Abscisic acid modifies the changes in lipids brought about by water stress in the moss Atrichum androgynum

Mosses are particularly able to withstand drought stress. Moreover, abscisic acid (ABA), which is intimately involved during stress in higher plants, has also been implicated in bryophytes. Because membrane damage is a common feature of drought stress, we have studied changes in lipid composition during desiccation and rehydration of the moss Atrichum androgynum and the effect of exogenous ABA on these processes. In order to correlate any membrane changes with drought stress, we analysed different lipid classes by thin-layer chromatography, fatty acid composition by gas-liquid chromatography and lipid peroxidation. Water stress caused changes in phosphoglyceride composition consistent with an activation of phospholipase D and of phosphatidylinositol metabolism. Recovery of phosphoglyceride composition towards original levels occurred during rehydration and ABA treatment reduced the overall extent of changes. Reduction in thylakoid lipids and chlorophyll coincided with loss of photosynthesis. The data show that mosses respond to drought stress similarly to higher plants and that ABA may reduce membrane damage by diminishing the lipid changes.