Apigenin and Apigenin-7-O-β-d-Glucoside Enhance Pepper Defense Against Phytophthora capsici by Inhibiting Pathogen Growth and Reproduction

Apigenin is a natural plant flavonoid known for its remarkable biological activity. While numerous studies have documented the accumulation of glycosylated and non-glycosylated apigenin in fruits and vegetable crops, their direct and indirect effects on plant resistance remain poorly understood. This study employed non-targeted metabolomics strategies to monitor metabolome-reprogramming events in susceptible, moderately resistant, and highly resistant pepper (Capsicum annuum) cultivars challenged with Phytophthora capsici. Results revealed a positive correlation between the accumulation of apigenin and apigenin-7-O-β-d-glucoside in pepper seedlings inoculated with P. capsici and the resistance characteristics of the individual pepper cultivars. Further, we demonstrated that both apigenin and apigenin-7-O-β-d-glucoside significantly inhibited the vegetative growth of economically important phytopathogenic oomycetes and fungi, including P. capsici, Phytophthora sojae, Pyricularia oryzae, Fusarium graminearum, and Colletotrichum siamense. These findings highlight the potential applications of glycosylated and non-glycosylated apigenin in developing biopesticides to support the environment-friendly prevention and control of critical crop fungal and oomycete diseases.