Antifungal Activity and Action Mode of Cuminic acid

Watermelon fusarium wilt caused by Fusarium oxysporum f.sp. niveum (FON) is a 13 destructive soil-borne disease throughout the world leading to serious economic losses and limit 14 watermelon production. Cuminic acid, extracted from the seed of Cuminum cyminum L., belongs to 15 benzoic acid analogues. In this study, the median effective concentration (EC50) values for cuminic 16 acid in inhibiting mycelial growth of FON was 22.53μg/mL. After treatment with cuminic acid, 17 mycelial morphology was seriously influenced; cell membrane permeability and glycerol content 18 were increased markedly, but pigment and mycotoxin (mainly fusaric acid) were significantly 19 decreased. Synthesis genes of bikaverin and fusaric acid both were down regulated compared with 20 the control confirmed by quantitative RT-PCR. In greenhouse experiments, cuminic acid at all 21 concentrations displayed significant bioactivities against FON. Importantly, significant 22 enhancement of activities of SOD, POD, CAT and decrease of MDA content after cuminic acid 23 treatment in watermelon leaves were observed in vivo. These indicated that cuminic acid not only 24 showed high antifungal activity, but also could enhance the self-defense system of the host plant. 25 Above all, cuminic acid showed the potential as a biofungicide to control FON. 26