Plant growth-promoting characteristics and control effect of antagonistic bacteria against sugarcane smut

【Objective】 To screen for bacteria with the characteristics of antagonizing sugarcane smut and promoting plant growth to provide strain resources and reference for the biological control of sugarcane smut.【Method】 The rhizosphere soils of sugarcane with serious incidences of sugarcane smut disease were collected, and antagonistic strains were isolated and purified by gradient dilution and the plate confrontation culture method. The classification of antagonistic strains was determined by 16S rRNA sequence analysis and their different growth promoting characteristics were analyzed. In parallel, their effect on sugarcane smut development was studied by pot experiments.【Result】 A total of 68 bacterial strains were obtained after isolation and purification, of which seven strains(G1, G10, G12, G14, G20, G21 and G23) had inhibitory effects on the fungus Sporisorium scitamineum. The seven strains showed different growth promoting abilities, as indicated by their differing productions of cellulose, chitinase, indole acetic acid(IAA), 1-aminocyclopropane-1-carboxylic aciddeaminase(ACC deaminase), siderophores, proteases, hydrocyanic acid production(HCN) pro-duction, and their abilities to dissolve organic phosphate. Three strains of Burkholderia spp.(G1, G10 and G23) ranked highest. The pot experiment of sugarcane smut control showed that four antagonistic strains(G1, G10, G12 and G23) effectively inhibited the occurrence of smut and improve the emergence rate and biomass of sugarcane with a significantly increase in biomass. Among all the strains, the strain G3 seemed to be the most performing one.【Conclusion】 The top seven strains displaying antagonistic effects on sugarcane smut all show different growth promoting ability. Considering all the data, the antagonistic strain G23 shows the best combined effects of smut control and growth promotion, indicating good application potential.