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目的:筛选出对辣椒疫霉菌具有高效拮抗作用的木霉生防菌株,研究其对辣椒菌菌丝体和卵孢子的作用机制,评价其应用于辣椒疫病的生防潜力。创新点:首次在超微结构水平上报道棘孢木霉菌菌丝能重寄生于辣椒疫霉菌的卵孢子,为木霉生防菌的应用提供了科学理论依据。方法:从土壤中分离木霉菌株,采用对峙培养法筛选木霉生防菌株。通过形态学和多基因序列(ITS、tef1和rpb2)进行鉴定,明确获得木霉菌株的种类。通过细胞学和超微结构观察,研究木霉生防菌对辣椒疫霉菌菌丝和卵孢子的拮抗机制。结论:本研究筛选出了对辣椒疫霉菌菌丝具有高效拮抗作用的一个木霉菌株(CGMCC 6422),被鉴定为棘孢木霉菌(Trichoderma asperellum)。细胞学和超微结构显示,该菌株能塌陷辣椒疫霉菌的菌落,通过缠绕和穿透辣椒疫霉菌的菌丝体,引起菌丝体解体;首次观察到该菌株能侵染辣椒疫霉菌的卵孢子,并引起卵孢子完全降解。综上所述,筛选出的木霉生防菌株CGMCC 6422具有应用于防治辣椒疫病的生防潜力。
OBJECTIVE: To screen out Trichoderma antifungal strains with high antagonistic effect against Phytophthora capsici and to study its mechanism of action on mycelium and oospores of Capsicum, and to evaluate its biocontrol potential for pepper blight. The innovation point: for the first time at the ultrastructure level reported that the fungus spores Trichoderma re-parasitization spawn Phytophthora capsici, Trichoderma biocontrol bacteria provide a scientific theoretical basis. Methods: Trichoderma strains were isolated from soil and the biocontrol strains of Trichoderma were screened by confrontation culture method. The species of Trichoderma strains was clearly identified by morphological and polygenic sequences (ITS, tef1 and rpb2). The cytotoxicity of Trichoderma against A. capsici and oospores was studied by cytology and ultrastructure observation. Conclusion: In this study, a Trichoderma strain (CGMCC 6422) with high antagonistic activity against Phytophthora capsici was screened and identified as Trichoderma asperellum. Cytology and ultrastructure showed that the strain could collapse the colonies of Phytophthora capsici and cause the mycelium to disintegrate by twining and penetrating the mycelium of Phytophthora capsici. The strain was found to be able to infect Phytophthora capsici Spores, and cause complete degradation of oospores. In summary, the selected Trichoderma biocontrol strain CGMCC 6422 has the potential of biocontrol potential for controlling pepper blight.