余甘子采后软腐病拮抗菌的筛选、鉴定及其防效

Identification and biocontrol effect of antagonistic Streptomyces against postharvest Penicillium fruit rot of Phyllanthus emblica L.

摘要:

【背景】由青霉菌引起的软腐病是余甘子采后贮藏期的主要病害，造成了经济损失严重。【目的】筛选对余甘子软腐病菌具有良好拮抗效果的放线菌菌株，并初步评价拮抗菌无菌发酵液的防治效果。【方法】以Penicillium choerospondiatis DQ23为指示菌，采用琼脂块法结合生长速率法进行拮抗菌株的筛选，并采用形态学特征、生理生化特性结合16S rRNA基因序列进行分类鉴定，并采用浸果法初步测定其无菌发酵液对余甘子软腐病发生及果实贮藏品质的影响。【结果】菌株SC-15对青霉P. choerospondiatis DQ23有较强的拮抗作用，拮抗圈直径为18.70 mm，20%无菌发酵液对软腐病菌的抑制率可达87.8%。根据菌株形态学和生理生化特性，结合16S rRNA基因序列分析将菌株SC-15鉴定为维及尼链霉菌Streptomyces virginae。菌株SC-15无菌发酵液能降低余甘子的腐烂率和腐烂指数，延缓可溶性固形物和可滴定酸的降低，其中75%发酵液浸果效果最好，贮藏8 d后，果实腐烂率为53.3%，果实腐烂指数为35.2%，可溶性固形物为4.8%，可滴定酸为6.25 mg/g。【结论】菌株SC-15可有效防治余甘子采后青霉软腐病的发生，具有一定的应用价值。

Abstract:

[Background] Fruit rot caused by Penicillium choerospondiatis is the main postharvest disease of Phyllanthus emblica L., and frequently causes serious fruit decay and large economic loss. [Objective] To obtain and evaluate the control effects of actinomycetes strains with strong antagonistic effect on P. emblica rot fungi. [Methods] Agar disk method and growth rate method were used to screen antagonistic strains against P. choerospondiatis DQ23, and the morphological, physiological and biochemical characteristics combined with 16S rRNA gene sequence were used for classification and identification. The biocontrol effect of the cell-free fermentation broth on fruit rot and quality of P. emblica was evaluated. [Results] Strain SC-15 had a strong antagonistic effect on P. choerospondiatis DQ23 mycelial growth with inhibition zone diameter of 18.70 mm. The inhibition rate of cell-free fermentation broth on mycelial growth of P. choerospondiatis DQ23 reached 87.8%. Based on the morphological and physiological characteristics and 16S rRNA gene sequence analysis, strain SC-15 was identified as Streptomyces virginae. The disease percentage and disease severity index of P. emblica fruit decreased significantly after the treatment via soaking in cell-free fermentation broth of strain SC-15 before storage. The decrease rate of soluble solids and titratable acids in the treated fruits was also slowed down. The results showed that 75% of cell-free fermentation broth had the best protection against P. emblica fruit rot. On the 8th day of storage, the fruit disease percentage was 53.3%, the fruit disease severity index was 35.2%, the content of soluble solids and titratable acid were 4.8% and 6.25 mg/g, respectively. [Conclusion] Streptomyces virginae SC-15 can effectively prevent postharvest fruit rot of Phyllanthus emblica caused by P. choerospondiatis.