Targeting the V-ATPase A Subunit in Phytophthora sojae: Discovery of Compound A15.

Phytophthora sojae poses a major threat to global soybean production. Here, CRISPR/Cas9-mediated promoter replacement revealed that the V-ATPase A subunit gene (PsVHA-A) plays an important role in the growth, development, and pathogenicity of P. sojae, highlighting its potential as a molecular target. Using this target, a multistage docking-based virtual screening identified compound A15 as a potent antioomycete inhibitor, with EC50 values of 4.082-8.974 μg/mL against six oomycetes. A15 markedly inhibited mycelial growth and key developmental stages in P. sojae in vitro and protected soybean leaves from infection in vivo without affecting soybean seed germination or seedling growth. Mechanistically, A15 potentially interacted with PsVHA-A, inhibited V-ATPase activity, and disrupted vacuolar homeostasis, cell wall structure, and energy metabolism. Collectively, our findings establish VHA-A as a promising oomycete-specific fungicidal target and identify A15 as a valuable lead compound for the development of selective antioomycete agents.