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    金色轮生链霉菌GD7-17的分离鉴定及对香蕉枯萎病的生防潜力

    Isolation and identification of Streptomyces aureoversilis GD7-17 and its biocontrol potential against banana Fusarium wilt

      摘要
    • 摘要:
      目的 筛选和鉴定对香蕉枯萎病具有良好防效的生防菌。
      方法 从健康香蕉根际土壤中分离微生物，采用平板对峙培养法，以尖孢镰刀菌古巴专化型热带４号小种(Fusarium oxysporum f. sp. cubense tropical race 4，Foc TR4)为靶标菌来筛选拮抗菌株；结合形态学观察、生理生化特性测定以及多基因(含16S rDNA，GyrB，RpoB和TrpB)系统发育分析，对该菌株进行鉴定；通过显微观察，分析该菌株对Foc TR4菌丝形态和分生孢子萌发的影响；利用平板对峙试验，分析该菌株的抑菌谱；采用气相色谱−质谱联用(Gas chromatography-mass spectrometry, GC-MS)，鉴定该菌株产生的挥发性气体组成；通过盆栽试验，评估该菌株对香蕉枯萎病的防效及对香蕉植株的促生作用。
      结果 本文筛选到1株对Foc TR4具有良好拮抗效果的菌株GD7-17，鉴定为金色轮生链霉菌Streptomyces aureoversilis；其对Foc TR4菌丝生长抑制率为72.1%，导致菌丝畸形；其对植物病原真菌具有广谱抑菌活性。菌株GD7-17产生的挥发性气体也可显著抑制Foc TR4菌丝生长，抑制率为76.9%；GC-MS分析发现其挥发性气体主要含有土臭素、2−甲基异莰醇等6种物质。菌株GD7-17对香蕉枯萎病的防效为58.2%，同时对香蕉植株具有显著促生作用，使其鲜质量增加了18.0%，球茎直径增加8.2%，株高增加16.7%。菌株GD7-17还具有降解木质素、产生蛋白酶和分解无机磷等能力。
      结论 金色轮生链霉菌Streptomyces aureoversilis GD7-17对香蕉枯萎病具有良好的生防潜力，研究为香蕉枯萎病生物防治提供了潜在资源。

       

      Abstract:
      Objective To screen and identify effective biocontrol agent against banana Fusarium wilt.
      Method Antagonistic bacteria against Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) were screened from the rhizosphere soil of healthy banana plants by plates confrontation method. The antagonistic strain was identified by morphological observation, physiological and biochemical tests, and phylogenetic analysis of multiple genes including 16S rDNA, GyrB, RpoB and TrpB. The effect of the antagonistic strain on Foc TR4 hyphae morphology and conidial germination was evaluated using microscopic examination, and its antifungal spectrum was investigated by the plate confrontation method. Volatile organic compounds (VOCs) from the antagonistic strain were analyzed through gas chromatography-mass spectrometry (GC-MS). The biological control effect and plant growth-promoting effect were evaluated by pot experiments under greenhouse conditions.
      Result A strain, designated GD7-17, was isolated and identified as Streptomyces aureoversilis. It exhibited strong antagonistic activity against Foc TR4, inhibiting mycelial growth by 72.19% and inducing abnormal hyphal morphology. Furthermore, the strain showed broad-spectrum antifungal activity against plant pathogenic fungi. VOCs produced by strain GD7-17 significantly inhibited fungal growth, with an inhibition rate of 76.9%. Six VOCs were identified through GC-MS, including geosmin and 2-methylisoborneol. Furthermore, S. aureoversilis GD7-17 exhibited a biocontrol efficacy of 58.2% against banana Fusarium wilt disease, and simultaneously exerted a significant growth-promoting effect on banana plants, resulting in an 18.0% increase in fresh weight, an 8.2% increase in corn diameter, and a 16.7% increase in plant height. Strain GD7-17 was able to degrade lignin, secrete proteases and solubilize inorganic phosphate.
      Conclusion S. aureoversilis GD7-17 exhibits promising biocontrol potential against banana Fusarium wilt. This study provides a potential microbial agent for biocontrol of banana Fusarium wilt.

       

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