Disruption of olfactory perception in the Empoasca onukii Matsuda by a defensive green leaf volatile, (Z)-3-hexenal

The tea green leafhopper (TLH, Empoasca onukii Matsuda) poses a major economic threat to the tea industry, and current practice on using synthetic insecticides raises ecological and health concerns. Green leaf volatiles (GLVs), a group of plant-derived volatile organic compounds, play vital roles in plant defense against herbivores. However, the specific GLVs mediating tea plant resistance to E. onukii and the molecular mechanisms underlying the insect's perception of these cues remain unclear. This study aimed to identify key defense-related GLVs in tea plants and elucidate the chemosensory mechanisms governing E. onukii's behavioral responses for explaining chemical communication and advancing sustainable pest control strategies.

Mechanical-wounding induced a large release of (Z)-3-hexenal (Z3Hal) as a major defense-related GLV in the resistant cultivar (LJ43) that elicits strong antennal responses (-26 mV) and repels E. onukii. The gene EnouCSP14 was selected from RNA-Seq data and silenced via RNAi in vivo, which significantly reduced antennal responses to Z3Hal. In vitro fluorescence competitive binding assays (FCBA) showed moderate binding affinity (28.7 μM) of EnouCSP14 protein to Z3Hal. Molecular docking further predicted that Z3Hal interacted with amino acid residues Ile123 and Phe96 of EnouCSP14.

Our findings demonstrate that Z3Hal is a key GLV that repels E. onukii, and that EnouCSP14 mediates its detection. This study advanced understanding of the chemical ecology underlying tea plant-herbivore interactions and highlights EnouCSP14 protein as a promising molecular target for developing RNAi-based strategies to regulate the olfactory system of E. onukii. © 2026 Society of Chemical Industry.