Effects of xylooligosaccharides on suspension-cultured cells and protoplasts of Pinus radiata

The effects of xylooligosaccharides isolated from the cell walls of Betula platyphylla var. japonica on cells and protoplasts of Pinus radiata were examined. The addition of a semi-purified mixture of xylooligosaccharides at a concentration of 5 mu g.ml(-1) promoted elongation of cultured cells, whereas the neutral fraction of this mixture had no effect; a similar effect was seen in the presence of conditioned medium. The unfractionated mixture of xylooligosaccharides was also found to enhance the viability of protoplasts prepared from cell cultures of Pinus radiata in a concentration dependent manner, highly similar to the effect provided by addition of medium conditioned by pine cells. Such effects are considered to be due to the addition of components that play a structural role in the cell wall of pines. It is inferred that the acidic components of the xylooligosaccharides mixture derived from Betula are responsible for this effect in the distant pine species. It is speculated that acidic xylooligosaccharide operate either by replacing, or mimicking, the natural cell wall components required for growth and development of pine cultured cells.