Screening On Antifungal Endo-bacterium And Control Of Sunflower Verticillium Wilt

Verticillium wilt is a serious vascular disease caused by a soil borne pathogen Verticilliu daliae in sunflower. It usually occurs in the main producing areas of sunflower. It is difficult to control because of little research work on occurrence and epidemic regularity. In this study, the biocontrol endophyte were isolated form stems and roots of health sunflower tissue in Hohhot. Bayannur, Chifeng city. Ningxia, Shanxi province and the inhibition effects, colonization level, biological characteristics, synergistic effects with fungicide were studied. The results showed as following.Total of 132 strains were abtained including 124 bacteria.5 fungi and 3 actinomycetes. The strains XT 1-4 and GY3-6 showed the strongest inhibition effects, and the inhibition zone were 12.4 mm and 10.6 mm wide in plates.The strains XT 1-4 and GY3-6 were identified as Bacillus atrophaeus by-morphological. physiological, biochemical characteristics, and 16S rDNA sequence analysis. The strains XT1-4 and GY3-6 could colonize and move in roots, stems and leaves of sunflower by soaking seed and pouring root.The biological characteristics of strains XT 1-4 and GY3-6 were determined. In results, the most optimum incubation conditions were 8 of pH value,32℃ of tempreture,24 h incubating time, and used sucrose and peptone as carbon and nitrogen resourse. put 50 ml laquid medium per 250 ml flask.By testing the synergy of biocontrol bacteria isolated with fungicide, the strains XT 1-4 and GY3-6 could be used for mixing with fungicide, and enhanced the capacity of prevention and control to this diseases.By comparing methods of inoculation, both the leaf-paint assay and root-dipping method could accurately and rapidly evaluate pathogenicity of Verticillium dahliae to sunflower in laborotary.