4-Biphenylboronic Acid Exerts Antifungal Activity against Neopestalotiopsis ellipsospora via Dual Targeting of Plasma Membrane Integrity and Cell Wall Biogenesis

Abstract Neopestalotiopsis ellipsospora causes tea leaf spots, reducing yield and processed tea quality and resulting in economic losses. This study investigated the antifungal activity and mechanism of 4-biphenylboronic acid using mycelial growth inhibition assays, enzymatic analyses, electron microscopy, and RNA sequencing. The compound showed strong antifungal activity against N. ellipsospora with an EC50 of 10.72 mg/L. Mechanistic analyses indicated that 4-biphenylboronic acid disrupted plasma membrane integrity, impaired membrane bioenergetics and solute transport, and perturbed cell wall homeostasis. Transcriptome profiling further identified downregulation of genes associated with chitin biosynthesis, including plasma membrane H+-ATPase, alkaline ceramidase, G-protein-coupled receptor, and chitin synthase 1. Together, these findings suggest that 4-biphenylboronic acid inhibits N. ellipsospora through the coordinated disruption of mitochondrial energy metabolism, membrane function, and cell wall biogenesis.