Interface Alterations in Cellulose Synthases Redefine CESA Complex Assembly to Enhance Cellulosic Biomass Production

Cellulose, a major component of plant cell walls and a critical bioeconomy resource, is synthesized by cellulose synthase complexes (CSCs). Understanding the assembly and function of CSCs, driven by cellulose synthase (CESA) proteins, is essential for enhancing biomass and tailoring cellulose properties for various applications. This study integrates evolutionary analysis, structural modeling, and functional data to elucidate the sequence-structure–function relationships of CESAs. We analyzed key interface residues within plant-conserved regions, transmembrane helices, and zinc-finger domains, revealing functional specialization through variations among duplicated CESAs, subfamilies, and plant groups. Our findings indicate that CESA gene duplication and interface residue divergence, coupled with tissue-specific and environment-dependent expression and post-translational modifications, drive CSC diversification. These alterations in CESAs may redefine CSC assembly. Heterologous expression of an evolutionarily distant CESA, such as Sorghum bicolor secondary wall CESA8 in Arabidopsis, may favor the formation of exogenous homomeric CSCs, leading to increased cellulose synthesis and enhanced plant growth. This increase in cellulose synthesis is associated with pectin demethylation, a process known to promote plant cell expansion. Based on these findings and previous studies, we propose a working model for enhanced biomass production. In this model, interface alterations in CESAs redefine CSC assembly, allowing overexpressed CESAs to form homomeric complexes that enhance cellulosic biomass production.