黄瓜枯萎病拮抗放线菌筛选及其生防作用鉴定

 通过高效筛选法从不同环境采集的土样中分离出44株对黄瓜枯萎病菌有拮抗作用的菌株，通过平板对峙法初筛和复筛得到一株具有较高拮抗活性的放线菌XF-7。研究了菌株XF-7发酵液对黄瓜枯萎病病原菌孢子萌发、菌丝生长及黄瓜种子发芽的影响，以及对苗期枯萎病的生防效果。结果表明：菌株XF-7发酵液对黄瓜枯萎病菌的菌丝生长及孢子萌发均有明显的抑制作用，可促进黄瓜种子发芽，且对黄瓜苗期枯萎病的防治效果显著，防效达79.57%。经16S rDNA序列分析，发现菌株XF-7与毒三素链霉菌（Streptomyces toxytricini）的16S rDNA序列同源性达100%。结合形态特征和生理生化特性，将菌株XF-7鉴定并命名为Streptomyces toxytricini XF-7，在GenBank中该菌株的序列登录号为JN315670。

Isolation and Identification of Antagonistic Actinomycetes and Their Application in the Biocontrol of Fusarium oxysporum f. sp. cucumerinum

To obtain antagonistic actinomycetes against plant pathogen,Fusarium oxysporum f.sp.cucumerinum,about 44 strains of actinomycetes with antagonistic activity were isolated from various soil samples.Through the primary and secondary screening,the strain XF-7 showed the most efficient antagonistic activity among all tested strains.Moreover,the effects of fermentation broth of strain XF-7 on mycelium growth,spore germination of F.oxysporum f.sp.cucumerinum,seed germination of cucumber were tested,and the clay-pot experiments on the biocontrol effects of fermentation broth on seedling fusarium wilt were conducted.The results indicated that the fermented broth of strain XF-7 had a significant inhibition on the mycelium growth and spore germination of plant pathogen,and had a stimulative effect on seed germination of cucumber,the control efficacy against seedling fusarium wilt of cucumber was significantly up to 79.57% as compared to the control.The 16S rDNA sequence of strain XF-7 shared 100% homology with Streptomyces toxytricini,strain XF-7 was morphologically and molecularly identified and named as S.toxytricini XF-7,with GenBank accession number JN315670.