溪黄草提取物对香蕉炭疽菌的抑制活性和抑菌机理

Antifungal Activity and Potential Mechanism of Isodon serra Extract Against Colletotrichum musae

摘要:

为开发防治香蕉炭疽病的天然抑菌剂，采用菌丝生长抑制和果实防治试验测定溪黄草(Isodon serra)提取物对香蕉炭疽菌(Colletotrichum musae)的抑制活性，通过研究提取物对菌丝细胞完整性、菌丝形态结构和能量代谢相关酶活性的影响探讨其抑菌机理。结果表明, 溪黄草醇提物及其不同极性溶剂萃取部位对香蕉炭疽菌均具有显著抑制活性，其中以石油醚萃取部位的抑菌活性最强，其对菌丝生长的半数抑制浓度为0.18 mg/mL。经不同浓度石油醚萃取部位处理的果实病斑直径均比空白对照显著下降(P<0.05)，浓度为4 mg/mL时，其与阳性对照无显著性差异(P>0.05)。石油醚萃取部位处理可破坏菌丝的细胞完整性，使细胞通透性提高，还可使菌丝发生显著质壁分离、皱缩和裂解，且破坏程度呈浓度依赖性。菌丝经2 mg/mL石油醚萃取部位处理后，琥珀酸脱氢酶、苹果酸脱氢酶、ATP合成酶、ATP酶活性分别下降23.56%、60.51%、9.01%和32.01%。溪黄草提取物通过破坏细胞完整性和降低能量代谢相关酶的活性来抑制香蕉炭疽菌正常生长，其对于防治香蕉炭疽病具有良好应用潜力。

Abstract:

In order to explore the natural antifungal agent of controlling banana anthracnose, antifungal activity of Isodon serra extract against Colletotrichum musae was evaluated by inhibition of mycelia growth and controlling activity test on banana fruits, and the potential mechanisms were investigated by studying the effect of I. serra extract on the mycelia cell integrity, mycelia morphology and activity of enzyme related to energy metabolism. The results showed that ethanol extract of I. serra and its different polar solvent extraction fractions had obvious antifungal activity against C. musae. Among them, petroleum ether fraction had the strongest inhibitory ability, its medium inhibitory concentration on mycelia growth was 0.18 mg/mL. The test of controlling activity on banana anthracnose showed that different concentrations of petroleum ether fraction decreased the lesion diameter of banana significantly compared with the control group (P<0.05), and the lesion diameter of banana treated with the extract at 4 mg/mL had no significant difference with the positive control (P>0.05). The integrity of C. musae mycelia cell was damaged significantly after incubation with the petroleum ether fraction, leading to the increase of cell permeability, moreover, the plasmolysis, shrinkage and crack in mycelia were also observed, and the damage degree was concentration-dependent. The enzyme activities of succinate dehydrogenase, malate dehydrogenase, ATP synthase and ATPase decreased by 23.56%, 60.51%, 9.01% and 32.01% respectively with the petroleum ether fraction treatment. In conclusion, these findings suggest that the antifungal mechanisms of I. serra extract against C. musae could be attributed to the disruption of cell structure and the effect on enzyme activities related to energy metabolism. Isodon serra extract could be used as a potential fungicide of controlling banana anthracnose.