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

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

doi:10.1105/tpc.18.00168

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

Journal Article · Mon Jun 11 00:00:00 EDT 2018 · The Plant Cell

DOI:https://doi.org/10.1105/tpc.18.00168· OSTI ID:1441118

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BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996
U.S. Department of Energy Joint Genome Institute, Walnut Creek, California 94598
BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, Texas 76203
Bioscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401
Department of Biology, West Virginia University, Morgantown, West Virginia 26506
ArborGen, Ridgeville, South Carolina 29472
U.S. Department of Energy Joint Genome Institute, Walnut Creek, California 94598, HudsonAlpha Institute for Biotechnology, Huntsville, Alabama 35806
BioEnergy Science Center and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, U.S. Department of Energy Joint Genome Institute, Walnut Creek, California 94598

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.

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Research Organization:: National Renewable Energy Laboratory (NREL), Golden, CO (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)