Relationship Between ATP Content and Desiccation-induced Injuries in Winter Rape Hypocotyls

Summary An inverse correlation between ATP content and membrane leakiness was observed inwinter rape hypocotyls subjected to moderate desiccation and showing incipient injuries (not higher than 20 % as checked by the conductivity method). The application of a phosphorylation inhibitor, DNP, mimicked the effect of water stress on membrane permeability and ATP content and decreased resistance of membranes to subsequent moderate dehydration. In hypocotyls exposed to the severe desiccation, showing a relatively high (ca. 50 %) membraneleakiness, no correlation between ATP and membrane permeability changes was noted. No effects of DNP on the parameters studied were observed. The results indicate that a desiccation stress has two types of effects on ATP content andmembrane modifications, the type being dependent on the severity of dehydration treatment; the decreased supply of ATP might be the primary reason for the initial membrane destabilization caused by moderate dehydration. On the other hand, pronounced losses of ATP in cells suffering from a high degree of membrane disorganization are probably due to accelerated ATP degradation in such decompartmentalized environments.