A 5-enolpyruvylshikimate 3-phosphate synthase functions as a transcriptional repressor in populus

Meng Xie, Wellington Muchero, Anthony C. Bryan, Kelsey Yee, Hao Bo Guo, Jin Zhang, Timothy J. Tschaplinski, Vasanth R. Singan, Erika Lindquist, Raja S. Payyavula, Jaime Barros-Rios, Richard Dixon, Nancy Engle, Robert W. Sykes, Mark Davis, Sara S. Jawdy, Lee E. Gunter, Olivia Thompson, Stephen P. Difazio, Luke M. EvansKim Winkeler, Cassandra Collins, Jeremy Schmutz, Hong Guo, Udaya Kalluri, Miguel Rodriguez, Kai Feng, Jin Gui Chen, Gerald A. Tuskan

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Long-lived perennial plants, with distinctive habits of inter-annual growth, defense, and physiology, are of great economic and ecological importance. However, some biological mechanisms resulting from genome duplication and functional divergence of genes in these systems remain poorly studied. Here, we discovered an association between a poplar (Populus trichocarpa) 5-enolpyruvylshikimate 3-phosphate synthase gene (PtrEPSP) and lignin biosynthesis. Functional characterization of PtrEPSP revealed that this isoform possesses a helix-turn-helix motif in the N terminus and can function as a transcriptional repressor that regulates expression of genes in the phenylpropanoid pathway in addition to performing its canonical biosynthesis function in the shikimate pathway. We demonstrated that this isoform can localize in the nucleus and specifically binds to the promoter and represses the expression of a SLEEPER-like transcriptional regulator, which itself specifically binds to the promoter and represses the expression of PtrMYB021 (known as MYB46 in Arabidopsis thaliana), a master regulator of the phenylpropanoid pathway and lignin biosynthesis. Analyses of overexpression and RNAi lines targeting PtrEPSP confirmed the predicted changes in PtrMYB021 expression patterns. These results demonstrate that PtrEPSP in its regulatory form and PtrhAT form a transcriptional hierarchy regulating phenylpropanoid pathway and lignin biosynthesis in Populus.

Original languageEnglish
Pages (from-to)1645-1660
Number of pages16
JournalPlant Cell
Volume30
Issue number7
DOIs
StatePublished - Jul 2018

Funding

This research was funded by The BioEnergy Science Center and The Center for Bioenergy Innovation from 2007 to 2017 and from 2017 to 2018, respectively. Both are U.S. Department of Energy Research Centers (Grant DE-AC05-00OR22725) supported by the Office of Biological and Environmental Research in the DOE Office of Science. Oak Ridge National Laboratory is managed by UT-Battelle for the U.S. Department of Energy.

FundersFunder number
BioEnergy Science Center
U.S. Department of EnergyDE-AC05-00OR22725

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