Résumé
Plant cell walls are made of interacting networks of polysaccharides (cellulose, hemicelluloses, pectins) and some structural proteins. Cellulose-xyloglucan networks are considered to be the main source of structural strength in primary cell wall. Little is known about the contribution of each polysaccharide network to mechanical properties. The aim of this work is to evaluate the role of hemicellulose, especially xyloglucans, by monitoring plant cell wall mechanical properties during targeted enzymatic degradation and establishing links with xyloglucan chemical composition and structure.Spatially homogeneous parenchyma from contrasted texture Golden Delicious (Go) and Granny Smith (Gr) apples were sampled and vacuum infused with enzymes in buffer solution aimed at maintaining and homogenising turgor pressure and limiting oxidation. Glucanases specific from xyloglucan and/or cellulose backbone and glycoside hydrolases (α-fucosidase, and β-galactosidase) were used to study the impact of xyloglucan and its side chains on parenchyma mechanical properties by dynamic mechanical analysis. The results emphasize the key roles of side chains in the regulation of mechanical properties and are interpreted as resulting from direct modifications of polysaccharides conformations and interactions or indirect regulation of endogenous enzymes involved in the remodelling of networks assemblies. This study explores how xyloglucan can be related to the mechanical function emerging at the tissue scale and provides insight into structure-function relationships during plant organ development.