The pharmaceutically valuable monoterpene indole alkaloids (MIAs) in Catharanthus roseus are derived from the indole and iridoid pathways that respond to jasmonate (JA) signaling. Two classes of JA-responsive bHLH transcription factor (TF), CrMYC2 and BIS1/BIS2, are known to regulate the indole and iridoid pathways, respectively. However, upregulation of either one of the TF genes does not lead to increased MIA accumulation. Moreover, little is known about the interconnection between the CrMYC2 and BIS transcriptional cascades and the hierarchical position of BIS1/BIS2 in JA signaling. Here, we report that a newly identified bHLH factor, Repressor of MYC2 Targets 1 (RMT1), is activated by CrMYC2 and BIS1, and acts as a repressor of the CrMYC2 targets. In addition, we isolated and functionally characterized the core C. roseus JA signaling components, including CORONATINE INSENSITIVE 1 (COI1) and JASMONATE ZIM domain (JAZ) proteins. CrMYC2 and BIS1 are repressed by the JAZ proteins in the absence of JA, but de-repressed by the SCFCOI 1 complex on perception of JA. Our findings suggest that the repressors, JAZs and RMT1, mediate crosstalk between the CrMYC2 and BIS regulatory cascades to balance the metabolic flux in MIA biosynthesis.
|Number of pages||16|
|State||Published - Mar 2018|
Bibliographical noteFunding Information:
We thank John May (Department of Civil Engineering and Environmental Research Training Laboratories, University of Kentucky) for assistance in LC-MS/MS analysis. This work was supported in part by the Harold R. Burton Endowed Professorship to L.Y. and by the National Science Foundation under Cooperative Agreement no. 1355438 to L.Y.
© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust
- Catharanthus roseus
- jasmonate (JA)
- terpenoid indole alkaloids
- transcriptional regulation
ASJC Scopus subject areas
- Plant Science