Plant Molecular Biology

, Volume 84, Issue 4, pp 565–576

Early lignin pathway enzymes and routes to chlorogenic acid in switchgrass (Panicum virgatum L.)

  • Luis L. Escamilla-Treviño
  • Hui Shen
  • Timothy Hernandez
  • Yanbin Yin
  • Ying Xu
  • Richard A. Dixon
Article

DOI: 10.1007/s11103-013-0152-y

Cite this article as:
Escamilla-Treviño, L.L., Shen, H., Hernandez, T. et al. Plant Mol Biol (2014) 84: 565. doi:10.1007/s11103-013-0152-y

Abstract

Studying lignin biosynthesis in Panicum virgatum (switchgrass) has provided a basis for generating plants with reduced lignin content and increased saccharification efficiency. Chlorogenic acid (CGA, caffeoyl quinate) is the major soluble phenolic compound in switchgrass, and the lignin and CGA biosynthetic pathways potentially share intermediates and enzymes. The enzyme hydroxycinnamoyl-CoA: quinate hydroxycinnamoyltransferase (HQT) is responsible for CGA biosynthesis in tobacco, tomato and globe artichoke, but there are no close orthologs of HQT in switchgrass or in other monocotyledonous plants with complete genome sequences. We examined available transcriptomic databases for genes encoding enzymes potentially involved in CGA biosynthesis in switchgrass. The protein products of two hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase (HCT) genes (PvHCT1a and PvHCT2a), closely related to lignin pathway HCTs from other species, were characterized biochemically and exhibited the expected HCT activity, preferring shikimic acid as acyl acceptor. We also characterized two switchgrass coumaroyl shikimate 3′-hydroxylase (C3′H) enzymes (PvC3′H1 and PvC3′H2); both of these cytochrome P450s had the capacity to hydroxylate 4-coumaroyl shikimate or 4-coumaroyl quinate to generate caffeoyl shikimate or CGA. Another switchgrass hydroxycinnamoyl transferase, PvHCT-Like1, is phylogenetically distant from HCTs or HQTs, but exhibits HQT activity, preferring quinic acid as acyl acceptor, and could therefore function in CGA biosynthesis. The biochemical features of the recombinant enzymes, the presence of the corresponding activities in plant protein extracts, and the expression patterns of the corresponding genes, suggest preferred routes to CGA in switchgrass.

Keywords

Phenylpropanoid pathway Lignin Flavonoids Chlorogenic acid 

Supplementary material

11103_2013_152_MOESM1_ESM.docx (553 kb)
Supplementary material 1 (DOCX 552 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Luis L. Escamilla-Treviño
    • 1
    • 3
    • 4
  • Hui Shen
    • 1
    • 3
    • 4
  • Timothy Hernandez
    • 1
    • 3
  • Yanbin Yin
    • 2
    • 3
    • 5
  • Ying Xu
    • 2
    • 3
  • Richard A. Dixon
    • 1
    • 3
    • 4
  1. 1.Plant Biology DivisionSamuel Roberts Noble FoundationArdmoreUSA
  2. 2.Department of Biochemistry and Molecular BiologyUniversity of GeorgiaAthensUSA
  3. 3.Oak Ridge National LaboratoryBioEnergy Science Center (BESC)Oak RidgeUSA
  4. 4.Department of Biological SciencesUniversity of North TexasDentonUSA
  5. 5.Department of Biological SciencesNorthern Illinois UniversityDeKalbUSA

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