瓜类植物内生真菌对3种土传病菌的拮抗作用研究

目的]了解瓜类植物内生真菌对瓜类植物常见土传病原真菌的拮抗作用.方法]对分自不同瓜类植物及不同部位的461株内生真菌分别与黄瓜枯萎病菌（Fusarium oxysporum f.sp.cucumerinum）、立枯病菌（Rhizoctonia solani）和菌核病菌（Sclerotinia sclerotiorum）3种土传病菌进行对峙培养试验,观察菌落形态和生长情况,记载抑菌带的有无和宽度,计算供试病原真菌菌落生长抑制率,分析内生真菌对3种土传病菌的拮抗作用.结果]内生真菌对供试病原真菌的拮抗作用表现为3种类型：抗生作用、基质竞争作用和寄生作用.在461株内生真菌中,共有13株对黄瓜枯萎病菌产生拮抗作用,25株对立枯病菌产生拮抗作用,64株对菌核病菌产生拮抗作用,分别占供试内生真菌菌株的2.8％、5.4％和13.9％.其中,菌株F30对黄瓜枯萎病菌的抑菌带最宽,达19.0 mm.菌株JCL24对立枯病菌的抑菌带最宽,达11.3 mm.菌株F94对菌核病菌的抑菌带最宽,达14.3 mm.对黄瓜枯萎病菌菌落生长抑制率大于70％的共3株,分别属于Nigrospora、Penicillium和Rhizoctonia属.对立枯病菌菌落生长抑制率大于70％的共11株,分别属于Alternaria、Apiospora、Bipolaris、Colletotrichum、Exserohilum和Fusarium 6个属.对菌核病菌菌落生长抑制率大于70％的共17株,均为Fusarium属.结论]部分瓜类植物内生真菌对土传病菌具有拮抗作用,主要通过抗生作用,少部分通过基质竞争和寄生作用抑制病菌生长.一些菌株对供试病菌抑制作用很强,可能具有用于瓜类植物病害生物防治的潜力.

Antagonism of Endophytic Fungi from Cucurbits against Three Soil-borne Phytopathogens

Objective ] To understand the antagonism of endophytic fungi from cucurbits against common soil-borne phyt.opathogens. Method] By using the dual culture method, we investigated the antagonism of 461 endophytic fungal strains isolated from different tissues of cucurbits a- gainst pathogens Fusarium oxysporum f. sp. cucumerinum, Rhizoctonia solani and Sclerotinia sclerotiorum, respectively. The configuration and growth status of the colonies, inhibition bands and their widths were observed and recorded. The inhibition rate of colonial growth of pathogenic fungi was calculated. Result] The antagonism of the endophytic fungi against the tested pathogens showed three types： antibiosis, competition for substrate, and mycoparasitism. Among 461 endophytie fungal isolates, there were 13 isolates showed antagonism against F. oxysporum f. sp. cucumerinum, 25 isolates against R. solani, and 64 isolates against S. sclerotiorum,accounted for 2.8%, 5.4% and 13.9%, respectively. The isolate F30 produced the widest inhibition band, 19 mm in width, against F. oxysporum f. sp. cucumerinum. The isolate JCL24 produced the wi- dest inhibition band, 11.3 mm in width, against R. solani. The isolate F94 produced the widest inhibition band, 14.3 mm in width, against S. sclerotiorum. Among the isolates produced the colonial growth inhibition rate of 70% or above against the pathogen tested, there were 3 isolates, belonging to Nigrospora, Penicillium and Rhizoctonia, respectively, against F. oxysporum f. sp. cucumerinum; there were 11 isolates, belonging to Alternaria, Apiospora, Bipolaris, Colletotrichum, Exserohilum and Fusarium, respectively, against R. solani ; there were 17 isolates, belonging to Fusarium, against S. sclerotiorum. Conclusion] Some of the endophytic fungal isolates from cucurbits possess antagonistic activity against soil- borne phytopathogens. The colonial growth of the pathogenic fungi was inhibited by means of antibiosis mainly, and competition for substrate and mycoparasitism in some cases. A few isolates showed strong antagonistic activity and may have the potential for biocontrol of cucurbit diseases.