八角炭疽病拮抗放线菌RX2-2的分离鉴定及其生物活性评价

Isolation,identification,and bioactivity evaluation of an actinomycetes strain RX2-2 against star anise anthracnose

摘要:

【背景】八角炭疽病主要是由哈锐炭疽菌(Colletotrichum horii)引起的真菌性病害，给八角产业带来严重的经济损失。【目的】从八角根系土壤中分离筛选对哈锐炭疽菌具有拮抗作用的放线菌菌株，并对其进行种属鉴定及抗菌活性评价。【方法】采用稀释涂布平板法分离放线菌，并以哈锐炭疽菌作为指示菌，利用平板对峙法筛选具有高拮抗活性的菌株；基于形态特征、培养特性、生理生化特性和16S rRNA基因序列分析对该菌株进行种属鉴定；采用对峙生长法及菌 丝生长速率法对该菌株的拮抗活性进行评价，并采用离体叶片法测定其无菌发酵液的室内防效。【结果】筛选得到一株对哈锐炭疽菌具有较强拮抗活性的菌株RX2-2，其皿内抑制活性达95.48%，该菌对其他7种植物病原真菌和5种常见细菌均具有较好的拮抗作用，抗菌谱较广。发酵液中的抗菌活性物质具有良好的热稳定性。无菌发酵液对感染哈锐炭疽菌的离体八角叶片防控效果高达47.62%。根据该菌的形态特征、生理生化特征及16S rRNA基因序列分析，初步鉴定菌株RX2-2为Streptomyces lunalinharesii。【结论】菌株RX2-2对八角炭疽病有较好的防治效果，具有潜在的应用价值。

Abstract:

[Background] Star anise anthracnose is a fungal disease caused by Colletotrichum horii,which has caused serious economic losses to star anise industry in China. [Objective]To isolate and screen out the actinomycetes strains with inhibitory effect on C. horii from the rhizosphere soil of star anise trees.[Methods]Actinomycetes strains were isolated by dilution-plating method,and a plate confrontation experiment was conducted to screen out the strains with antagonistic effects on C. horii.The antagonistic strain was identified based on morphological,physiological,and biochemical characteristics combined with 16S rRNA gene sequence analysis.The antagonistic activity was evaluated based on the mycelial growth rate.The biocontrol effect of the cell-free fermentation broth was tested with detached star anise leaves.[Results]An actinomycetes strain RX2-2 was isolated from the rhizosphere soil of star anise trees,which had a strong antagonistic effect against C. horii, with the inhibition rate of 95.48%.RX2-2 had a broad antimicrobial spectrum,with strong inhibitory effects on other seven plant pathogenic fungal species and five common bacterial species.The antibacterial substances in the fermentation broth of RX2-2 have good thermal stability.The cell-free fermentation broth showed the biocontrol effect up to 47.62% on detached star anise leaves infected with C. horii.RX2-2 was identified as Streptomyces lunalinharesii based on the morphological,physiological,and biochemical characteristics in combination with 16S rRNA gene sequence.[Conclusion]RX2-2 has a promising prospect in the biological control of star anise anthracnose and other plant diseases.