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【目的】了解棉花内生细菌数量动态,从棉花中获得拮抗黄、枯萎病菌的内生细菌资源【方法】对棉花根、茎、叶表面灭菌,采用稀释平板法分离棉花内生细菌;通过对峙培养法体外鉴定分离的棉花内生细菌对棉花黄、枯萎病菌的拮抗作用,并对拮抗棉花黄、枯萎病菌的内生细菌16SrDNA序列进行了分析【结果】棉花根中内生细菌的数量显著高于茎、叶;根的苗期总体内生细菌数量低于开花期、吐絮期,茎、叶中的内生细菌数量在不同生育期呈现一定的波动性,但趋势性不明显;6个棉花品种根中内生细菌平均数量差异并不显著,但茎、叶中内生细菌数量不同品种间呈现一定程度差异。平板对峙鉴定显示:棉花根中具有较高比例的拮抗棉花黄、枯萎病菌的内生细菌,拮抗强致病落叶型黄萎病菌(V107)的内生细菌比例不仅低于枯萎病菌(F108),而且低于非落叶型黄萎病菌(V396)。同时拮抗棉花黄、枯萎病菌的内生细菌有44株,16SrDNA分子序列分析表明:这些拮抗内生细菌的类群包括了两个门(变形杆菌门、拟杆菌门)8个属,其中10个菌株与已报道菌株相似性<97%,可能是新的种(属),优势种群为肠杆菌属(18株)、泛菌属(15株)。【结论】棉花的品种、生育期与器官影响棉花内生细菌数量;棉花拮抗黄、枯萎病菌的内生细菌具有优势种群,且具多样性。
【Objective】 The objective of this study was to understand the dynamic changes of endophytic bacteria in cotton and to obtain endophytic bacteria that antagonize the pathogen of yellow and Fusarium wilt from cotton. 【Method】 Endophytic bacteria were isolated from the roots, stems and leaves of cotton by using dilution plate method. The antagonistic effects of endophytic bacteria isolated from cotton in vitro on cotton yellow and Fusarium oxysporum were identified by confrontation culture method. The endophytic bacteria 16S rDNA sequences that antagonized cotton yellow and Fusarium oxysporum were analyzed. 【Result】 The number of endophytic bacteria in cotton roots was significant The number of endophytic bacteria in the seedling stage was lower than that in the flowering stage. The number of endophytic bacteria in the boll-opening, stems and leaves showed some fluctuation at different growth stages, but the trend was not obvious. Six The average number of endophytic bacteria in cotton roots was not significantly different, but the number of endophytic bacteria in stems and leaves showed some differences among different varieties. Plaque identification showed that endophytic bacteria antagonistic to cotton yellow and Fusarium oxysporum were higher in cotton roots, and endophytic bacteria antagonistic to Verticillium dahliae (V107) were not only lower than F108, But also lower than non-deciduous Verticillium dahliae (V396). There were 44 endophytic bacteria that antagonized cotton yellow and Fusarium oxysporum simultaneously. The sequence analysis of 16S rDNA showed that these two groups of antagonistic endophytic bacteria included 8 genera (Proteus and Bacteroidetes), of which 10 strains Similar to the reported strain <97%, may be a new species (genus), the dominant species of Enterobacter (18 strains), Pantoea (15 strains). 【Conclusion】 The number of endophytic bacteria in cotton is affected by the varieties, growth stages and organs of cotton. Endophytic bacteria that antagonize yellow and Fusarium oxysporum have the dominant populations and have diversity.