Determination of changes in membrane lipid composition during rehydration and dehydration of the resurrection plant Xerophyta humilis using multiple reaction monitoring mass spectrometry

摘要

Plants whose fully differentiated tissues are able to withstand desiccation to air-dryness for prolonged periods of time and able to resume their full metabolic functioning in existing tissues upon rewatering are termed resurrection plants. Considerable research has been conducted on the structural, physiological, biochemical and molecular changes accompanying dehydration and recovery of a number of resurrection plants in order to ascertain the protective processes that enable survival of extreme water loss. However, to date there has been little published on the roles of lipids in desiccation tolerance. Lipids are a key component of membranes and maintenance of membrane integrity during abiotic stresses, such as water deficit, is likely to play an important role in survival. It has been shown that during the freeze-associated desiccation events, the nature and changes in lipid composition enable appropriate membrane re-arrangements, facilitating survival of this stress. In the current study LC-MS/MS in the MRM mode is being used to profile and quantify levels of membrane lipids in roots and leaves of the resurrection plant Xerophyta humilis during dehydration and rehydration cycles. For comparison purposes, lipid profiles and changes in the desiccation sensitive model organism, Arabidopsis thaliana is being followed. Preliminary results obtained thus far indicate considerable differences in lipid composition between Xerophyta humilis and A. thaliana tissues. During dehydration of vegetative tissues of the resurrection plant, changes in four distinct classes of glycerophospholipids have been noted. The nature of these changes, and potential implication thereof, will be discussed.