Influence of xyloglucan oligosaccharides on the micromorphology of the walls of suspension-cultured Rubus fruticosus cells

The deposition of xyloglucans in the incipient wall of Rubus fruticosus cells grown in suspension was examined by transmission electron microscopy. The general distribution of polysaccharides and the formation of a middle lamella was followed along the cell growth period with cytochemical reagents. A predominant morphological change of the cell walls, which are in direct contact with the culture medium, is the reorientation of the superficial cellulose microfibrils which form a loose layer oriented towards the medium. Changes of xyloglucan localization during growth were observed via a polyclonal antibody. When the cells age the loosened superficial microfibrils are progressively depleted in the associated xyloglucans. This phenomenon was accelerated when the nonasaccharide XG9 (XXFG) was added to the culture medium. This is the first observation of an effect of oligosaccharides on the morphology of the plant cell wall at the ultrastructural level.