一株高效拮抗向日葵菌核菌的细菌菌株YC16的筛选及其作用效果研究

目的]筛选高效拮抗向日葵菌核菌的细菌菌株,为开发防治菌核菌病害、提高向日葵产量的生物菌剂提供菌种资源。方法]以羧甲基纤维素钠(CMC)、小麦秸秆纤维素为唯一碳源的无机盐培养基,分离高效降解纤维素的细菌菌株;采用纤维素降解菌与菌核菌的平板对峙方法,进一步筛选拮抗菌核菌的菌株;利用16S rDNA序列鉴定菌株、PDYA平板对峙实验检验上述所选拮抗菌株的抑菌谱;采用离体向日葵新鲜叶片、草炭土基质盆栽实验,观察拮抗菌菌株抑制菌核菌生长的能力;温室盆栽和田间试验条件下,研究其防治向日葵菌核菌病害、促进生长和提高产量的效果。结果]筛选了一株高效抑制菌核菌的细菌YC16,经过16S rDNA序列分析,鉴定为解淀粉芽孢杆菌。YC16菌株能够抑制8种病原真菌生长,包括齐整小核菌、腐皮镰孢菌、尖孢镰刀菌、稻梨孢、辣椒疫霉、镰刀菌、尖镰孢黄瓜专化型和向日葵菌核菌;抑制菌核菌感染叶片,抑制率达到了80.42%;抑制盆栽基质中菌核菌的菌丝生长,基质表面菌丝密度比对照减少了50%以上。盆栽接种YC16的向日葵生物量比对照提高54.9%,田间向日葵接种YC16菌剂对菌核菌引发的盘腐病防治效果达39%-100%,产量提高24.4%-30.2%。结论]YC16生物菌剂施用于土壤,能够有效防治向日葵的茎腐病和盘腐病,展现了防治向日葵菌核病和提高产量的双重效果,是一株具有良好应用前景的高效菌种资源。

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

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.