番茄青枯病生防链霉菌的分离鉴定及生物学特性

Isolation, identification, and biological characterization of Streptomyces strains against tomato bacterial wilt

摘要:

由青枯劳尔氏菌(Ralstonia solanacearum)引起的番茄青枯病，严重影响番茄的产量和品质，给番茄种植业带来了巨大的经济损失和挑战。目的 实现链霉菌对番茄青枯病的高效生物防治，为生防链霉菌菌剂的开发提供理论基础。方法 从土样中筛选出6株对青枯劳尔氏菌具有良好抑菌效果的放线菌(AB_1-AB_6)。分别对菌株进行形态、生理生化和分类鉴定，分析菌株的多种胞外酶活性及根际定殖能力，并进一步通过温室盆栽试验评估菌株对番茄青枯病的生防效果。结果 六株放线菌对青枯劳尔氏菌的抑菌圈范围为1.76-6.76 cm。经16S rRNA基因序列比对发现，6株放线菌均属于链霉菌属，其中菌株AB_1与Streptomyces gardneri相似度为98.67%，AB_2与S. pratensis相似度为97.59%，AB_3与S. diastatochromogenes相似度为97.33%，AB_4与S. canus相似度为96.54%，AB_5与S. albiflavescens相似度为96.94%，AB_6与S. gramineus相似度为97.34%。盆栽试验结果显示6株链霉菌对番茄青枯病的防效达到69.23%-100.00%。6株链霉菌均能良好地定殖于番茄根际，且具有多种胞外酶活性，如酯酶、淀粉酶、脲酶等，同时也具有广泛的碳氮源利用能力，较强的pH和盐耐受能力等。结论 六株链霉菌具有良好的环境适应性及番茄根际定殖能力，且对番茄青枯病均展现出良好的盆栽防控效果。本研究结果符合农业绿色发展理念并为链霉菌在番茄青枯病的防治和管理过程中提供了实验基础与理论依据。

关键词:番茄青枯病;链霉菌;抑菌活性;生防效果

Abstract:

Tomato bacterial wilt caused by Ralstonia solanacearum seriously affects the yield and quality of tomato and brings serious economic losses and challenges to the tomato planting industry.Objective To achieve efficient biocontrol of tomato bacterial wilt by Streptomyces, providing a solid theoretical foundation for the development of biocontrol agents.Methods Six biocontrol strains of actinomyces (AB_1 to AB_6) exhibiting potent inhibitory activities against R. solanacearum were isolated from soil samples. The morphological, physiological, biochemical, and taxonomical characteristics of these strains were determined. Additionally, the extracellular enzyme activities and rhizosphere colonization abilities of the strains were analyzed. Furthermore, a greenhouse pot experiment was conducted to evaluate the biocontrol efficacy of these strains against tomato bacterial wilt.Results The inhibitory zone diameters of the strains against R. solanacearum ranged from 1.76 cm to 6.76 cm. Comparative analysis of the 16S rRNA gene sequences revealed that all the six strains belonged to the Streptomyces. The sequence similarities between strain AB_1 and Streptomyces gardneri, AB_2 and S. pratensis, AB_3 and S. diastatochromogenes, AB_4 and S. canus, AB_5 and S. albiflavescens, and AB_6 and S. gramineus were 98.67%, 97.59%, 97.33%, 96.54%, 96.94%, and 97.34%, respectively. Pot experiments demonstrated that these six Streptomyces strains prevented tomato bacterial wilt with the efficacy ranging from 69.23% to 100.00%. All the six strains successfully colonized the tomato rhizosphere and exhibited activities of diverse extracellular enzymes including esterase, amylase, and urease. Additionally, they displayed extensive utilization of carbon and nitrogen sources along with robust tolerance towards variations in pH and salt concentrations.Conclusion The six strains of Streptomyces exhibited remarkable environmental adaptability and demonstrated efficient colonization in the tomato rhizosphere. Moreover, they displayed potent antagonistic activity against tomato bacterial wilt in pot experiments. These findings align with the principles of sustainable agriculture and provide both theoretical and experimental evidence for utilizing Streptomyces as a preventive and management strategy against tomato bacterial wilt.

Key words:tomato bacterial wilt;Streptomyces;antimicrobial activity;biocontrol effect