Alterations in carbon and nitrogen metabolism induced by water deficit in the stems and leaves of Lupinus albus L.

Water deficit (WD) in Lupinus albus L, brings about tissue-specific respons es that are dependent on stress intensity, Carbohydrate metabolism is very sensitive to changes in plant water status. Six days from withholding water (DAW), sucrose, glucose and fructose levels of the leaf blade had already increased over 5-fold, and the activities of SS and INVA had increased c, 1 .5-2 times. From 9 DAW on, when stress intensity was more pronounced, these effects were reversed with fructose and glucose concentrations as well as INVA activity dropping in parallel, The stem (specifically the stele) respo nded to the stress intensification with striking increases in the concentra tion of sugars, N and S, and in the induction of thaumatin-like-protein and an increase in chitinase and peroxidase. At 13 DAW, the plants lost most o f the leaves but on rewatering they fully recovered. Thus, the observed cha nges appear to contribute to a general mechanism of survival under drought, the stem playing a key role in that process.