NlGSTs3 Facilitates Adaptation of Nilaparvata lugens to Rice by Metabolizing Ferulic Acid and Resorcinol

Abstract Insect herbivores rely on glutathione S-transferases (GST) to cope with host-derived secondary metabolites, yet the specific role of individual GST isoforms in mediating host adaptation remains poorly understood. Here, we characterized the sigma-class GST gene NlGSTs3 and its role in host plant adaptation of the brown planthopper Nilaparvata lugens. NlGSTs3 was predominantly expressed in the fat body and testes. RNAi-mediated knockdown of NlGSTs3 significantly reduced survival and feeding performance on rice plants and specifically increased susceptibility to ferulic acid and resorcinol. Molecular docking predicted favorable interactions between NlGSTs3 and these two compounds, which was further supported by in vitro catalytic assays showing recombinant NlGSTs3 mediates the depletion of ferulic acid and resorcinol. This work demonstrates that NlGSTs3 contributes to the adaptation of N. lugens to rice chemical defenses through the substrate-specific metabolism of ferulic acid and resorcinol, suggesting that NlGSTs3 may be a promising target for RNAi-mediated BPH management.