The Study On Control Effect Of Biocontrol Strain FJAT-346 Against Fusarium Wilt In Banana

Fusarium wilt, caused by Fusarium oxysporum f.sp.cubense(FOC), was a devastating disease of banana, threatening the safety of banana production in China and the worldwide. The endophytic bacteria strain FJAT-346 was isolated from banana plant as a biological control agent against FOC. At present research, the bacteric stain FJAT-346 was firstly tested in terms of its activity in inhibiting the mycelial growth of FOC and the toxicity to animals. Secondly, the colonization of endophytic bacteria FJAT-346 in the tissue culture and potted seedlings of banana was observed. After that, effect of endophytic bacteria FJAT-346 on enzyme activity in banana plant was studied. At last, the control efficacy of strain FJAT-346 against FOC was evaluated in pot- and field-grown banana sets.The results showed that bacteria strain FJAT-346 was safe with low toxicity to tested mouses . The inhibition rate of the endophytic bacteria strain FJAT-346 against FOC strain, FJAT-370, was 67.57%. The diameter of inhibition zone was 2.47 cm, and the inhibition rate of spore germination was 71.50%. Using antibiotics rifampin and kanamycin to mark strain FJAT-346, a stable double-antibacterial strain was obtained and performed both 300μg/ml resistances for the two antibiotics. The growth curve and the inhibition effect of the stable double-antibacterial strain of FJAT-346 were consistent with those of the wild strain. The biocontrol strain FJAT-346 could colonize in the banana plant by both root inoculation and stab inoculation. The largest quantity of FJAT-346 was colonized in bulb of tissue culture banana, and then was root and pseudostem; the least quantity of FJAT-346 was colonized in leaf of tissue cultured banana, the optimum concentration of inoculation was 105cfu/ml; The largest quantity of FJAT-346 was colonized in root of potted banana, and then was stem. The least quantity of FJAT-346 was colonized in leaf of potted banana, the optimum concentration of inoculation was 109cfu/ml.The biocontrol strain FJAT-346 could significantly increase the activity of polyphenol oxidase (PPO)in banana, but had no obvious influence on activity of superoxide dismutase (SOD), peroxidase (POD)and catalase(CAT).The control efficiency of FJAT-346 against the Fusarium wilt of potted banana plants was 83.67%, and FJAT-346 could remarkably improve the plant height and the leaf quantity of banana, but had no obvious influence on the banana root-shoot ratio. The biocontrol strain FJAT-346 could colonize in rhizosphere soil of banana, and the most quantity of colonization was 107cfu/g after 7 days of inoculation, but had no significant effect on the main rhizosphere bacterial communities of field banana. The control efficiency of FJAT-346 against the Fusarium wilt of field banana plants was 82.00%.