The <scp>MYC2</scp>‐<scp>JAMYB</scp> transcriptional cascade regulates rice resistance to brown planthoppers

Abstract

Plant defense against herbivores is primarily regulated by the phytohormone jasmonate (JA). At the core, JA signaling is the MYC2 transcription factor (TF) that regulates the expression of an extensive array of defense-related genes. However, the regulatory mechanisms underlying MYC2-mediated herbivore resistance in rice are not fully understood. We employed brown planthopper (BPH) bioassays, transcriptional activation assays, transcriptome profiling, targeted metabolomics and cleavage under targets and tagmentation-sequencing analysis to investigate the biological function and regulatory mechanism of the JAMYB TF. JAMYB is induced by BPH infestation and is transcriptionally regulated by MYC2. Mutations of JAMYB rendered rice plants susceptible to BPH attacks under laboratory and field conditions, indicating that JAMYB positively contributes to BPH resistance. BPH-elicited biosynthesis of phenolamides and volatile compounds was reduced in jamyb mutants compared with wild-type plants. These specialized metabolites, regulated by JAMYB, function as direct and indirect defenses to deter BPH damage or attract parasitoid wasps of BPH eggs. Furthermore, we found that JAMYB directly binds to AC motifs of key phenylpropanoid pathway genes and activates their expression, likely altering the metabolic flux for phenolamide biosynthesis. This study reveals the role of the MYC2-JAMYB module in JA-mediated rice resistance to BPH.