Abstract:
Objective To isolate and screen antagonistic bacteria from healthy banana rhizosphere soil against Fusarium wilt disease.
Methods The bacterial strain antagonizing Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) was screened from banana rhizosphere soil using the plate confrontational culture method. The antagonistic strain was identified by colony morphology, physiological and biochemical characteristics, and phylogenetic analysis of multiple genes including 16S rDNA, GyrB, AtpD and GltB. The effect of this strain on Foc TR4 hyphae growth and spore germination was analyzed by microscopic observation, the antifungi spectrum was determined by the plate confrontation culture method, the biological control and growth-promoting efficiency were tested by banana plant inoculation assay in greenhouse.
Result An antagonistic strain of GD1-1 was screened with an inhibition rate of 72.5% on Foc TR4 hyphal growth and an inhibition rate of 99.8% on Foc TR4 spore germination, which was identified as Burkholderia contaminans. The strain GD1-1 could cause hyphal distortion, enlargement and malformation of Foc TR4 under microscope observation. The strain GD1-1 possessed the broad-spectrum antibacterial activity with a good inhibitory effect on the selected ten phytopathogenic fungi. The results of pot inoculation experiment showed that the strain GD1-1 successfully promoted the growth of banana seedlings and suppressed the incidence of banana Fusarium wilt with a biocontrol efficacy of 55.6%.
Conclusion The strain GD1-1 has the significant inhibitory effect on Foc TR4 with a good control effect on banana wilt disease, and promotes the growth of banana plant. As a high-quality source of biocontrol bacteria, strain GD1-1 has certain potential for development and application.
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