|MYC2 Orchestrates a Hierarchical Transcriptional Cascade that Regulates Jasmonate-Mediated Plant Immunity in Tomato
Minmin Du, Jiuhai Zhao, David T. W. Tzeng, Yuanyuan Liu, Lei Deng, Tianxia Yang, Qingzhe Zhai, Fangming Wu, Zhuo Huang, Ming Zhou, Qiaomei Wang, Qian Chen, Silin Zhong, Chang-Bao Li, and Chuanyou Li
The Plant Cell
The hormone jasmonate (JA), which functions in plant immunity, regulates resistance to pathogen infection and insect attack through triggering genome-wide transcriptional reprogramming in plants. We show that the basic helix-loop-helix transcription factor (TF) MYC2 in tomato (Solanum lycopersicum) acts downstream of the JA receptor to orchestrate JA-mediated activation of both the wounding and pathogen responses. Using chromatin immunoprecipitation sequencing (ChIP-seq) coupled with RNA sequencing (RNA-seq) assays, we identified 655 MYC2-targeted JA-responsive genes. These genes are highly enriched in Gene Ontology categories related to TFs and the early response to JA, indicating that MYC2 functions at a high hierarchical level to regulate JA-mediated gene transcription. We also identified a group of MYC2-targeted TFs (MTFs) that may directly regulate the JA-induced transcription of late defense genes. Our findings suggest that MYC2 and its downstream MTFs form a hierarchical transcriptional cascade during JA-mediated plant immunity that initiates and amplifies transcriptional output. As proof of concept, we showed that during plant resistance to the necrotrophic pathogen Botrytis cinerea, MYC2 and the MTF JA2-Like (JA2L) form a transcription module that preferentially regulates wounding-responsive genes, whereas MYC2 and the MTF ETHYLENE RESPONSE FACTOR.C3 (ERF.C3) form a transcription module that preferentially regulates pathogen-responsive genes.