Ethylene and Benzaldehyde Emitted from Postharvest Tomatoes Inhibit via Binding to G-Protein Coupled Receptors and Transmitting with cAMP-Signal Pathway of the Fungus.

Tomato storage conditions are difficult largely due to infection which causes gray mold disease. However, the effects of the volatile organic compounds (VOCs) emitted by postharvest tomatoes on this fungus remain unclear. We analyzed the effects of tomato-emitted VOCs on pathogenicity, germination, and hyphal growth with bioassay, predicted the causative active compounds by principle component analysis, identified G-protein-coupled receptors (GPCRs) which captured chemical signals in the genome by stimulating molecular docking, tested the binding affinities of these receptors for the active compounds by fluorescence binding competition assay, and identified an associated signaling pathway by RNA interfere. The VOCs emitted by postharvest tomatoes inhibited ; ethylene and benzaldehyde were the active compounds causing this effect. One of the identified GPCRs in , BcGPR3, bound tightly to both active compounds. Two genes associated with the cAMP signaling pathway ( and ) were downregulated in wild-type exposed to the active compounds, as well as in the Δ mutant. Exposure to postharvest tomato VOCs reduces pathogenicity due to ethylene and benzaldehyde volatiles. The BcGPR3 protein is inactivated by the active compounds, and thus fails to transmit signals to the cAMP pathway, thereby inhibiting .