[目的]从桃树根部组织中分离、筛选能够防治桃褐腐病害的内生拮抗菌,从细胞学水平探究其抑制机理.[方法]采用平板对峙法筛选对桃褐腐病菌(Monilinia fructicola)有拮抗作用的内生细菌,调查内生拮抗细菌的形态学及生理生化特性,通过细菌16S rRNA基因测序分析菌株的系统发育学特征.通过果实离体实验检测内生拮抗细菌的抗菌效果,使用电子显微镜观察受抑制的桃褐腐病菌菌丝、孢子的形态以及细胞内部结构变化.[结果]从桃树根部组织中复筛分离得到的3株内生细菌对桃褐腐病防效高且稳定,经鉴定3株细菌均为枯草芽孢杆菌.果实离体试验表明,3株内生细菌均明显抑制了桃褐腐病的发生.通过电子显微镜观察,发现受拮抗细菌抑制的桃褐腐病菌的菌丝明显变细、杂乱且打结缠绕成团,孢子普遍干瘪变大、破裂,细胞质外渗.[结论]从桃树根部组织中得到的3株内生细菌对桃褐腐病菌的生长均有明显的抑制作用,可以作为防治桃褐腐病的新选择,具有进一步研究价值.%[Objective] Antagonistic endophytic bacteria against Monilinia fructicola were screened from the roots of peach trees.The inhibitory mechanism was studied at cellular level.[Methods] The confront-culture method was adopted to screen endophytic bacteria against M.fructicola.The obvious features of antagonistic strains were determined by cell morphological observation,physiological and biochemical characteristics.Strains were identified by 16S rRNA gene sequencing and phylogenetic analysis.The effect of biological control was tested through the experiment of fruits in vitro.The change of mycelia,spore morphology and the internal structure of cells was observed under electron microscope.[Results] By secondary screening,three strains had obvious and stable effect antagonist M.fructicola,these strains were identified as Bacillus subtilis.The experiment of fruits in vitro showed that the three strains inhibited the growth of M.fructicola obviously.Results of microscopic analysis show that the mycelia inhibited by the antagonistic bacteria were obviously attenuated,with severe disorder,twining and knotting.Most spores were shriveled,enlarged and rupture.In cells of the pathogen inhibited by the antagonistic bacteria,the phenomena of cytoplasm exosmosis,protoplast shrinkage and condensation,and a large amount of cavities were observed.[Conclusion] The three strains of the endophytic bacteria screened from the roots of peach trees had effective inhibitory on the growth of M.fructicola,these strains could be served as new resources against M.fructicola.
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