苹果枝条内生菌longA的鉴定及其抑菌作用机理初探

Identification of the endophytic strain longA from apple twig and its antifungal mechanism against Valsa mali

摘要:

【目的】鉴定一株分离自苹果健康枝条的内生菌longA，对其抑菌作用机理进行初步探究。【方法】通过生理生化性质测定和16S rRNA基因序列分析对其进行鉴定；采用平板对峙法检测longA对苹果树腐烂病菌(Valsa mali)菌丝生长的影响和对孢子萌发的抑制作用，利用透射电镜观察苹果树腐烂病菌的细胞内部变化。【结果】16S rRNA基因序列分析结果表明该菌株为解淀粉芽孢杆菌Bacillus amyloliquefaciens；菌株longA好氧，可利用葡萄糖、蔗糖、甘露醇、乳酸、柠檬酸等碳源；耐盐性差(不能耐受质量分数7%的氯化钠)；接触酶反应呈阳性；可还原硝酸盐；能使明胶液化、水解淀粉；不能利用柠檬酸盐；乙酰甲基甲醇(V-P)试验为阴性。longA能显著地降低苹果树腐烂病菌分生孢子的萌发率，并导致其菌丝生长过程中分枝增多、顶端膨大及细胞质外渗。【结论】菌株longA能有效抑制苹果树腐烂病菌等，具有一定的生防潜能。

Abstract:

[Objective] To identify one endophytic strain longA which was isolated from healthy apple tree branches and study its antifungal mechanism. [Methods] Strain longA was identified based on the biochemical characteristics and 16S rRNA gene sequence analysis. The inhibitory efficiency of longA on the hyphal growth and conidial germination of V. mali were investigated by confrontation culture on slides. [Results] Strain longA was defined as Bacillus amyloliquefaciens. It could reduce the germination rate of spore and induce changes of mycelia morphology of V. mali significantly, such as deformity, branch increasing and cytoplasm exosmosis. Strain longA was aerobic. It could use glucose, sucrose, mannitol, lactic acid and citric acid as carbon source. Tolerates concentrations of NaCl up to 7%. Catalase reaction was positive. It could reduce nitrate, liquefy gelatin and degrade starch. It could not use citrate as the sole carbon source for growth. V-P test was negative. [Conclusion] Strain longA showed a certain potential of bio-control in the inhibition of V. mali.