香茅精油对番茄早疫病菌的抑菌作用及抑菌机制

为探明香茅精油的抑菌作用及其在植物病害生物防治中的应用价值,采用平板抑菌法和熏蒸法测定了香茅精油对番茄早疫病菌的抑菌活性,及其对菌丝体内电解质渗漏、可溶性蛋白质含量、丙二醛(MDA)含量、营养物质的吸收和超氧化物歧化酶(SOD)活性的影响.结果表明: 香茅精油对番茄早疫病菌有较强的抑菌作用,且该作用具有时间-剂量依赖性,但无杀菌作用.采用熏蒸法处理的抑制效果较平板抑菌法更好,处理48 h后,半抑制浓度(IC₅₀)分别为13.40 μL·L^-1和103.23 mg·L^-1;处理144 h后,IC₅₀分别为33.81 μL·L^-1和145.16 mg·L^-1.125 mg·L^-1香茅精油处理12 h后,菌丝体的电导率和MDA含量分别为对照的2.7和2.2倍,SOD活性和可溶性蛋白质含量分别提高88.5%和21.9%,还原糖的吸收减少11.3%.香茅精油可通过破坏病原菌细胞膜完整性和抑制菌体对营养物质的吸收来抑制病原菌菌丝的生长.香茅精油在植物病害生物防治中有一定的开发潜力.

The antimicrobial activity and mechanism of Cymbopogon citratus essential oil against Alternaria solani.

To explore the antifungal function and application potential of Cymbopogon citratus essential oil in the biological control of plant diseases, the disk-diffusion and fumigation methods were used to measure the inhibitory effect of C. citratus essential oil against Alternaria solani and its effect on cell membrane permeability, soluble protein and malondialdehyde (MDA) content, nutrient absorption, and superoxide dismutase (SOD) activity of mycelium. The results showed that C. citratus essential oil had a strong time and dose-dependent inhibitory effect, however showed no sterilization effect on A. solani. Overall, fumigation was a more effective method than disk-diffusion. After 48 hours of C. citratus essential oil treatment, the half maximal inhibitory concentration (IC₅₀) values were 13.40 μL·L^-1 and 103.23 mg·L^-1 for fumigation and disk-diffusion, respectively. After 144 hours, they were 33.81 μL·L^-1 and 145.16 mg·L^-1, respectively. The conductivity and MDA content of mycelium were 2.7 and 2.2 folds as that of the control 12 hours after C. citratus essential oil treatment of 125 mg·L^-1, the SOD activity and soluble protein content were increased by 88.5% and 21.9%, and the absorption of reducing sugar was decreased by 11.3%. These results indicated that C. citratus essential oil could inhibit the growth of A. solani mycelium by destroying cell membrane integrity and reducing nutrient absorption, which should be taken as a potential biological agent for controlling plant diseases.