The solubility of primary plant cell wall polysaccharides in LiCl-DMSO

In order to understand the architecture of the primary plant cell wall, knowledge on its polysaccharides and their interactions is of importance. In this study, further architectural insight was obtained by sequential LiCl-DMSO and buffer extractions after planetary ball milling. After milling, up to 50% of all polysaccharides in the Chelating agent Unextractable Solids (ChUS) from carrot, tomato and strawberry solubilised in LiCl-DMSO without loss of structural information. Approximately 30% of all pectin was LiCl-DMSO insoluble but solubilised in the subsequent buffer extraction, and these populations had higher HG:RG-I ratios than LiCl-DMSO soluble populations. The degree of methyl-esterification (DM) of pure pectins highly determined its solubility in LiCl-DMSO. However, solubility of cell wall pectin was governed by more factors since both soluble and insoluble pectin were substantially methyl-esterified and acetylated. Digestion of LiCl-DMSO soluble and insoluble fractions by pectinases confirmed the presence of acetylated HG-regions for carrot and strawberry pectin.