基于营养竞争原理的大豆根腐病生防芽孢杆菌的筛选及其特性研究

利用营养竞争平板筛选法获得了可在大豆麦麸(SWB)培养基上快速生长并拮抗大豆根腐病菌Fusarium oxysporum和F.solani的芽孢杆菌菌株B006和B010。通过16S rDNA序列分析、形态观察和生理生化性状测定,将其鉴定为枯草芽孢杆菌(Bacillus subtilis)。田间小区试验结果表明,以种子处理(108cfu/mL,药种比为1∶60)和以麦麸为载体的固体菌剂土壤沟施(106cfu/g,用量195 kg/ha)B006和B010菌剂对真叶期大豆根腐病的防治效果分别为74.6%和63.5%,高于商品化学农药35%多福合剂种子处理的防效(P=0.05),大豆产量分别增加13.8%和24.0%。利用特异引物对生防功能基因的扩增结果表明,bmyB、fenD、bioA和srfAA基因以及srfAB基因簇的片段在2个菌株中均存在,而ituC基因仅存在于B010菌株中。对菌株生防功能基因的分析有助于今后高效菌株的快速筛选和对生防菌作用机制的研究。

Characterization of Bacillus strains screened via nutritional competition for biocontrol of soybean root rot disease

Two Bacillus strains B006 and B010 were screened on SWB medium plates for their rapid spreading and inhibitive ability against growth of Fusarium oxysporum and F. solani, the pathogens of soybean root rot disease. These two strains were identified as Bacillus subtilis based on 16S rDNA sequence analysis, morphology and physiological and biochemical characteristics. In field, B006 and B010 were applied as seed and furrow treatment, and showed 74.6% and 63.5% efficiency to control soybean root rot disease at seedling stage respectively, were more efficient than the treatment with 35% Duofu (P=0.05). And they increased the soybean output by 13.8% and 24.0% respectively in comparison with that gained without any treatment. The gene fragments of bmyB, fenD, bioA, srfAA and srfAB were amplified from genomic DNA of strains B006 and B010 with specific primers, while only gene ituC was amplified from strain B010. The analysis of functional genes of isolates B006 and B010 might benefit the quick selection of potentially useful biocontrol strains and understanding of the antagonistic mechanism.