Lignin biosynthesis and its integration into metabolism

• Published in: Current opinion in biotechnology Vol. 56; no. C; pp. 230 - 239
• Main Authors: Vanholme, Ruben, De Meester, Barbara, Ralph, John, Boerjan, Wout
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2019; Elsevier
• Subjects: BASIC BIOLOGICAL SCIENCES; biochemical pathways; biosynthesis; Biosynthetic Pathways; Cell Wall - metabolism; cell walls; lignin; Lignin - biosynthesis; Lignin - chemistry; Lignin - metabolism; Metabolome; pathogens; physicochemical properties; Plant Development; polymerization; Propanols - metabolism; sinapyl alcohol
• ISSN: 0958-1669; 1879-0429; 1879-0429
• DOI: 10.1016/j.copbio.2019.02.018

[Display omitted] •To date, metabolites from more than 10 different metabolic classes have been identified as lignin building blocks, totaling 35 monomers.•Despite this flexibility, limitations appear to exist for the extent that lignin composition can be altered.•The flux through the lignin biosynthetic pathway is regulated at multiple levels.•Upon pathway perturbations, pathway intermediates accumulate and are converted into a wide range of derivatives.•Pathway intermediates and derivatives are either incorporated into the lignin polymer, or remain soluble, potentially affecting physiological processes. Lignin is a principal structural component of cell walls in higher terrestrial plants. It reinforces the cell walls, facilitates water transport, and acts as a physical barrier to pathogens. Lignin is typically described as being composed of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units that derive from the polymerization of the hydroxycinnamyl alcohols, p-coumaryl, coniferyl, and sinapyl alcohol, respectively. However, lignin also derives from various other aromatic monomers. Here, we review the biosynthetic pathway to the lignin monomers, and how flux through the pathway is regulated. Upon perturbation of the phenylpropanoid pathway, pathway intermediates may successfully incorporate into the lignin polymer, thereby affecting its physicochemical properties, or may remain soluble as such or as derivatized molecules that might interfere with physiological processes.