Evidence for a different metabolism of PC and PE in shoots and roots.
We investigated phosphatidylcholine (PC) and phosphatidylethanolamine (PE) labelling in shoots and roots from leek plantlets, maize seedlings and Arabidopsis thaliana through the incorporation of radiolabelled acetate. Regardless of the pathway followed in shoots, PC labelling was always higher than PE labelling. However, we obtained an opposite situation in leek and A. thaliana roots since PC labelling was much lower than PE labelling. Several hypotheses to explain the origin(s) of these discrepancies between roots and shoots were tested. Among them, neither the level of the respective AAPT activities, nor specific regulations of PC biosynthesis through the mRNA levels of several enzymes (choline citidylyltransferase (CCT), ethanolamine citidylyltransferase (ECT), phosphoethanolamine methyltransferase (PEAMT)), nor the fatty acyl chain composition of PC, PE, and diacylglycerol, were responsible for the differences observed between PC and PE metabolism in roots and shoots. Finally, we investigated the acylation of PC and PE in vitro in both shoots and roots of A. thaliana seedlings, and demonstrated that some specific remodelling of PC and PE by acylation was responsible for the differences in labelling observed in vivo.
Hocquellet
Agnès
A
Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS-Université Victor Segalen Bordeaux-2, 146, rue Léo-Saignat, Case 92, 33076 Bordeaux cedex, France.
Joubès
Jérome
J
Perret
Anne-Marie
AM
Lessire
René
R
Moreau
Patrick
P
D000215:Acylation; D000490:Allium / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism; D001483:Base Sequence; D005227:Fatty Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D010713:Phosphatidylcholines / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D003313:Zea mays / Q000378:metabolism
D005227:Fatty Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D012333:RNA, Messenger; C483858:phosphatidylethanolamine