黄瓜根际促生菌Bacillus subtilis S1的分离鉴定与促生抗病

Isolation and characterization of Bacillus subtilis S1 capable of inducing resistance against powdery mildew and promoting cucumber growth from cucumber rhizosphere

摘要:

【背景】黄瓜白粉病作为黄瓜种植过程中常见的真菌病害之一，在世界范围内广泛发生，造成黄瓜品质和产量下降，引起严重的经济损失。【目的】分离鉴定对黄瓜白粉病具有防治效果的原始生防细菌菌株，验证其防病促生作用。【方法】利用平板筛选法分离拮抗菌，并结合使用16S rRNA基因序列分析、系统发育分析、全基因组测序、次生代谢物预测及形态特征分析等方法鉴定该菌株对黄瓜白粉病的生防效果以及对黄瓜植株生长的促进作用。【结果】利用玉米小斑病菌(Bipolaris maydis)作为指示菌，平板筛选得到拮抗细菌S1，并验证该菌对盆栽种植黄瓜植株的促生作用以及对白粉病的防治效果。16S rRNA基因序列分析结果表明该菌株与Bacillus subtilis KZH-E3具有100%的相似性。通过全基因组测序，借助生物信息学分析工具，利用系统发育进化关系，在全基因组水平上菌株S1被鉴定为枯草芽孢杆菌，自主命名为Bacillus subtilis S1。通过温室盆栽防效试验，证明菌株S1对黄瓜白粉病具有显著的防效。【结论】枯草芽孢杆菌S1对黄瓜幼苗具有明显的防病促生作用，具有重要的研究意义。

关键词:黄瓜;黄瓜白粉病;分离鉴定;Bacillus subtilisS1;16S rRNA基因

Abstract:

[Background] As one of the major fungal diseases in cucumber production, powdery mildew occurs widely in the world, resulting in declined cucumber quality and yield and causing serious economic losses. [Objective] To isolate and identify the original strains for biocontrol against cucumber powdery mildew and to verify their biocontrol and plant growth-promoting effects. [Methods] Multiple methods including plate screening, 16S rRNA gene sequencing, phylogenetic analysis, whole genome sequencing, secondary metabolite analysis, and morphological characterization were employed to isolate, identify, and characterize the strains. [Results] An antagonistic bacterium S1 was obtained from the rhizosphere soil of cucumber with Bipolaris maydis as the indicator strain, and its growth-promoting effect on cucumber seedlings and control effect on powdery mildew were examined by pot experiments. The blast result of 16S rRNA gene sequences showed that this strain had a nucleotide identity of 100% compared with Bacillus subtilis KZH-E3. The whole genome sequencing combined with the phylogenetic analysis eventually identified the strain as B. subtilis. The pot experiments in a greenhouse proved that S1 had a significant biocontrol effect on cucumber powdery mildew. [Conclusion] B. subtilis S1 has obvious disease-preventing and growth-promoting effects on cucumber seedlings, having important research significance.

Key words:cucumber;cucumber powdery mildew;isolation and characterization;Bacillus subtilis S1;16S rRNA gene