棉花黄萎病拮抗促生菌筛选鉴定及其活性评价

Screening and identification of antagonistic growth-promoting bacteria against cotton verticillium wilt and evaluation of their activities

摘要:

背景 棉花黄萎病是一种对棉花产业影响极大的病害，对棉花的品质及棉农经济造成严重影响。目的 分离筛选出具有高效抗病促生性能的菌株，为棉花黄萎病的生物防治提供菌种资源。方法 采用稀释涂布平板法、平板对峙法筛选出对棉花黄萎病具有拮抗作用的菌株，结合形态学分析、生理生化检测及分子生物学鉴定菌株分类地位。对菌株进行产酶、固氮和溶磷促生能力的测定，优化培养条件，并通过棉花盆栽试验明确菌株在抑菌促生中的实际应用效果。结果 分离筛选出1株对大丽轮枝菌(Verticillium dahliae)有高效抑制作用的贝莱斯芽孢杆菌(Bacillus velezensis) F41-14，抑菌率达76.32%，吲哚乙酸(indole-3-acetic acid, IAA)产量为4.15 mg/L。菌株F41-14具有产纤维素酶、蛋白酶、淀粉酶和溶磷能力，最佳培养条件为培养时间72 h、接种量3%、温度30 ℃、初始pH 7.0。盆栽试验表明，拮抗菌能定殖在棉花根系部位，并且能促进棉花植株的生长，降低病情指数，防病效果达78.62%。结论 贝莱斯芽孢杆菌F41-14具有良好的抑菌促生潜力，可作为一种有效的生防菌株应用于棉花黄萎病的生物防治中，具有重要的实际应用价值。

Abstract:

Background Cotton verticillium wilt is a highly detrimental disease to the cotton industry, severely affecting cotton quality and the economic well-being of cotton farmers.Objective To isolate and screen strains with high-efficiency disease resistance and growth-promoting properties, so as to provide microbial resources for the biological control of cotton verticillium wilt.Methods The dilution-plating method and plate confrontation method were used to screen strains with antagonistic effects against cotton verticillium wilt. Morphological analysis, physiological and biochemical tests, and molecular biology were employed to identify the taxonomic status of the strains. The strains were assessed for enzyme production, nitrogen fixation, and phosphate solubilization capabilities. Cultivation conditions were optimized, and the practical application effects of the strains in antifungal and growth-promoting activities were evaluated through cotton pot experiments.Results A strain of Bacillus velezensis F41-14 with a high inhibitory activity against Verticillium dahliae was isolated and screened, showing an inhibition rate of 76.32% and an indole-3-acetic acid (IAA) production of 4.15 mg/L. Strain F41-14 exhibited the ability to produce cellulase, protease, and amylase and solubilize phosphate. The optimal cultivation conditions were 72 h of incubation, 3% inoculum size, 30 ℃, and initial pH of 7.0. Pot experiments demonstrated that the antagonistic strain colonized the root system of cotton, promoted cotton plant growth, reduced the disease index, and achieved a control efficacy of 78.62%.Conclusion B. velezensis F41-14 exhibits significant antifungal and growth-promoting potential, which makes it a viable biocontrol strain against cotton verticillium wilt, with substantial practical value.