Phosphate-limited Oat

Abstract

We recently reported that cultivation of oat (Avena sativa L.) without phosphate resulted in plasma membrane phosphoglycerolipids being replaced to a large extent by digalactosyldiacylglycerol (DGDG) (Andersson, M. X., Stridh, M. H., Larsson, K. E., Liljenberg, C., and Sandelius, A. S. (2003) FEBS Lett. 537, 128 -132). We report here that DGDG is not the only non-phosphorouscontaining lipid that replaces phospholipids but that also the content of glucosylceramides and sterolglycosides increased in plasma membranes as a response to phosphate starvation. In addition, phosphate deficiency induced similar changes in lipid composition in the tonoplast. The phospholipid-to-glycolipid replacement apparently did not occur to any greater extent in endoplasmic reticulum, Golgi apparatus, or mitochondrial inner membranes. In contrast to the marked effects on lipid composition, the polypeptide patterns were largely similar between root plasma membranes from well-fertilized and phosphate-limited oat, although the latter condition induced at least four polypeptides, including a chaperone of the HSP80 or HSP90 family, a phosphate transporter, and a bacterial-type phosphoesterase. The latter polypeptide reacted with an antibody raised against a phosphate deficiency-induced phospholipase C from Arabidopsis thaliana (Nakamura, Y., Awai, K., Masuda, T., Yoshioka, Y., Takamiya, K., and Ohta, H. (2005) J. Biol. Chem. 280, 7469 -7476). In plasma membranes from oat, however, a phospholipase D-type activity and a phosphatidic acid phosphatase were the dominant lipase activities induced by phosphate deficiency. Our results reflect a highly developed plasticity in the lipid composition of the plasma membrane and the tonoplast. In addition, phosphate deficiency-induced alterations in plasma membrane lipid composition may involve different sets of lipid-metabolizing enzymes in different plant tissues or species, at different stages of plant development and/or at different stages of stress adjustments.

Phospholipase DZ2 plays an important role in extraplastidic galactolipid biosynthesis and phosphate recycling in Arabidopsis roots

“…6). In agreement with this hypothesis, it has been recently demonstrated that DGDG accumulation is highly up-regulated by Pi starvation in the plasma membrane fraction of oat roots and that PLD-type and PAP activity are the major lipase activities induced by Pi starvation in nonplastidic root membranes (20,27).…”

“…Although the participation and induction of genes involved in SQDG (SQD1 and SQD2), DGDG (DGD1 and DGD2), and MGDG (MGD2 and MGD3) biosynthesis in both roots and leaves as a response to Pi starvation have been experimentally demonstrated (12,13), no direct evidence has been reported to our knowledge on the existence of specific phospholipases that hydrolyze phospholipids to provide DAG for the synthesis of nonphosphorus lipids. Two potential pathways for the hydrolysis of phospholipids to release Pi from its storage source and to produce DAG, the substrate for galactolipid synthesis, have been proposed: a direct pathway involving phospholipase C and an indirect pathway involving PLD and PAP activities (14,19,20). Microarray analysis showed that two genes encoding phospholipases are strongly induced during Pi deprivation in Arabidopsis: NPC4, a member of the PLC family, and PLDZ2.…”

Optical Manipulation Reveals Strong Attracting Forces at Membrane Contact Sites between Endoplasmic Reticulum and Chloroplasts

“…Envelope membranes were isolated from chloroplasts isolated from 9-to 10-day-old pea seedlings as described (19). Analyses of membrane components and marker enzyme activities were assayed as described previously (20).…”

Metabolic Remodeling of Membrane Glycerolipids in the Microalga Nannochloropsis oceanica under Nitrogen Deprivation

“…A stable amount of DGDG may be essential for structural and functional stabilization of the chloroplast and thus cell survival. As DGDG can be exported from the chloroplast to replace phospholipids in extraplastidial membranes under P-limited conditions (Sandelius et al, 2003;Andersson et al, 2005;Jouhet et al, 2007), we can't rule out that trafficking of DGDG from the chloroplast to other subcelluar organelles may occur under N-deprivation conditions, especially when the extraplastidic bilayerglycerolipids (e.g., PC and DGTS) are drastically decreased.…”