| Banana Fusarium Wilt is caused by Fusarium oxysporum type specialization Cuba(Fusarium oxysporum f.sp. cubense, FOC), is a worldwide devastating disease on banana. The fungus can be spread in soils and attacks the vascular bundles. In our country, such as Guangdong, Guangxi, Fujian, Hainan provinces are distributed, as well as the rest of the world banana growing areas. With the rapid spread and the difficult controlled of fusarium wilt disease, it has brought huge threat to banana-growing industry. Here, we attempted to take Bacillus amyloliquefaciens as a subject to control banana disease. Using the Fusarium oxysporum f.sp. Cubense race4(FOC4) as a target pathogen, This paper has carried out the separation and screening of antagonistic bio-control bacillus strains, researched on the identification, mark, potential analysis of colonization in soil and control effect of the strains by potted plants in different disposal methods.The Fusarium oxysporum f.sp. cubense race4(FOC4) as target pathogen. Thirty antagonistic strains were isolated from eighty strains by plate-confrontation method, and10strains were further confirmed have a good antagonistic effect on control the target pathogen. Then obtained three strains which have a high level of producing chitosanase through transparent ring method of Chitosan. Integrated the three strains of antagonism and chitosanase producing ability, Selected strain C10-1as bio-control strains, which has a strong antifungal rate (58.7%) and4mm wide of hydrolysis circle cultured in solid medium with chitosan. Spores of Fusarium oxysporum f.sp. cubense race4can be bulking deformation and there is a lot of bubble formation in the middle of pathogenic fungus mycelia by the fermentation broth of C10-1strain. Through the morphological features, physiological and biochemical properties and16SrDNA sequence analysis of the C10-1strain, it can be classified as Bacillus amyloliquefaciens.In order to have a better colonization detection of C10-1in the soil as well as in the banana plant, rC10-1strain which can resist rifamycin(250μg/ml) antibiotic, was selected by spontaneous mutant and marked from wild type strain. It has normal growth on the tablet of rifamycin antibiotic and no obvious change with wild type strain in performance of antagonism. So we got two specific properties of antagonistic bacteria rC10-1strain which can distinguish with other soil microbial.Through Bacillus amyloliquefaciens rC10-1strain, which is antagonistic, marked and producing chitosanase, we studied the effect of different treatment of the strain rC10-1on colonization in the soil. Founding that in the dispose of fermentation solution, as well as bacterium suspension, the colonization falling range in the infested soil of Fusarium oxysporum f.sp. cubense race4(FOC4) all greater than CK, the sick soil dealt with water, so did the treatment of LB culture medium.(The FOC4survival differences were74-fold).Therefore, illustrating that the fermentation solution and bacterium suspension of strain rC10-1all had a good inhibition effect on Fusarium oxysporum f.sp. cubense race4, which is consistent with indoor tablet inhibit experimental results. The colonization dynamics trend of the marked antagonistic bacteria rC10-1strain presented wave downward both in the normal and sick soil. All processing amount of bacteria colonization in the normal and sick soil tended to be a stabilized level after inoculated the Bacillus amyloliquefaciens rC10-1strain35days, the bacterial in the soil were decreased from3.16×107cfu/g to3.0×103cfu/g. The result indicated that the Bacillus amyloliquefaciens rC10-1strain has the colonization ability to exist in the soil. The growth and decline of pathogenic fungus in the sick soil also had a wave mode. During initial period, the number of pathogenic fungus in the soil which disposed by the antagonistic bacteria rC10-1strain was substantial declined, the biocontrol agent behaved inhibitory action. As the change of time, the number made a comeback finally the number of pathogenic fungus in all disposed sick soil tended to be stable, thus, that instructed the Bacillus amyloliquefaciens rC10-1strain has a inhibitory action on the pathogenic fungus in the soil, and the inhibition has a certain cycle.To study the colonization and prevention effect of the marked, antagonistic bacillus r C10-1strain in rhizosphere, root table and within the root, as well as the distribution in the different soil depth of banana plant. Using the root irrigation method to inoculate the test Bacillus amyloliquefaciens strain C10-1in the potted banana plant, the banana plant were disposed by pathogenic fungus and sterile water. It demonstrated that the tested strain C10-1could effectively control the occurrence of Fusarium oxysporum f.sp. Cubense, the potted antagonistic efficiency of B. amyloliquefaciens C10-1strains is66.68%. Which represented a fine colonization ability in the soil, roots and internal of banana plant. The number of B. amyloliquefaciens C10-1strains in banana rhizosphere soil will decrease with time prolonging, and the colonization rule of B. amyloliquefaciens C10-1strain in the natural soil is the same as the rule in the sick soil. At different depths of soil layer can detect the presence of antagonistic bacteria C10-1strain, it showed that the bacteria not only can colonization in the root surface, but also can spread to rhizosphere. Moreover, the B. amyloliquefaciens C10-1strain also has a strong ability of colonization on the roots of banana plant.Based on the Fusarium oxysporum f.sp. Cubense confrontation of antagonism and chitosan hydrolysis tablet, antibiotics marker screening, prevention and control of soil and potted plant experiment, we could get the B. amyloliquefaciens C10-1strain which can prevent and cure the fusarium wilt caused by Fusarium oxysporum f.sp. Cubense race4was isolated from the wetlands of East village port of mangroves. Also found the B. amyloliquefaciens C10-1strain has prevention efficiency and strong capacity of producing chitosan degradation enzyme, good colonization ability in soil and plant. All that results lay a good foundation for the large number of fermentation of the strain in the future and the prevention of banana fusarium wilt on the field application. |
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