Identification of Critical Mutation in a Novel Regulator of Lignin Synthesis in Poplar

The Science

Identify functional SNPs in Populus trichocarpa PtrEPSP-TF responsible for a novel transcriptional repressor regulating phenylpropanoid (PP) biosynthesis.

  • Used GWAS studies to predict high-impact SNPs in PtrEPSP-TF.
  • Characterized transgenic lines heterogeneously expressing PtrEPSP-TF and performed phenotypic and transcriptomic analyses to discover downstream regulators in the PP pathway.

The Impact

  • Defined SNPs at the 142nd amino acid of PtrEPSP-TF as the primary determinator of function.
  • Uncovered 5 new TF negatively regulating PP biosynthesis.
  • Provides molecular targets for precision genome-editing to regulate PP biosynthesis to improve biomass feedstocks characteristics.


In plants, the phenylpropanoid pathway is responsible for the synthesis of a diverse array of secondary metabolites that include lignin monomers, flavonoids, and coumarins, many of which are essential for plant structure, biomass recalcitrance, stress defense, and nutritional quality. Previous studies have demonstrated that Populus trichocarpa PtrEPSP-TF, an isoform of 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase, has transcriptional activity and regulates phenylpropanoid biosynthesis in Populus. This study identifies the key amino acid required for PtrEPSP-TF functionality and provides a strategy to uncover new transcriptional regulators in phenylpropanoid biosynthesis.


Xie, M., J. Zhang, V. R. Singan, M. J. McGranahan, P. R. LaFayette, S. S. Jawdy, N. Engle, C. L. Doeppke, T. J. Tschaplinski, E. Lindquist, K. Barry, J. Schmutz, W. A. Parrott, F. Chen, G. A. Tuskan, J.-G. Chen, W. Muchero, and M. Davis. 2020. “Identification of Functional Single Nucleotide Polymorphism of Populus trichocarpa PtrEPSP-TF and Determination of its Transcriptional Effect,” Plant Direct 4(1), 1–13. DOI:10.1002/pld3.178.