拮抗两种辣椒病害的菌株鉴定及生防潜力评价

Identification and biocontrol potential of a strain against two pepper diseases

摘要:

【背景】由齐整小核菌(Sclerotium rolfsii)引起的辣椒白绢病和辣椒疫霉(Phytophthora capsici)引起的辣椒疫病，严重影响了辣椒的产量及品质。【目的】获得两种辣椒病害的高效拮抗生防细菌，为生防菌剂开发提供理论基础。【方法】从前期保存的微生物资源库中筛选到一株对两种病原菌均有良好抑制效果的菌株SEC-197。对菌株进行形态、生理生化和分子鉴定，分析其产胞外酶和植物促生特性，通过PCR扩增检测抑菌促生相关基因，并进一步通过盆栽试验评价该菌株的生防效果和促生作用。【结果】菌株SEC-197对齐整小核菌和辣椒疫霉的平板抑制率分别为76.59%±0.59%和74.85%±0.35%。经鉴定菌株SEC-197为贝莱斯芽孢杆菌(Bacillus velezensis)，该菌株可以形成生物膜，并且具有分泌蛋白酶、纤维素酶、溶解有机磷和无机磷、产铁载体以及固氮的能力，经测定菌株具有srfAB、fenB和ysnE等抑菌促生基因，盆栽试验显示该菌株对辣椒白绢病和辣椒疫病的防效分别达72.08%和70.42%，且该菌株发酵液能显著提高辣椒植株的茎宽、鲜重和干重等生长指标。【结论】菌株SEC-197对辣椒白绢病和辣椒疫病均具有显著的拮抗活性且促生效果良好。该研究结果为辣椒的生产应用提供了理论依据与试验基础。

关键词:贝莱斯芽孢杆菌;辣椒白绢病;辣椒疫病;抑菌活性;生防效果

Abstract:

[Background] Pepper southern blight caused by Sclerotium rolfsii and pepper blight caused by Phytophthora capsici have seriously affected the yield and quality of peppers (Capsicum annuum). [Objective] To obtain efficient antagonistic bacteria for the biocontrol of two pepper diseases and provide a theoretical basis for the development of biocontrol agents. [Methods] From the pre-preserved microbial resource library, the strain SEC-197 with strong inhibitory effects on both pathogens was screened out. It was identified by morphological, physiological, biochemical, and molecular analyses. The production of extracellular enzymes and plant growth-promoting effect of the strain were assessed. PCR amplification was employed to mine the genes associated with the inhibitory and promoting effects. Furthermore, the biocontrol and plant growth-promoting effects of the strain were evaluated by pot experiments. [Results] The strain SEC-197 showed inhibitory rates of 76.59%±0.59% and 74.85%±0.35% against S. rolfsii and P. capsici, respectively. Strain SEC-197 was identified as Bacillus velezensis, which can form biofilms and had the ability to secrete proteases and cellulases, dissolve organic and inorganic phosphorus, produce siderophores, and fix nitrogen. The strain carried biocontrol and growth promotion-related genes such as srfAB, fenB, and ynsE. The pot experiment results showed that the strain had the control effects of 72.08% and 70.42% against pepper southern blight and pepper blight, respectively. Moreover, the strain’s fermentation broth significantly increased growth indicators such as stem width, fresh weight, and dry weight of pepper plants. [Conclusion] The strain SEC-197 has significant antagonistic activity against both pepper southern blight and pepper blight and an obvious plant growth-promoting effect. The research finding provide a theoretical basis and experimental foundation for the practical application of pepper production.

Key words:Bacillus velezensis;pepper southern blight;pepper blight;antagonistic activity;biocontrol effect