Arabidopsis GELP53 overexpression modulates polysaccharide acetylation and defense through oligosaccharide-mediated signaling

Abstract O-acetylation is a crucial substitution found in hemicelluloses and pectin, which are necessary for maintaining the flexibility and structural integrity of the cell. Cell wall acetyl transferases and esterases maintain balanced polysaccharide O-acetylation levels, however the role of esterases in cell wall polysaccharide O-acetylation metabolism is not well explored. Therefore, we investigated the role of the Arabidopsis (Arabidopsis thaliana) GDSL Esterase/Lipase Protein (GELP) family member AtGELP53. Here, we show that AtGELP53 is localized in the plasma membrane. Analysis of AtGELP53-overexpressing independent transgenic lines revealed a decrease in xyloglucan acetylation, changes in acetylation of other polysaccharides, and alterations in cell wall composition. Molecular docking and in vitro protein activity assays showed that AtGELP53 might deacetylate xyloglucan and xylan. Elicitor-based, transcriptomic, and proteomic analyses in AtGELP53-overexpressing lines suggested that oligosaccharide-mediated signaling activates the cell wall and defense-related genes primarily through xyloglucan deacetylation. Furthermore, AtGELP53-overexpressing plants showed resistance against Pseudomonas syringae and Ralstonia solanacearum through activation of elicitor-mediated defense responses. Overall, our findings outline the role of AtGELP53 in polysaccharide acetylation, cell wall remodeling, and defense through oligosaccharide signaling.