Grass lignin: biosynthesis, biological roles, and industrial applications

Abstract

Lignin is a phenolic heteropolymer found in most terrestrial plants that contributes an essential role in plant growth, abiotic stress tolerance, and biotic stress resistance. Recent research in grass lignin biosynthesis has found differences compared to dicots such as Arabidopsis thaliana. For example, the prolific incorporation of hydroxycinnamic acids into grass secondary cell walls improve the structural integrity of vascular and structural elements via covalent crosslinking. Conversely, fundamental monolignol chemistry conserves the mechanisms of monolignol translocation and polymerization across the plant phylum. Emerging evidence suggests grass lignin compositions contribute to abiotic stress tolerance, and periods of biotic stress often alter cereal lignin compositions to hinder pathogenesis. This same recalcitrance also inhibits industrial valorization of plant biomass, making lignin alterations and reductions a prolific field of research. This review presents an update of grass lignin biosynthesis, translocation, and polymerization, highlights how lignified grass cell walls contribute to plant development and stress responses, and briefly addresses genetic engineering strategies that may benefit industrial applications.

Dendrometry, production and nutritional value of Mimosa caesalpiniifolia Benth. under monocrop and silvopastoral system

“…Lignin synthesis requires high energy and nutrient uptake, which can be limited during drought stress (Peracchi et al 2024). Furthermore, this fraction is richer in carbon and less hydrated when compared to hemicellulose and cellulose fractions, which can increase the demand for water for the synthesis of this compound (Rupitak and Srisaikam, 2021).…”

Unlocking the Potential of Catechyl Lignin: Molecular Regulation of Biosynthesis, Structural Organization, And Valorization

“…The global population growth has increased the demand for chemicals and fuels, exacerbating challenges like the energy crisis and environmental. − Sustainable development is crucial, focusing on efficient biorefineries that convert nonedible biomass, particularly lignocellulose, into eco-friendly products. , Lignocellulose comprises cellulose (40–45%), hemicellulose (30–35%), and lignin (15–30%), making it a promising feedstock for biofuels and biochemicals (Figure A and C). − Lignin, a complex biopolymer in plant cell walls, influences structural support and defense mechanism, formed from three monolignols, namely coniferyl alcohol (G unit), sinapyl alcohol (S unit), and p-coumaryl alcohol (H unit) (Figure B). Its structure includes diverse linkages such as β-O-4 , β–β , and β-5 structures (Figure C), , impacting its properties and applications. Natural lignins vary widely (termed ’G/S-lignin’), complicating broad use, thus bioengineering modifies lignin composition, such as by enhancing sinapyl alcohol production, to improve efficiency and material performance in biorefineries (Figure C) .…”