Abstract:An endophytic biocontrol bacterium FJAT-346-PA, which was isolated from banana and identified as Pseudomonas aeruginosa, showed high inhibition on mycelial growth of Fusarium oxysporum f.sp.cubense. In order to study the colonization characteristic of FJAT-346-PA inside the plant, an antibiotic-marked experiment was conducted to screen stable antibiotic-marked strain by enhancing the inducing concentration of antibiotic gradually. A double antibiotic-marked strain FJAT-346-PA-K was obtained while the inducing concentration of antibiotic rifampicin and kanamycin were both at 300 μg/mL. After that, the colonization of antibiotic-marked strain FJAT-346-PA-K inside the tissue-culturing seeding, pot-culturing seeding and field plant of banana were analyzed. Meanwhile, the effect of the biocontrol agent on the plant growth and its control efficiency against banana Fusarium wilt banana were also investigated. The results showed that FJAT-346-PA-K could colonize in the roots and stems of banana, with maximum of 2.15×105 CFU/g and 8.00×103 CFU/g at roots of pot-culturing seeding and filed plant, respectively. FJAT-346-PA-K was also found to promote the plant growth remarkably by increasing the plant height and the leaf number. The endophytic biocontrol bacterium performed good control potential against banana Fusarium wilt disease with control efficiencies of 83.67% in the semi-field experiment and 82.00% in the field experiment.