Speakers - 2026

Title: A host-derived isoflavonoid induces oomycete apoptosis-like death in phytophthora capsici and enhances host protection

Abstract

Phytopathogenic oomycetes pose a major threat to crop production, yet the endogenous plant metabolites that directly regulate oomycete survival remain poorly understood. Here, we identify the isoflavonoid daidzin as an infection-associated metabolite linked to host resistance and show that it suppresses Phytophthora capsici by disrupting pathogen development and triggering oomycete apoptosis-like death (OALD). Comparative metabolomic analyses of resistant and susceptible hosts revealed a positive association between daidzin accumulation and disease resistance. Exogenous daidzin inhibited vegetative growth, reduced zoosporogenesis, and triggered OALD in P. capsici. Drug-affinity-responsive target stability, coupled with label-free proteomics, identified six candidate daidzin-binding proteins, including the centrosomal spindle body protein PcCEP44 and the carbohydrate-binding protein PcCBM9_1A. Disruption of PcCEP44 and PcCBM9_1A partially phenocopied daidzin treatment, causing developmental defects and accelerated OALD. Liposomal and chitosan-based nanoformulations further enhanced daidzin uptake, anti-oomycete activity, and disease suppression in planta. Daidzin also promoted root growth and was associated with increased indole-3-acetic acid accumulation, suggesting a link between defense-associated metabolism and growth regulation. Together, these findings identify daidzin as a host-derived metabolite with direct anti-oomycete activity and provide a mechanistically informative framework for understanding metabolite-induced pathogen cell death.

Keywords: Oomycete apoptosis-like death (OALD); Metacaspases; Target-based chemical genomics; Nano-enabled crop protection; Phytophthora capsici.