Isolation And Identification Of A Strain Of Tomato Endophytic Actinomycetes Against Verticillium Dahliae

As the tomato cultivation area expanding, more and more unreasonable cultivation way appears in production practice. Adding the difficulty of crop rotation, and years of planting, greenhouse vegetables often performance the phenomenon of plants reproductive slowly, growth potential dropped, quality becoming worse, soilborne pathogens accumulating a lot, and fungal diseases happen a lot. Verticillium dahliae is one of the main symptoms in the greenhouse tomatoes, that has become the bottleneck problems of restricting tomato productio n and commercialization. Actinomycetes is a kind of main assumes the hypha growth and to spore reproductive land naturally strong prokaryotes, widely existing in different natural ecological environment. There are in a wide variety, and different metabolic function. Many of them have good control effect against the fungal disease. Actinomycetes are also many antibiotics and growth hormones production. So far, we have found more than 20000 kinds of bioactive substances, and about 45% is produced by Actinomycetes. And as source of advantage bacterium process commercially being biocontrol agents, biological organic fertilizers and so on.In order to explore an effective biocontrol role of endophytic actinomycetes resources, this present study choosing five separation medium respectively cultivation within the health and disease of tomato roots and rhizosphere soil. The strains obtained through preliminary duplication culture characteristic and the colonial morphology characteristic. Then tablets in vitro inhibit ory experiment was carried out, respectively for the spore suspension and fermented liquid of actinomycetes screening of antifungal activity. Matching the field seedling test, further validation of actinomycetes and role in the growth of resistance, and th e colonization ability. We get after screening effective strain, the inhibitory action of 16 S r RNA gene sequence amplification and sequencing, and The combination of morphological characteristics and physiological and biochemical characteristics to multiphase classification identification of the bioactive strain. Ultimately, for purpose of Actinomycetes strains will be get and identified. For the future development and utilization of endophytic actinomycetes resources screening to provide data support and practical basis of disease resistance. And the source of endogenous actinomyces separation targeted choose to provide a reference basis. At the same time in the future production practice of biocontrol agent preparation and use of bio-control bacteria resources accumulation.The research main conclusion as follows:(1)With the root of diseased tomato plants and the closed the healthy ones as separate source, a total of 86 different strains of actinomycetes were isolated. Among them, 50 strains from healthy plants, 36 strains from disease plants. 32 actinomycetes strains were isolated in the root and 54 actinomycetes strains isolated from rhizosphere soil.(2)For 86 actinomycetes strains were isolated in vitro antagonism activity assay, 8 strains have inhibitory effect on pathogenic fungi. The inhibitory action in the 8 strains, 3 strains(HHV1-5, HGS2-9, HAAG3-8) from the healthy plants, 5 strains(DDPA1-2, DHV3-2, DAAG1-10, DGS3-6, DGS2-8) from the diseased plant. The DHV3-2 has a maximum inhibition effect on tomato verticillium wilt fungus, the inhibition zone is 18.2 mm, inhibit activity is significantly higher than other actinomycetes. In addition, DHV3-2 also showed bioactivity to many pathogenic fungi.(3)The polyphasic taxonomy identification of the strains DHV3-2, develop characteristic identification by molecular biology identification, morphological and physiological and biochemical characteristics of identification, and finally confirm the strains belong to Streptomyces.This study first reported on the strain isolated from plants and have prevention and cure function to fungal diseases.(4)According the tomato seedling assay, inoculating high concentrations of actinomyces DHV3-2 has obvious inhibitory effect on tomato verticillium wilt disease incidence and disease index were both significantly reduced. And there is a certain role in the growth, significantly increased the plant height, the ground of tomato seedling fresh weight and whole plant fresh weight. And it has certain colonization ability in the roots and the rhizosphere soil by tomato seedlings.