Jasmonate and salicylate signaling in rice defense against brown planthopper nymphs

BACKGROUND: The brown planthopper (BPH), Nilaparvata lugens (Stål), is a notorious piercing-sucking herbivore in paddy fields. While jasmonate (JA) signaling is known to mediate rice defense against BPH female adults, the phytohormonal mechanisms underlying resistance to nymphs, which inflict damage solely through feeding, without oviposition, remain unclear. RESULTS: In this study, we demonstrate that BPH nymph infestation elicits the accumulation of both JA and salicylic acid (SA) in rice leaf sheaths, accompanied by significant upregulation of JA- and SA-responsive genes. Overexpression of the JA core transcription factor MYC2 in a susceptible rice cultivar enhanced resistance to nymphs, whereas JA-deficient lines exhibited susceptibility comparable to wild-type plants. In contrast, SA-deficient NahG overexpression plants did not alter nymph resistance, and an NPR1 (SA receptor) mutation unexpectedly increased resistance. Compared to female adult feeding, nymph infestation induced milder upregulation of JA-responsive genes and defensive specialized metabolites. CONCLUSION: Our findings indicate that JA, but not SA signaling, contributes to rice defense against BPH nymphs. © 2025 Society of Chemical Industry.