Competitive binding of pectin and xyloglucan with primary cell wall cellulose

Assemblies of pectin, xyloglucan and cellulose were studied in vitro using two ternary systems. In the first one, xyloglucan concentration varied, while pectin amount was kept constant. In the second one, pectin concentration varied, whereas xyloglucan amount was fixed. The use of ternary systems allowed to put forward the hypothesis that pectin/cellulose and xyloglucan/cellulose associations may exist together or separately, depending on the proportion of non-cellulosic polysaccharides in cell walls. It can be hypothesized that pectin plays a double role within primary cell walls: (i) pectin loosely bound to cellulose, in xyloglucan-rich cell walls, (ii) pectin associated with cellulose, in xyloglucan-poor cell walls.