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Juliette Jouhet

Lipid remodeling in plant cell in phosphate deprivation

Published on 25 November 2005

Thesis presented November 25, 2005

Phosphate is often a limiting factor for plant growth in soil. In plant cell, phosphate deprivation induces a decrease of phospholipid amount, mobilizing phosphate present in theses molecules. This decrease is compensated by an increase of non phosphorous plastidic glycolipid amount such as digalactosyldiacylglycerol (DGDG). We have shown that under phosphate deprivation a part of phospholipids is transformed into phosphatidylcholine (PC), producing a transitory increase of PC in short time of deprivation. Then, PC is hydrolyzed into diacylglycerol (DAG) that increases and feeds DGDG synthesis. Our results suggest a direct transfer of DAG from non plastidic membranes to plastid envelope, where DGDG synthesis is located. Then, newly synthesized DGDG is exported to extraplastidic membranes. We have shown that DGDG is present in mitochondria and is transferred from plastids to mitochondria by contact between specialized plastid envelope domains and mitochondria outer membrane. Finally, in order to identify proteins involved in lipid remodeling, we collaborated to a transcriptomic analysis of Arabidopsis thaliana genome under phosphate deprivation. We have selected from this analysis a phospholipase D, PLD
ζ2, that is likely involved in intracellular amount of inorganic phosphate and in PC hydrolysis for DAG feeding of galactolipid synthesis.

Lipid, DGDG, plastid envelope, mitochondria, remodeling​, membrane, traffic, phosphate

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