A MYC2, MYC3, MYC4-dependent transcription factor network regulates touch responses in plants

Plants are continuously exposed to environmental triggers, including mechanical stimulation. Our results demonstrate that jasmonic acid (JA)-signalling plays a key role in very early gene expression changes, well before it leads to touch-induced developmental changes. We show that the JA-activated transcription factors MYC2/MYC3/MYC4 co-regulate touch-induced gene expression of 266 genes, many of which peak in induction around 25 minutes and then rapidly decline by 40-60 minutes. ChIP-seq shows that MYC2 dynamically binds hundreds of touch-induced promoters within 25 minutes. Promoter activation assays confirm that MYC2 directly activates these touch-induced promoters. By combining multi-omic data, we have identified a core MYC2/3/4-dependent ‘touch regulon’, containing many previously-unknown MYC2 targets like bHLH19 and ERF109. We show bHLH19 can in turn directly activate the ORA47 promoter, indicating that MYC2/3/4 initiate a hierarchical network of downstream transcription factors. Through hormone profiling we reveal the rapid touch-induced accumulation of JA/JA-isoleucine is directly controlled by MYC2/3/4 in a positive amplification loop regulating JA-biosynthesis genes.