Membrane phospholipids as a phosphate reserve: the dynamic nature of phospholipid‐to‐digalactosyl diacylglycerol exchange in higher plants

Abstract

It is well established that phosphate deficiency induces the replacement of membrane phospholipid with nonphosphorous lipids in extra-plastidial membranes (e.g. plasma membrane, tonoplast, mitochondria). The predominant replacement lipid is digalactosyl diacylglycerol (DGDG). This paper reports that the phospholipid-to-DGDG replacement is reversible, and that when oat seedlings are re-supplied with radio-labelled phosphate, it is initially recovered primarily in phosphatidylcholine (PC). Within 2 d, the shoot contains more than half of the lipidassociated radiolabel, reflecting phosphate translocation. Oat was also cultivated in different concentrations of phosphate and the DGDG/PC ratio in roots and phospholipase activities in isolated plasma membranes was assayed after different times of cultivation. The DGDG/PC ratio in root tissue correlated more closely with plasma membranelocalized phospholipase D, yielding phosphatidic acid (PA), than with plasma membrane-localized PA phosphatase, the activity that results in a decreased proportion of phospolipids. The lipid degradation data did not reflect a significant involvement of phospholipase C, although a putative phospholipase C analogue, non-specific phospholipase C4 (NPC4), was present in oat roots. The correlation between increased phospholipase D activity and DGDG/PC ratio is consistent with a model where phospholipid-to-DGDG replacement involves formation of PA that readily is removed from the plasma membrane for further degradation elsewhere.

Phosphate Deprivation in Maize: Genetics and Genomics

“…Although this array did not represent the full genome, it showed the change in expression of lipid-related genes, particularly an increase in transcript levels for genes involved in sulfolipid synthesis. In contrast to Arabidopsis, where phospholipid degradation is mediated by transcriptional regulation of phospholipases C and D (Misson et al, 2005;Tjellströ m et al, 2008), maize roots under P stress did not present a modification in the expression of these genes. Instead, a strong induction of phospholipase A2 and glycerophosphodiesterases, also related to phospholipid degradation, was reported, suggesting triacylglycerol breakdown (Calderon-Vazquez et al, 2008).…”

Membrane Glycerolipid Remodeling Triggered by Nitrogen and Phosphorus Starvation inPhaeodactylum tricornutum

“…No intense trafficking is required for this replacement, as SQDG and PG are both chloroplast lipids. The most spectacular feature of Arabidopsis lipid remodeling consists in the replacement of PC in a variety of subcellular locations, such as the plasma membrane, the tonoplast, and the mitochondria (but not observed in the endoplasmic reticulum [ER]), by DGDG synthesized in the chloroplast, using still uncharacterized lipid export systems (Andersson et al, 2003(Andersson et al, , 2005Jouhet et al, 2003Jouhet et al, , 2004Jouhet et al, , 2007Jouhet et al, , 2010Sandelius et al, 2007;Tjellström et al, 2008).…”

Regulatory Hotspots Are Associated with Plant Gene Expression under Varying Soil Phosphorus Supply in Brassica rapa

“…These included two transcripts with homology to glycerophosphoryl diester phosphodiesterases and a transcript with homology to Arabidopsis PLDP2, phospholipase D, which are involved in the catabolism of phospholipids, recycling P to essential metabolic processes and providing diacyglcerol for galactolipid biosynthesis (van der Rest et al, 2002;Li et al, 2006aLi et al, , 2006bTjellströ m et al, 2008). Transcripts with homology to proteins involved in the biosynthesis of galactolipids and sulfolipids also had significantly greater abundance at low [P] ext , including two isoforms of 1,2-diacylglycerol 3-b-galactosyltransferase (MGDG and MGDC) (Supplemental Table S2).…”