The longevity of biologically-active oligogalacturonides in rose cell cultures: degradation by exo-polygalacturonase

To study the metabolism of oligosaccharins, we monitored the fate of (6- 14 C)-labelled oligo-α-(1→4)-D-galacturonides of degree of polymerization 8 and 9 (GalA 8 and GalA 9 ) when administered at ∼1 μM to cell suspension cultures of 'Paul's Scarlet' rose (Rosa sp.). Neither GalA 8 nor GalA 9 was appreciably taken up by or bound to the cells. Both GalA 8 and GalA 9 were rapidly hydrolysed by the culture (half-life 2-4 h). The products were smaller oligogalacturonides and galacturonic acid, indicating the action of exo-polygalacturonase. It is suggested that exo-polygalacturonase plays an important role in controlling the concentrations of biologically-active oligogalacturonides in uninfected plant tissues.