脱氢乙酸钠抑制指状青霉的作用机制

Antifungal Mechanism of Sodium Dehydroacetate against Penicillium digitatum

脱氢乙酸钠(sodium dehydroacetate,SD)可有效抑制指状青霉(Penicillium digitatum)的生长,但其作用机制尚不清楚。本实验通过分析不同质量浓度SD(0(对照)、1/2最小抑菌质量浓度(minimum inhibitory concentration,MIC)、MIC)对P.digitatum菌丝体细胞结构和功能(细胞壁、细胞膜和线粒体)的影响,研究SD的抑菌机制。结果表明,SD处理菌丝体30 min时已通过主动运输进入细胞内,且在整个处理期间能维持胞内较高的SD质量浓度;SD处理的菌丝体细胞壁荧光强度和胞外碱性磷酸酶(alkaline phosphatase,AKP)活力与对照无明显差异;而碘化丙啶染色实验结果表明,SD引起菌丝体荧光强度显著增加(P<0.05);此外,SD处理能够降低菌丝体总脂质含量,并提升胞外pH值,表明SD处理对菌丝体细胞膜造成损伤而未对细胞壁造成损伤。此外,SD处理降低了菌丝体线粒体膜电位和能荷水平,增加了Na^(+)/K^(+)-ATPase活力,干扰了细胞能量代谢。SD对金柑果实绿霉病干预实验结果表明,SD处理有效抑制了金柑果实绿霉病的发生,且呈质量浓度依赖效应。综上,SD可通过破坏P.digitatum菌丝体细胞膜和线粒体的结构和功能发挥其抑菌活性,从而降低金柑采后绿霉病的发生。研究结果可为SD应用于金柑采后病害绿色防控提供理论依据。

Studies have found that sodium dehydroacetate (SD) can effectively inhibit the growth of Penicillium digitatum but its inhibitory mechanism remains unclear. In this study, the antifungal mechanism of SD was analyzed by measuring the effects of different concentrations of SD on the cell structure and function (cell wall, cell membrane and mitochondria) of P. digitatum mycelia. Results showed that SD entered the cells by active transport after 30 min of treatment and intracellular SD concentration was maintained at a high level during the treatment period. Compared with the untreated control group,the fluorescence intensity of cell wall and the extracellular alkaline phosphatase (AKP) activity of SD-treated mycelial cells were not significantly different, whereas propidium iodide staining showed that SD caused a significant increase in the fluorescence intensity of mycelia (P < 0.05), decreased the total lipid content of mycelia, and increased the extracellular pH,indicating that SD treatment directly damaged the cell membrane without damaging the cell wall. SD treatment also reduced the mycelial mitochondrial membrane potential and energy charge levels and increased Na^(+)/K^(+)-ATPase activity, thereby disturbing cellular energy metabolism. Intervention experiments showed that SD treatment effectively inhibited the incidence of green mold of inoculated kumquat fruit in a concentration-dependent manner. The above results indicated that SD exerts its antifungal effect and reduces the incidence of green mold in postharvest kumquat fruit by damaging the structure and function of the cell membrane and mitochondria of P. digitatum mycelia. These findings can provide a theoretical basis for the application of SD in the green control of postharvest kumquat diseases.