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 fruit and vegetable crops, apigenin's 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 , P. 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.