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[目的]以盆栽控病效果良好的一株植物内生细菌为材料,通过对铁载体的研究,探索其对棉花枯萎病的拮抗机制。[方法]通过蔗糖-天冬氨酸(Modified Sugar-Aspartic Acid,MSA)平板初步判断菌株是否产铁载体及其荧光特性;根据特定波长下吸光度值测定各菌株在液体MSA培养基内产铁载体活性;不同铁离子浓度下,比较其铁载体对棉花枯萎病的抑制作用;结合形态、生理生化等特征对其进行初步鉴定。[结果]该内生细菌在MSA培养基中高产的荧光铁载体对棉花枯萎病原真菌——尖孢镰刀菌(Fusarium oxysporum)具有抑制作用,随着铁离子浓度的提高对病原真菌的抑制作用减弱;初步分析确定该内生菌株属于芽孢杆菌属(Bacillus)。[结论]芽孢杆菌可以通过分泌铁载体竞争铁的吸收而抑制尖孢镰刀菌的生长。
[Objective] The purpose of this study was to explore the antagonistic mechanism of cotton leaf blight by using a plant endophytic bacterium with good disease control effect. [Method] The iron carrier and its fluorescence characteristics were determined by using Modified Sugar-Aspartic Acid (MSA) plates. The absorbance of each strain was determined in liquid MSA medium Under different concentrations of iron ions, the inhibitory effect of their iron carriers on Fusarium oxysporum f. Sp. Was compared. Morphological, physiological and biochemical characteristics were also preliminarily identified. [Result] The fluorescent iron carrier with high yield of endophytic bacteria in MSA medium had the inhibitory effect on Fusarium oxysporum, and the inhibition of pathogenic fungi was weakened with the increase of iron concentration The preliminary analysis confirmed that the endophytic strain belonged to Bacillus. [Conclusion] Bacillus can inhibit the growth of Fusarium oxysporum by competing the iron absorption of the secretory iron carrier.