Isolation of a high effective antagonistic bacterial strain YC16 against Sclerotinia sclerotiorum diseases in sunflower

Abstract:

[Objective] To isolate antagonistic bacteria against Sclerotinia sclerotiorum diseases in sunflower. [Methods] Cellulose-degrading bacteria were isolated by CMC and wheat straw cellulose as sole carbon and energy source in mineral culture medium, then the ability of cellulose-degrading bacteria to suppress Sclerotinia sclerotiorum mycelium development was recorded under various conditions. The antagonistic spectrum of the isolate YC16 against pathogenic fungi was tested on PDYA petri-dishes, the suppressive ability of YC16 against Sclerotinia sclerotiorum was also observed using fresh detached leaves of sunflower and peat pot experiment. The effect of YC16 inoculation on plant growth promotion and Sclerotinia rot diseases prevention of sunflower was studied in pot and field experiment. [Results] YC16 was isolated and identified as Bacillus amyloliquefaciens. YC16 could suppress eight pathogenic fungi, including Sclerotium rolfsii, Fusarium solani, Fusarium oxysporum, Pyricularia oryzae, Phytophthora capsici, Fusarium sp., Fusarium oxysporum f. sp. cucumerinum Owen and Sclerotinia sclerotiorum. YC16 could inhibit S. sclerotiorum from infecting sunflower leaves by 80.42% and reduce the density of S. sclerotiorum mycelia by more than 50% on the surface of the Peat media compared with the control under pot condition. YC16 inoculation increased obviously the fresh biomass weight of sunflower by 54.9%. Under conventional chemical fertilizer application, YC16 inoculation increased sunflower yield by 24.4% to 30.2%, S. sclerotiorum diseases of sunflower was reduced by 39% to 100% through 3 year's field studies. [Conclusion] The isolate YC16 showed the potential for controlling sunflower Sclerotinia rot diseases and increasing sunflower yields as an efficient microbial resource for development of biocontrol agent.