Aerenchyma in sugarcane roots: a toolbox for tailoring biomass for bioenergy

Sugarcane is a major feedstock for first-generation (1G) ethanol production, but the efficient conversion of its lignocellulosic residues into second-generation (2G) biofuels remains limited by the resilience of its cell wall. Here, we suggest sugarcane root aerenchyma as a relevant biological model to study in vivo mechanisms of cell wall breakdown. By performing spatial transcriptomic profiling across four root segments representing different stages of aerenchyma development, we identified over 32,000 differentially expressed transcripts (DETs), including many genes that encode cell wall-modifying proteins. Co-expression network analysis and functional annotation revealed stage-specific expression of glycoside hydrolases, glycosyltransferases, and expansins, aligning with the gradual degradation of wall components. Among these, an α-L-arabinofuranosidase (ScASD1) was chosen for biotechnological validation due to its strong transcriptional induction. Heterologous expression in Pichia pastoris and saccharification assays with sugarcane bagasse showed that ScASD1 significantly improves reducing sugar release when used with a commercial enzyme cocktail. Our results support using sugarcane aerenchyma as a platform to discover plant-derived enzymes, and establish ScASD1 as a promising candidate for enhancing hydrolytic efficiency in 2G ethanol production. This approach aligns with sustainable bioenergy goals and offers a scalable method to lower costs and promote circularity in sugarcane-based biorefineries.