square

Membrane Glycerolipid Remodeling Triggered by Nitrogen and Phosphorus Starvation in Phaeodactylum tricornutum

01/01/2015
Plant physiology
167 (1)

Type

Article dans des revues

Authors

Abida Heni
Dolch Lina-Juana
Meï Coline
Villanova Valeria
Conte Melissa
Block Maryse
Finazzi Giovanni
Bastien Olivier
Tirichine Leïla
Bowler Chris
Rébeillé Fabrice
Petroutsos Dimitris
Jouhet Juliette
Maréchal Eric

Diatoms constitute a major phylum of phytoplankton biodiversity in ocean and fresh water ecosystems. They are known to respond to some chemical variations of the environment by the accumulation of triacylglycerol, but the relative changes occurring in membrane glycerolipids has not yet been studied. Our goal was first to define a reference for the glycerolipidome of the marine model diatom Phaeodacylum tricornutum, a necessary prerequisite to characterize and dissect the lipid metabolic routes that are orchestrated and regulated to build up each subcellular membrane compartment. By combining multiple analytical techniques, we determined the glycerolipid profile of Phaeodactylum grown with various levels of nitrogen or phosphorus supplies. In different Phaeodactylum accessions collected worldwide, a deprivation of either nutrient triggered an accumulation of triacylglycerol, but with different time scales and magnitudes. We investigated in depth the effect of nutrient starvation on the Pt1 strain (culture collection CCAP 1055/3). Nitrogen deprivation was the more severe stress, triggering thylakoid senescence and growth arrest. By contrast, phosphorus deprivation induced a stepwise adaptive response. The timescale of the glycerolipidome changes and the comparison with large scale transcriptome studies were consistent with an exhaustion of unknown primary P-storage molecules (possibly polyphosphate) and a transcriptional control of some genes coding for specific lipid synthesis enzymes. We propose that phospholipids are secondary P-storage molecules broken down upon P deprivation, while non-phosphorus lipids are synthesized consistently with a phosphatidylglycerol-to-sulfolipid and a phosphatidycholine-to-betaine lipid replacement followed by a late accumulation of triacylglycerol. test lien