Mechanistic profiling of Bifemetstrobin against the tea anthracnose pathogen and candidate evaluation of an amine oxidase target

Tea anthracnose caused by Glomerella cingulata threatens yield and quality, while resistance to legacy fungicides highlights the need for new modes of action. We characterized the antifungal activity and mechanism of bifemetstrobin against G. cingulata by combining efficacy assays with cell biology and integrated multi omics. Bifemetstrobin inhibited mycelial growth (EC50 = 5.04 μg/mL) and spore germination and provided up to approximately 80% curative suppression on detached tea leaves. Microscopy revealed dose dependent hyphal and conidial deformation and mitochondrial injury. Consistently, bifemetstrobin collapsed mitochondrial membrane potential (MMP), reduced intracellular ATP, and increased membrane leakage with depletion of reducing sugars and soluble proteins. Transcriptome, data-independent acquisition (DIA) proteomics and metabolome data converged on reprogramming of carbohydrate and amino acid metabolism, membrane processes, and redox homeostasis, with DNA replication signatures emerging at the higher dose. Cross-layer mapping prioritized an amine oxidase (AO) as a hub. Bifemetstrobin bound AO with micromolar affinity (microscale thermophoresis/isothermal titration calorimetry), supported by docking and molecular dynamics, and outperformed azoxystrobin in binding. Pairing bifemetstrobin with pyrrolnitrin yielded strong in vitro synergy and improved leaf protection. Across additional phytopathogens, bifemetstrobin retained activity in vitro (EC50 range 1.19–27.38 μg/mL), outperforming azoxystrobin on the tea anthracnose strain. These findings nominate AO as a high confidence candidate supported by binding assays and link target engagement to mitochondrial failure and carbon-nitrogen reprogramming, supporting bifemetstrobin (alone or in rational mixtures) as a promising candidate for tea anthracnose management.