Accumulation of polyethylene glycol 6000 and its effects on water content and carbohydrate level in water-stressed tomato plants

Abstract

Young tomato [Lycopersicon escudentum] plants were grown in 10 or 25% polyethylene glycol (PEG) 6000 solutions to impose water stress. Plant organs were analyzed to ascertain whether the various plant parts accumulated PEG and to determine the physiological effects. PEG 6000 was taken up by tomato roots and translocated to the shoots. PEG accumulations was greater in roots and in the first leaves and negligible in apical leaves. In all leaves there was an increase in soluble-sugar concentration during the PEG treatment. However, PEG-accumulating leaves showed a delay in dehydration in comparison with leaves where PEG was not accumulated. To explain this behaviour we hypothesize that PEG was accumulated in extracellular spaces and that, as a consequence, water was drawn out from the cells, inducing cellular but not tissue dehydration.