A 5-Enolpyruvylshikimate 3-Phosphate Synthase Functions as a Transcriptional Repressor in Populus

Mark Davis, Meng Xie, Wellington Muchero, Anthony Bryan, Kelsey Yee, Hoa-Bo Guo, Jin Zhang, Timothy Tschaplinski, Vasanth Singan, Erika Lindquist, Raja Payyavula, Jaime Barros-Rios, Richard Dixon, Sara Jawdy, Lee Gunter, Olivia Thompson, Stephen DiFazio, Luke Evans, Kim Winkeler, Cassandra CollinsJeremy Schmutz, Hong Guo, Udaya Kalluri, Miguel Rodriguez, Kai Feng, Jin-Gui Chen, Gerald Tuskan, Nancy Engle, Robert Sykes

Research output: Contribution to journalArticlepeer-review

54 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 languageAmerican English
Pages (from-to)1645-1660
Number of pages16
JournalPlant Cell
Volume30
Issue number7
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 ASPB.

NREL Publication Number

  • NREL/JA-2700-71648

Keywords

  • lignin biosynthesis
  • poplar
  • populus
  • transcriptional repressors

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