【目的】了解引起连作西瓜严重枯萎病的尖孢镰刀菌毒素对西瓜幼苗根和叶细胞有关生理功能的影响。【方法】用从尖孢镰刀菌西瓜专化型菌株提取的真菌毒素镰刀菌酸处理西瓜幼苗,考察其对细胞根系跨膜电位和叶片中相关抗逆酶的影响。【结果】高浓度镰刀菌酸处理西瓜幼苗12h后,根部细胞跨膜电位比对照下降61.9%～81.8%。不同浓度的毒素处理24h后,根系脱氢酶活性减少35.9%～90.9%。镰刀菌酸明显加速了叶片细胞膜脂质过氧化,24h后叶片丙二醛含量是对照的5.2～11.0倍。叶片中的苯丙氨酸解氨酶活性先增加,然后减少,6～12h活性最高,为对照的7.2～10.5倍。过氧化氢酶、超氧化物岐化酶、过氧化物酶也是先上升然后下降。过氧化氢酶活性在毒素处理3h后达到高峰,但再过3h后下降18.6%～52.5%。超氧化物岐化酶和过氧化物酶在毒素处理12h后达到最大,然后下降。叶片中的β-1,3-葡聚糖酶和几丁质酶在毒素处理后先快速上升,然后下降,最大活性分别出现在处理后12h和3h,分别是对照的10和15～30倍。【结论】镰刀菌酸强烈抑制了西瓜幼苗的根和叶细胞正常生理功能。破坏了叶片细胞的正常防卫系统和根细胞吸水和运输功能,引起细胞膜脂质过氧化生成大量的丙二醛,细胞结构遭受严重破坏,导致发病甚至细胞死亡。 【Objective】 The objective of this study was to investigate the effects of Fusarium oxysporum toxin on watermelon seedling root and leaf cell-related physiological functions. 【Method】 Watermelon seedlings were treated with mycotoxins Fusaric acid extracted from the Fusarium oxysporum watermelon strain and their effects on the transmembrane potential of the cell and the relevant anti-stress enzymes in the leaves were investigated. 【Result】 The results showed that the transmembrane potential of root cells decreased by 61.9% -81.8% compared with the control after being treated with high concentration of Fusaric acid for 12 h. After treated with different concentrations of toxin for 24 h, the activity of root dehydrogenase decreased by 35.9% -90.9%. Fusaric acid significantly accelerated the lipid peroxidation of leaf cell membrane, and the content of malondialdehyde in leaves after 24 hours was 5.2-11.0 times that of the control. Phenylalanine ammonia lyase activity in leaves first increased, then decreased, the highest activity of 6 ~ 12h, 7.2 to 10.5 times the control. Catalase, superoxide dismutase, peroxidase is also the first rise and then decline. Catalase activity peaked at 3 h after toxin treatment, but decreased by 18.6% -52.5% after 3 h. Superoxide dismutase and peroxidase reached the maximum after toxin treatment for 12 h, then decreased. Β-1, 3-glucanase and chitinase in leaves rapidly increased after toxin treatment and then decreased. The maximum activities appeared at 12 and 3 h after treatment, respectively 10 and 15 to 30 times of the control . 【Conclusion】 Fusaric acid strongly inhibited the normal physiological function of root and leaf cells of watermelon seedlings. Destroyed the normal defense system of leaf cells and the function of water absorption and transport of root cells, resulting in lipid peroxidation of the cell membrane to generate a large amount of malondialdehyde. The cell structure was severely damaged, leading to morbidity and even cell death.