BQA2-GFP on tomato growth was better.5.Tomato was conducted with individual marking strains or adding Ralstonia solanacearum.The effect of them on the defense-related enzyme activities of tomato seedlings was investigated.The results showed that the protective enzyme activities of PAL,PPO,POD,SOD and CAT were significantly increased after the inoculation of individual marking strains or adding Ralstonia solanacearum.The enzyme activity of the mixed treatment was higher than that of the indi’vidual marking strains.It indicated that X5-GFP and BQA2-GFP could induce the resistance of tomato seedling,thereby improving tomato resistance to Ralstonia solanacearum.