Evaluating the Potential Value of Natural Product Cuminic Acid against Plant Pathogenic Fungi in Cucumber

Fusarium wilt and anthracnose are two major diseases which limit the yield and quality of cucumber worldwide. Cuminic acid was extracted from the seed ofCuminum cyminumL. The mean EC50values of cuminic acid for inhibiting mycelial growth and zoospore germination of fiveFusarium oxysporumf. sp.cucumerinumstrains were 25.66 ± 3.02 μg/mL and 15.99 ± 2.19 μg/mL, and of fourColletotrichum lagenarium(Pass.) Ellis and Halsted strains were 29.53 ± 3.18 μg/mL and 18.41 ± 2.78 μg/mL, respectively. In greenhouse experiments, cuminic acid at 2000 μg/mL exhibited 70.77% protective and 62.63% curative efficacies againstF. oxysporum, and 65.43% protective and 55.46% curative efficacies againstC. lagenarium. Moreover, the translocation behavior of cuminic acid, determined by high performance liquid chromatography (HPLC), showed that it could be readily absorbed and transported upward and downward in cucumber. Importantly, superoxide dismutase (SOD) and pyphenol oxidase (PPO) activities of cucumber leaves treated with cuminic acid increased significantly. All results indicated that cuminic acid showed antifungal activity, and could be used as a botanical fungicide in disease management. This study encourages further investigation on the mechanism of action of cuminic acid and the development of alternative antifungal drugs.Keywords:botanical fungicide;cuminic acid;cucumber;F. oxysporum;C. lagenarium;control efficacy