白刺链霉菌(Streptomyces albospinus)CT205菌株固体发酵及防控草莓根腐病的研究

Study on solid fermentation of Streptomyces albospinus CT205 and biocontrol effect against strawberry root rot

[目的]为了明确草莓根腐病的致病因子,降低其发病率,从草莓病株根部分离病原菌,并研究拮抗菌白刺链霉菌(Streptomyces albospinus)CT205固体制剂对草莓根腐病的防控效果。[方法]从草莓病株根部分离出了1株病原菌Y3,采用形态观察及r DNA-ITS序列分析对病原菌Y3进行鉴定,用平板对峙培养测定拮抗菌CT205对菌株Y3的抑制作用,利用最佳固体发酵培养基及发酵条件对拮抗菌CT205进行固体发酵,通过连作致病土盆栽试验评价菌株CT205固体制剂对草莓根腐病的防控作用。[结果]初步鉴定病原菌Y3为尖孢镰刀菌(Fusarium sp.)。试验发现拮抗菌CT205对病原菌Y3的抑制作用较强,CT205固体发酵6 d,其制剂中菌含量达到2.2×109CFU·g-1。盆栽试验表明,施用CT205固体菌剂对草莓生长有一定的促生作用,对草莓根腐病的防治效果为61.18%。[结论]采用拮抗菌CT205固体制剂防控草莓根腐病具有较高的潜在应用价值。

[ Objectives ] In order to verify the causing factor of strawberry root rot and reduce the disease incidence, author tried to separate pathogenic fungus from strawberry root, and to study the effect of solid fermentation preparation of antagonistic Streptomyces albospinus CT205 ,separated from soil in early stage,against strawberry root rot. [ Methods] The pathogenic Y3, separated from straw- berry root with tissue separating methods, was identified according to morphological characteristics observed by optical microscope and rDNA-1TS sequences analysis. The PDA agar plate method was used to determine antifungal activity of S. albospinus CT205 against strain Y3. Strain CT205 was fermented with the optimized solid fermentation medium and fermentation conditions, and a pot experiment was conducted to evaluate the control efficiency of strain CT205 solid fermentation preparation against strawberry root rot with pathogenic soil from a field that had been cultivated with strawberry consecutively for several years. [ Results ] Strain Y3 was tentatively identified as Fusarium sp., and the pathogenicity of strain Y3 was validated with the Koch rule. The experiment showed that strain CT205 exhibited strong antagonistic effect on mycelium growth of test pathogen Y3. And it was discovered that the mycelium of strain Y3 deformation distorted with the presence of strain CT205 by microscopic examination. Strain CT205 was fermented for six days at 28 ℃ with the optimal medium, which was 500 g· kg^-1 wheat bran, 120 g· kg^-1 millet flour, 60 g· kg^-1 soybean meal, 120 g· kg^-1 rice bran,200 g· kg^-1 rice hull,3g· kg^-1 CaCO3 ,the ratio of material to water 1：0.8 ,pH 7.5. At the end of the fermentation,the viable count was measured,and it was found that the amount of the spores reached 2.2× 10^9 CFU· g^-1. The pot experiment showed that it promoted somewhat the growth of strawberry after using 1% solid fermentation preparation of CT205, besides,the control efficiency against root rot of strawberry reached as high as 61.18%. [ Conclusions] The solid fermentation preparation of S. albospinus CT205 has better potential for the control of strawberry root rot. But there are some differences between pot experiment and field experiment, so the actual control effect is still needed to validate with the field test.