A Newly Identified Gene Controls Lignin Acetylation in Poplar

Acetylation in plant cell walls, including lignin, plays a critical role in biomass processability. High acetate content facilitates uncatalyzed, additive-free hot-water or steam hydrolysis, releasing acetic acid without the need for mineral acids or other chemical pretreatments. Despite the prevalence of acetylation in certain plant species, the genes and enzymes responsible for lignin and xylem acetylation remain largely uncharacterized. Here, we report the identification and functional characterization of an acetyl-CoA:monolignol transferase gene in Populus. Overexpression of this gene in transgenic poplars led to elevated acetate levels in lignin without negatively impacting plant growth or development. Acetate accumulation was positively correlated with gene expression, and among 18 independent transgenic lines, several showed at least a sevenfold increase compared to wild-type controls. This work establishes a genetic basis for lignin acetylation and provides a promising strategy to engineer biomass with improved pretreatability, enhancing the efficiency of biofuel and bioproduct production.