In tobacco BY-2 cells xyloglucan oligosaccharides alter the expression of genes involved in cell wall metabolism, signalling, stress responses, cell division and transcriptional control.

Xyloglucan oligosaccharides (XGOs) arebreakdown products of XGs, the most abundant hemicellulosesof the primary cell walls of non-Poalean species.Treatment of cell cultures or whole plants with XGOsresults in accelerated cell elongation and cell division,changes in primary root growth, and a stimulation ofdefence responses. They may therefore act as signallingmolecules regulating plant growth and development. Previouswork suggests an interaction with auxins and effectson cell wall loosening, however their mode of action is notfully understood. The effect of an XGO extract fromtamarind (Tamarindus indica) on global gene expressionwas therefore investigated in tobacco BY-2 cells usingmicroarrays. Over 500 genes were differentially regulatedwith similar numbers and functional classes of genes upanddown-regulated, indicating a complex interaction withthe cellular machinery. Up-regulation of a putative XGendotransglycosylase/hydrolase-related (XTH) gene supportsthe mechanism of XGO action through cell wallloosening. Differential expression of defence-related genessupports a role for XGOs as elicitors. Changes in theexpression of genes related to mitotic control and differentiationalso support previous work showing that XGOsare mitotic inducers. XGOs also affected expression ofseveral receptor-like kinase genes and transcription factors.Hence, XGOs have significant effects on expression ofgenes related to cell wall metabolism, signalling, stressresponses, cell division and transcriptional control.