CRISPR/Cas9 editing of p-COUMAROYL-CoA:MONOLIGNOL TRANSFERASE 1 in maize alters phenolic metabolism, lignin structure, and lignin-first biomass processing

Trends Biotechnol. 2025 May;43(5):1166-1195. doi: 10.1016/j.tibtech.2025.01.006. Epub 2025 Feb 15.

Abstract

Valorization of lignocellulosic biomass for sustainable production of high-value chemicals is challenged by the complexity of lignin, a phenolic biopolymer. Beyond the classical lignin monomers derived from p-coumaryl, coniferyl, and sinapyl alcohol, grass lignins incorporate substantial amounts of monolignol p-coumarates that are produced by p-COUMAROYL-CoA:MONOLIGNOL TRANSFERASE (PMT). Here, the CRISPR/Cas9-mediated mutation of ZmPMT1 in maize enabled the design of biomass depleted in p-coumaroylated lignin and enriched in guaiacyl lignin. Lignin-first biorefining of stem biomass from zmpmt1 mutants by reductive catalytic fractionation (RCF) generated a lignin oil depleted in carboxylates and enriched in guaiacyl-derived alcohols, which are desirable substrates for bio-based polyurethane synthesis. The reported lignin engineering in maize is a promising strategy for designing a dual-purpose crop, providing both food and feed, along with a renewable feedstock for the production of plant-based chemicals.

Keywords: BAHD acyltransferases; biomass saccharification; genome editing; grass lignocellulose; lignification; lignin hydrogenolysis; monolignol conjugates; p-coumarate; reductive catalytic fractionation (RCF).

MeSH terms

  • Biomass
  • CRISPR-Cas Systems* / genetics
  • Gene Editing* / methods
  • Lignin* / chemistry
  • Lignin* / metabolism
  • Phenols* / metabolism
  • Plant Proteins* / genetics
  • Plant Proteins* / metabolism
  • Plants, Genetically Modified
  • Zea mays* / enzymology
  • Zea mays* / genetics
  • Zea mays* / metabolism

Substances

  • Lignin
  • Phenols
  • Plant Proteins