黄蜻幼虫肠道真菌QTYC-51的鉴定及其除草活性成分

Identification and phytotoxic activity of fungus QTYC-51 from the gut of Pantala flavescens larvae

摘要:

[目的] 鉴定黄蜻幼虫肠道中具有除草活性的真菌，并分析其除草活性成分。[方法] 通过形态学观察和分子生物学5.8S rDNA-ITS序列分析，明确菌株QTYC-51的分类地位。结合培养皿生物分析法测定菌株发酵液和单体化合物的除草活性，采用色谱方法从该菌乙酸乙酯粗提物中分离活性成分，并利用质谱和核磁共振谱鉴定活性物质。[结果] 菌株QTYC-51被鉴定为拟盾壳霉属菌（Paraconiothyrium sp.），其发酵液对稗草和反枝苋幼根生长有较好的抑制作用，抑制率分别为76.9%和56.5%。从QTYC-51发酵产物中分离到5个单体化合物，分别为1，8-dihydroxyanthraquinone，1-hydroxy-10-methoxy-dibenz[b，e]oxepin-6，11-dione，hydroxyvertixanthone，globosuxanthone和1，3，6，8-tetrahydroxyanthraquinone。在供试浓度为100 μg/mL时，化合物globosuxanthone对稗草和反枝苋幼根生长有明显的抑制作用，抑制率分别为94.1%和79.0%，与阳性对照2，4-二氯苯氧乙酸效果相当；化合物1-hydroxy-10-methoxy-dibenz[b，e]oxepin-6，11-dione具有较好的除草活性，对稗草和反枝苋幼根的生长抑制率分别为50.3%和58.6%。[结论] 菌株QTYC-51具有开发为微生物源除草剂的潜能。

Abstract:

[Objective] To isolate the fungus with phytotoxic activity from the gut of Pantala flavescens larvae. [Methods] Strain QTYC-51 was identified by morphological observation and 5.8S rDNA-ITS sequence analysis. Petri dish bioassay was used to test the phytotoxic activity of fermentation broth and monomer compounds of strain QTYC-51 on Echinochloa crusgalli and Amaranthus retroflexus. Bioactive components were isolated from ethyl acetate extracts via chromatographic methods, and the structures were determined by mass spectrum and nuclear magnetic resonance analyses.[Results] QTYC-51 was identified as Paraconiothyrium sp.. The fermentation broth had good phytotoxic activity on radical growth of E. crusgalli and A. retroflexus with the inhibition rates of 76.9% and 56.5%, respectively. Five monomer compounds were purified from the fermentation products, including 1,8-dihydroxyanthraquinone, 1-hydroxy-10-methoxy-dibenz[b,e]oxepin-6,11-dione, hydroxyvertixanthone, globosuxanthone and 1,3,6,8-tetrahydroxyanthraquinone. At the concentration of 100 μg/mL, compound globosuxanthone was found to possess obvious phytotoxic effects on radical growth of E. crusgalli and A. retroflexus with the inhibition rates of 94.1% and 79.0%, respectively, which were comparable to that of positive control 2,4-dichlorophenoxyacetic acid. Compound 1-hydroxy-10-methoxy-dibenz[b,e] oxepin-6,11-dione showed potent phytotoxic activity against E. crusgalli and A. retroflexus with inhibition rates of 50.3% and 58.6%, respectively.[Conclusion] Strain QTYC-51 could be potentially developed as a microbial herbicide.