Which is thought to suppress formation of the non-lamellar membrane phase increases in fatty acid desaturation, which enhances membrane fluidity and thus favors dehydration resistance ; increases in PA, which is proposed to be an early signal of cellular dehydration and a structural feature of membrane injury. Many metabolic enzymes regulate the lipid ASP1517 changes induced by cellular dehydration. Phospholipases hydrolyze phospholipids at different positions to produce lyso-phospholipids, diacylglycerol, or PA. Phospholipases might be the most important enzymes in resurrection plants because they contribute to many aspects of dehydration-induced changes in membrane lipids. For example, the increases in the levels of PA and DAG that occur as levels of other phospholipids decrease during dehydration in Craterostigma plantagineum suggest that phopholipases C and D act in response to dehydration. Dramatic increases in the abundances of lyso-phospholipids caused by freezing-induced cellular dehydration suggest roles for phospholipase A and/or B in responses to dehydration. In particular, the role of phospholipase D-mediated PA formation has been extensively studied in processes related to cellular dehydration. However, recent reports indicate that rather than increasing, levels of PA might even decline following desiccation in A. thaliana. These findings suggest that there are still unknown responses of lipid changes to dehydration. These include rocky outcrops and arid zones within tropical and subtropical areas. In general, these plants are small. Among the approximately 300 angiosperm resurrection species, more than two dozen belong to the family Gesneriaceae. To further examine which lipids were degraded, we compared acyl structures among the molecular species during rehydration to monitor potential turnover reactions. We found that all degraded molecular species corresponded to the increases of PA molecular species with the same acyl structures, except for the individual PS molecular species that were present at very low levels. For example, the decrease of 34:6 MGDG specifically corresponded to the increase of 34:6 PA; this suggests that 34:6 MGDG was converted to 34:6 PA. This is consistent with our previously described observations following freezinginduced dehydration of A. thaliana. Interestingly, however, the acyl structures of increased DAG molecular species did not correspond to those of any other decreased lipid molecular species. This suggests that DAG was not directly derived from the major membrane lipids. These results indicate that membrane lipids of A. thaliana are degraded dramatically during both desiccation and rewatering, but that their degradation patterns varied and that most degradation occurred during rewatering. The results also suggest that the membrane lipids were degraded directly through PA and indirectly through DAG. The mechanisms responsible for the remarkable responses of resurrection plants to desiccation, particularly their changes of membrane lipids, have been reported extensively.