INFLUENCE OF XYLOGLUCAN OLIGOSACCHARIDES ON SOME ENZYMES INVOLVED IN THE HYPERSENSITIVE REACTION TO TNV (TOBACCO NECROSIS VIRUS) OF CUCUMBER COTYLEDONS

The changes in activity of the enzymes peroxidase, beta-1,3-glucanase and chitinase in the extracellular fluid of cucumber cotyledons after treating with xyloglucan fragments prepared from tamarind seeds and pe a stems in connection with the hypersensitive reaction of cucumber to TNV (tobacco necrosis virus) has been studied. Chitinase activity incr eased in response to treating with xyloglucan fragments at a concentra tion 0.5 mg/ml, whereas that of peroxidase and beta-1,3-glucanase rema ined unchanged. The activity of these two enzymes increased more rapid ly 24 h after inoculation of TNV on treated cotyledons. At a later sta ge, when the local lesions became visible, the activities of these enz ymes were lower than those of the untreated controls. Stimulation of r elease and accumulation of these enzymes in the extracellular fluid of oligosaccharide-treated cucumber cotyledons demonstrated the biologic al activity of xyloglucan oligosaccharides also in relation to the hyp ersensitive reaction to TNV. The changes in the activity of these enzy mes are probably connected with decreased lesion numbers developed on treated cucumber cotyledons.