摘要：本研究通过平板稀释法、平板对峙法从核桃根部皮层筛选出一株对核桃根腐病有拮抗作用的内生菌株1A，通过形态特征测定、理化特性分析和16S rDNA 序列分析鉴定该菌为芽胞杆菌（Bacillus sp.），GenBank序列登录号为KJ865856；其抑菌特性研究结果表明：该拮抗菌对核桃根腐病菌有显著的抑制效果，抑菌率达63.33%；此外，该菌對板栗疫病菌等几种不同的林木病原菌均有较强的抑制作用。抗生机理研究结果表明，该菌株通过分泌蛋白酶和纤维素酶降解真菌细胞壁中蛋白质和纤维素，破坏病菌菌丝，病菌生长受到抑制。该拮抗菌能够显著抑制核桃根腐病菌菌丝生长和孢子萌发，孢子萌发抑制率达74.89%，病菌菌丝表现为菌丝扭曲、断裂，分支增多并缠绕，菌丝颜色加深等。盆栽生防效果研究显示，该拮抗菌对各组核桃根腐病具有显著的防治效果，采用该拮抗菌预处理具有相对较好的生防效果。
关键词：核桃根腐病；腐皮镰刀菌；内生细菌；芽胞杆菌；抗菌机理
中图分类号：S 476文献标识码：ADOI：10.3969/j.issn.05291542.2016.01.006Isolation， identification and antimicrobial mechanism of an
endophytic antagonistic bacteriumLiu Yang1，Zhu Tianhui1，Zheng Lei1，Zhang Jing1，Lan Haoyang2，Guo Zhibin3（1. Forestry College of Sichuan Agricultural University， Ya’an625014， China； 2. Forestry and
Landscape Bureau of Chaotian District of Guangyuan， Sichuan Province， Guangyuan628000， China；
3. Forestry and Landscape Bureau of Guangyuan， Sichuan Province， Guangyuan628000， China）AbstractThe endogenic bacterium strain 1A from walnut root was found to have antagonistic effect on Fusarium solani. Strain 1A was identified as Bacillus sp. based on the observation of morphological features， the analysis of physiological and biochemical characteristics， and the 16S rDNA sequences. The GenBank accession number was KJ865856. The antimicrobial research results showed that strain 1A had a significant inhibitory effect on F.solani and the inhibition rate reached to 63.33%. In addition， strain 1A had a significant inhibitory effect on several forest pathogenic bacteria such as Cryphonectria parasitica. The result of antibiosis mechanism indicated that strain 1A could produce protease and cellulase to degrade the protein and cellulose composition of fungal cytoderm， and damage F.solani mycelia to inhibit the growth of F.solani. The strain 1A could strongly inhibit the hyphal growth and spore germination of F.solani， and the inhibition rate of spore germination was 74.89%. The mycelia were distorted， fractured， with increased and winding branches and deepened color. The antagonistic bacterium strain 1A showed good control potential against walnut root rot in the semifield experiment and the pretreatment of the antagonistic strain 1A had a better biocontrol effect.
Key wordswalnut root rot；Fusarium solani；endophytic bacterium；Bacillus sp.；antimicrobial mechanism 核桃（Juglans regia L.） 是我国重要的“木本粮油”树种，含有大量对人体健康有益的营养成分，被认为是“21世纪的超级食品”[1]。核桃根腐病是威胁核桃生产的重要病害之一，在核桃种植区发病率较高。相较于化学防治，生物防治对人、畜及植物安全，不污染环境，对病害有持久的控制作用，是未来病虫害防治的发展方向[23]。目前，关于核桃根腐病生物防治有待进一步研究。一些植物内生菌与宿主植物发生关系时，可明显增强植物的抗病性，促进植物的生长[4]。李桂霞等从感染灰霉病的番茄大棚土壤中分离到6株拮抗细菌，其中蜡样芽胞杆菌B02和枯草芽胞杆菌B06对灰霉病菌有很强的抑制作用，将发酵液稀释不同倍数之后仍然具有很好的抑菌作用[5]。芽胞杆菌（Bacillus）是土壤和植物微生态的优势菌群，可以产生抗逆性芽胞，可耐受各种不良环境，有效活菌数高，性能稳定，成为理想生防菌的筛选对象而备受青睐[67]。本研究主要以核桃根腐病病菌（Fusarium solani）为指示菌，筛选鉴定出对其有拮抗作用的内生细菌，探讨防病作用机制及防治效果，为进一步研发对根部腐烂病害有良好防治作用的生物农药奠定理论基础。
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