The role of lipid metabolism in the acquisition of desiccation tolerance in Craterostigma plantagineum: a comparative approach

Abstract

SUMMARYDehydration leads to different physiological and biochemical responses in plants. We analysed the lipid composition and the expression of genes involved in lipid biosynthesis in the desiccation-tolerant plant Craterostigma plantagineum. A comparative approach was carried out with Lindernia brevidens (desiccation tolerant) and two desiccation-sensitive species, Lindernia subracemosa and Arabidopsis thaliana. In C. plantagineum the total lipid content remained constant while the lipid composition underwent major changes during desiccation. The most prominent change was the removal of monogalactosyldiacylglycerol (MGDG) from the thylakoids. Analysis of molecular species composition revealed that around 50% of 36:x (number of carbons in the acyl chains: number of double bonds) MGDG was hydrolysed and diacylglycerol (DAG) used for phospholipid synthesis, while another MGDG fraction was converted into digalactosyldiacylglycerol via the DGD1/DGD2 pathway and subsequently into oligogalactolipids by SFR2. 36:x-DAG was also employed for the synthesis of triacylglycerol. Phosphatidic acid (PA) increased in C. plantagineum, L. brevidens, and L. subracemosa, in agreement with a role of PA as an intermediate of lipid turnover and of phospholipase D in signalling during desiccation. 34:x-DAG, presumably derived from de novo assembly, was converted into phosphatidylinositol (PI) in C. plantagineum and L. brevidens, but not in desiccationsensitive plants, suggesting that PI is involved in acquisition of desiccation tolerance. The accumulation of oligogalactolipids and PI in the chloroplast and extraplastidial membranes, respectively, increases the concentration of hydroxyl groups and enhances the ratio of bilayer-to non-bilayer-forming lipids, thus contributing to protein and membrane stabilization.

Understanding the Biochemical Basis of Temperature-Induced Lipid Pathway Adjustments in Plants

“…In wheat, we also detected decreased C34 DGDG and increased C36 DGDG at low temperature. A boosted channeling of C34 DAG moieties from the ER to chloroplast for DGDG biosynthesis has previously been observed under phosphate-deprived condition (Härtel et al, 2000), while an export of C36 DAG moieties from chloroplast for phospholipid biosynthesis in the ER was noted during dehydration in plants (Gasulla et al, 2013). Thus, differential channeling of C34 DAG and C36 DAG moieties between the ER and chloroplast could be an important mechanism of plant adaptation to environmental stress.…”

Synthesis and transfer of galactolipids in the chloroplast envelope membranes of Arabidopsis thaliana

“…Fatty acid methyl esters were transmethylated and quantified by GC using pentadecanoic acid (15:0) as an internal standard (43). Galactolipids and phospholipids were quantified by direct infusion mass spectrometry (44).…”

Structural Determinants Allowing Transferase Activity in SENSITIVE TO FREEZING 2, Classified as a Family I Glycosyl Hydrolase

“…Less is known about the action of SFR2 on lyso-MGDG in vivo, partly because of its low abundance (67). Because GH1 family enzymes are frequently specific for the sugar group, and less frequently for the leaving group, lyso-MGDG is an attractive possible alternative substrate.…”