The Research On Biochemistry Mechanism Of Biological Control Diseases And Promotion Growth Of Plants By Endophytic Bacteria(Bacillus Subtilis) 29-12 From Eggplant (Solanum Melongena)

The Verticillium wilt is one of the most important diseases of eggplant; it is harmful to their host plants in the north and south of China seriously. At present, chemistry way is often used to control the Verticillium wilt, and it does not have other effective solution. Endophyte is a kind of important microorganism resource which receives widely attention more than ten years ago, and endophyte may have potential application value in biocontrol. In order to gain some endophytic bacteria which having remarkable control effect against the Verticillium wilt, many kinds of endophytic bacteria have been isolated from eggplant, and one of them 29-12 have strong antagonism to Verticillium dahliae, and have some biocontrol effect on Verticillium wilt. In order to explore its antimicrobial mechanism, we carry out this research on colonization promoting plant growth.The mutanted by antagonism against the pathogen and the rifampicin, and inoculated by acupunctureing stems, daubing leaves, and watering roots, 29-12 was proved to be able to colonize in the eggplant.The results also showed that the 29-12 strain by different inoculation methods was able to live and move in the plants of eggplant and the 29-12 could live in the eggplant plant for longer time by watering roots .The growth of eggplant were not significantly promoted by watering root with fermentation precipitum supernatant of 29-12 strain. Compared with the control, supernatant of 29-12 strain have conspicuous promoting effect on the growth of eggplant about plant height root length dry weight net weight. Fermentation precipitum of 29-12 strain have no evident promoting effect on eggplant.The different treatments of 29-12 strains were used to control the Verticillium wilt of eggplant. The result showed that the Verticillium wilt of eggplant was controlled effectively by endophytic antifungal bacterial strains. Tests showed that the disease occurrence was delayed and the disease rate was decreased by endophytic bacteria. These different treatments (fermentation precipitum supernatant ) of 29-12 also gave 100% 60.0% 87.5% control efficacies to the Verticillium wilt of eggplant 15 d after inoculating the pathogen by pouring root. Even at the 24th day, their control efficacies can reach to 82.5% 79.07% 22.50% respectively.The research on biological control mechanisms showed that the 29-12 strain could inhibit the mycelial growth and the germination of conidiospore of Verticillium dahliae by secreting the antifungal substance, regulating the activities of SOD, POD, CAT, PAL in eggplant when Verticillium dahliae was inoculated, were proposed to be the key mechanisms of strain 29-12 on controlling the Verticillium wilt of eggplant.