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

作者：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^*

来源：Plant Cell, 2018, 30(7): 1645-1660.

DOI：10.1105/tpc.18.00168

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.

• 出版日期2018-7