水稻纹枯病拮抗细菌7-5的鉴定及其生防机制初步研究

Identification of Strain 7-5, Antagonistic to Rice Sheath Blight, and Preliminary Study of Its Biocontrol Mechanism

【目的】旨在获得对水稻纹枯病有生防效果的拮抗细菌,探索生防细菌作用机理。【方法】通过苗期防病试验从本实验室保存的7株拮抗细菌中筛选对水稻纹枯病有较好防病效果的菌株。结合生理生化性状和16S r DNA基因序列同源性分析,对生防细菌7-5进行初步鉴定,并通过PCR扩增、薄层层析等探讨7-5产生抗生素的种类。【结果】供试7株细菌中7-5、4-74和4-78对水稻纹枯病防效分别可达69.0%、70.8%和75.4%。其中4-74和4-78抑菌谱窄,7-5对水稻纹枯病菌、桃褐腐病菌和草莓灰霉病菌都具有较强抑菌能力。菌株7-5鉴定为绿针假单胞菌;该菌株可产生吩嗪-1-羧酸、嗜铁素、氢氰酸、蛋白酶、藤黄绿脓菌素和2,4-二乙酰基间苯三酚等抗菌物质,不产生硝吡咯菌素、几丁质酶和纤维素酶。【结论】绿针假单胞菌7-5主要通过产生抗生素防治水稻纹枯病。

【Objective】The objective is to obtain antagonistic bacteria for biocontrol on rice sheath blight and reveal the biological control mechanism. 【Method】The control experiment of rice sheath blight by seven antagonistic bacteria stored in our lab was performed using pot cultures at the seedling stage. The strain 7-5 was identified based on a 16S rDNA BLAST and the strain’s physiological and biochemical characterization. The antifungal compounds produced by bacterial strain 7-5 were detected by PCR amplification and thin layer chromatography （TLC）. 【Result】 The suppressive effects of bacteria 7-5, 4-74 and 4-78 on the rice sheath blight in a greenhouse were as high as 69.0%, 70.8% and 75.4%, respectively. Strain 7-5 could strongly inhibit the growth of Rhizoctonia solani, Monilinia fructicola and Botrytis cinerea, whereas both strains 4-74 and 4-78 had narrow inhibitory spectra. Strain 7-5 was identified as Pseudomonas chlororaphis and produced many antifungal factors, including phenazine-1-carboxylic acid, 2,4-diacetylphloroglucinol, pyoluteorin, siderophores, hydrogen cyanide and extracellular proteinase, but not including pyrrolnitrin, chitinase and cellulase. 【Conclusion】The production of antibiotics plays a key role for P. chlororaphis 7-5 to control the rice disease.