Plants adapt and survive adverse environmental changes by altering their membrane lipid composition. Sesuvium portulacastrum L., a facultative halophyte has been extensively studied for its adaptability to various abiotic stresses. However, knowledge on the identification of glycerolipids and changes in their profile in coping up with the stressors is limited. In this investigation, electrospray ionization tandem mass spectrometry (ESI?MS/MS) was used for identifying glycerolipid molecular species in the halophyte and to study changes in their profile during pre- and post monsoon seasons. The study showed when environmental conditions changed from post to premonsoon season, the lipidome switched from galactoglycerolipids, such as monogalactosyl diacylglycerol (MGDG, GL1), lyso-digalactosyl diacylglycerol (lyso-DGDG,GL2) and digalactosyl monoacylglycerol phosphatidic acid (DGMAPA, GL3) to MGDGs (GL1;GL1a), monogalactophosphatidyl glycerols (MGPGs, GL4-GL7) and sulfonoglycolipids, (SQMG, GL8) and (SQDGs, GL9 and GL10). Glycolipids GL1-2, GL8 and GL10 are reported earlier while glycerophospholipids (GL3-GL7) are new natural products. The degree of fatty acid unsaturation of polar lipid fraction decreased with stronger abiotic stresses. Polyhydroxy nature of glycerolipids played a protective role against oxidative damage during harsh condition by acting as oxygen radical scavengers. Saturation of the fatty acyl chain contributed to the homeostasis of membrane fluidity and permeability.
Keywords: Aizoaceae, ESI-MS, Glycerolipids, Halophyte, Structure