广谱拮抗放线菌C28的鉴定及其对甜瓜蔓枯病的防治效果

【目的】研究放线菌C28对12种植物病原真菌的抑菌作用及对盆栽甜瓜蔓枯病的防治效果，并对该放线菌进行分类鉴定。【方法】采用琼脂块法、生长速率法研究放线菌C28对靶标病原真菌的抑菌作用；通过盆栽试验研究C28对甜瓜蔓枯病的防治效果；根据形态特征、生理生化特性及16S rDNA序列分析确定C28的分类地位。【结果】①放线菌C28对供试病原真菌具有一定的广谱拮抗性，拮抗圈直径为10.0～22.5 mm；其无菌发酵滤液对病原真菌菌丝生长具有明显的抑制作用，无菌发酵滤液原液对木贼镰刀菌（Fusarium equiseti）、层出镰刀菌（F.proliferatum）及葡萄座腔菌（Botryosphaeria dothidea）的抑菌率分别高达95.0%，90.0%及93.1%。②用放线菌C28无菌发酵滤液稀释10⁴倍处理甜瓜种子后，甜瓜胚轴、胚根长度较对照（无菌水处理）增加37.1%和12.5%；种子简明活力指数高达141.7，与对照差异显著（P<0.05）。③用C28无菌发酵滤液原液喷施处理后，甜瓜蔓枯病病情指数较对照显著下降（P<0.05），预防和治疗效果分别为42.4%和40.0%。④根据形态特征、生理生化特性及16S rDNA序列分析，将放线菌C28鉴定为球孢链霉菌球孢亚种（Streptomyces globisporus subsp.globisporus）。【结论】球孢链霉菌球孢亚种C28对多种病原真菌具有广谱拮抗性，对甜瓜蔓枯病具有良好的抑菌和生防效果，对瓜类种子萌发和生长具有一定的促进作用。

Biocontrol effect of broad-spectrum antagonistic actinomycete on melon gummy stem blight

【Objective】 This paper intends to identify the actinomycete strain C28,and to evaluate its antagonism against 12 plant pathogenic fungi and biocontrol effect on melon gummy stem blight.【Method】 Antagonistic effect of actinomycete strain C28 on the target fungi was determined using agar block method and mycelia inhibition test;Pot trial was conducted to determine the biocontrol effect of C28 against gummy stem blight on melon plants,and strain C28 was identified by way of morphological character,physiological and biochemical characteristics,as well as 16S rDNA sequence analysis.【Result】 ①Actinomycete strain C28 showed obvious antagonistic effect on the tested pathogens,with the diameters of inhibition zones ranged from 10.0-22.5 mm.The axenic culture filtrate of C28 also displayed certain inhibition on the fungal mycelia growth,the inhibition rate of C28 against Fusarium equiseti,F.proliferatum and Botryosphaeria dothidea was 95.0%,90.0% and 93.1%,respectively.②The length of melon hypocotyl and radicle were increased by 37.1% and 12.5%,respectively,and the simple vigor index highly reached 141.7,significantly different from the control(P<0.05),when treated with 104 times dilution of C28 culture filtrate.③Strain C28 also showed definite biocontrol effect on melon gummy stem blight,the disease indexes were significantly decreased by 42.4% and 40.0%,respectively,under the protective and curative conditions.④Based on morphology character,physiological and biochemical characteristics,as well as 16S rDNA sequence analysis,strain C28 was identified as Streptomyces globisporus subsp.globisporus.【Conclusion】 Streptomyces globisporus subsp.globisporus C28 showed strong pathogen inhibition and disease biocontrol effect on melon gummy stem blight,as well as promotion effect on melon seeds germination and growth.