硫藤黄链霉菌St-79对水稻白叶枯病的防效和促生作用

【目的】水稻白叶枯病是水稻的主要细菌性病害之一，严重影响水稻生产。本研究获得一株有效防治水稻白叶枯病的放线菌菌株，探索其对白叶枯病的防效和促进水稻生长的作用，为生防菌的开发利用提供科学依据。【方法】利用梯度稀释涂布法、共培养法和牛津杯法筛选拮抗水稻白叶枯病菌(Xanthomonasoryzaepv.oryzae,Xoo)的放线菌菌株；通过形态特征、生理生化反应、16Sr DNA序列和系统发育树分析对其进行分类鉴定；利用共培养法分析目标菌株的抗菌谱；通过96孔板微量稀释法、扫描电子显微镜、微生物粘附碳氢化合物法等探究目标菌株的抑菌作用；通过发酵滤液浸种与菌液喷洒土壤的方法探究其对水稻生长的促进作用；利用盆栽试验探索目标菌株发酵滤液对水稻白叶枯病的防治效果。【结果】从不同生境土壤中分离出140株放线菌菌株，最终筛选得到一株对Xoo具有强拮抗活性的放线菌菌株St-79，其发酵滤液抑菌圈直径为64mm，并鉴定其为硫藤黄链霉菌(Streptomycesthioluteus)。菌株St-79对水稻细菌性条斑病菌(Xanthomonasoryzaepv.oryzicola)、大豆细菌性斑疹病菌(Xa...

Control Effect of St-79 (Streptomyces thioluteus) on Rice Bacterial Blight and Its Growth-promoting Effect

【Objective】 Rice bacterial blight (RBB) is one of the main bacterial diseases on rice, which seriously hinders rice production. The purpose of this study is to obtain an effective actinomycete against RBB and explore its biocontrol and growth-promoting effects, so as to lay a scientific basis for the development and utilization of biocontrol bacteria.【Method】 Actinomycetes against Xanthomonas oryzae pv. oryzae (Xoo) were screened by gradient dilution coating method, co-culture method and Oxford cup method. They were classified and identified by morphological traits, physiological and biochemical reactions, 16S rDNA sequences and phylogenetic-tree analysis. The antimicrobial spectrum of the target strain was analyzed by co-culture method. Antibacterial effect of the target strain was studied by 96-well microdilution method, scanning electron microscope and microbial adhesion hydrocarbon method; The promoting effect of fermentation liquid on rice growth was explored by soaking seeds and spraying soil. The control effect of fermentation liquid of the target strain on rice bacterial blight was studied in a pot experiment.【Result】 A total of 140 actinomycetes strains were isolated from soil in different habitats, and one actinomycete strain St-79 with the strongest antagonistic activity against Xoo was finally screened. The diameter of inhibition zone of fermentation liquid was 64 mm, and it was identified as Streptomyces thioluteus. The strain St-79 had antagonistic effects against Xanthomonas oryzae pv. oryzicola, Xanthomonas axonopodis pv. glycines, Xanthomonas campestris pv. campestris and Pseudomonas syringae pv. tomato. The ethyl acetate crude extract had good inhibitory effect on the growth of Xoo. The minimum inhibitory concentration of crude extract on Xoo was 8 μg/mL, and the minimum bactericidal concentration was 32 μg/mL. The observation results under a scanning electron microscopy showed that the crude extract had a strong damage effect on Xoo cells. Crude extracts can also change the permeability of Xoo cells and reduce the hydrophobicity of Xoo cells. The results of growth-promoting test showed that the fermentation liquid of St-79 could promote the growth of rice seedlings. The pot experiment results showed that the fermentation liquid of St-79 had good control effect on RBB. The relative control efficacies on Nipponbare, Yongyou 15 and Yongyou 1540 was 65.95%－87.23%, and the lesion inhibition rate were 69.85%－95.8%. The prevention effect was better than the post-disease treatment.【Conclusion】 An effective actinomycete against RBB was obtained, which had obvious inhibitory effect on RBB and could promote the germination and seedling growth of rice.