Hispidulin impairs cyst germination and pathogenicity of Phytophthora sojae through Hint1-dependent signaling
Phytophthora sojae, a destructive oomycete pathogen, causes severe root rot in soybeans. Although flavonoids are known antifungal agents, their effects on oomycetes remain unclear. Here, we systematically evaluated representative flavonoids against P. sojae, revealing that the flavone hispidulin significantly inhibits cyst germination (EC50 = 13.29 uM) and, at higher concentrations, also suppresses mycelial growth and oospore production. Hispidulin-treated soybean seedlings displayed markedly reduced disease symptoms, indicating its strong suppression in pathogenicity. Transcriptome analysis following hispidulin treatment uncovered candidate genes involved in the response, among which Hint1, a gene linked to cyst germination and virulence, was identified and functionally validated as a key mediator. These findings renew insights into the molecular basis of flavonoid-driven oomycete inhibition and highlight the potential of flavonoid-based strategies for controlling soybean root rot.