利用诱捕法从土壤中分离得到18株木霉(Trichoderma sps.)菌株,采用对峙法从中测定、筛选出一株对烟草赤星病菌(Alternaria alternata)具有极强拮抗作用的菌株(Tv-1).光学显微镜及透射电镜观察结果表明,Tv-1菌株的拮抗机制主要为生长竞争、寄生作用以及产生抗菌素类物质使病菌菌丝消解,表现为Tv-1菌株菌丝生长迅速;能附着、缠绕于病菌菌丝上,并产生吸器侵入菌丝;同时还能分泌使病菌菌丝原生质浓缩、断裂、消解的物质.%By the method of baiting,18 isolates were obtained,and further identificatied as Trichoderma viride.The antagonistic tests of all these isolates to 7 strains of Alternaria alternata from diseased tobacco leaves from different area of Yunnan were carried out by pairing culture on PDA.The results showed that 1 isolated (Tv-1) was strong antagonistic.The examination of antagonistic mechanism under optical microscope and transmission electron microscope showed Tv-1 hyphae growed quickly.Its hyphae could adhere to,coil around the hyphae of pathogen.Its finger-shaped haustorium penetrated into the hyphae of Alternaria alternat.Tv-1 could also secret antibiotic substance to make the pathogan hyphal plasma contracted,vacuolated and disrupted.
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