title: Drought stress affects chloroplast lipid metabolism in rape (Brassica napus) leaves.
abstract: Rape (Brassica napus L. var. Bienvenue) is a 16:3 plant which contains predominantly prokaryotic species of monogalactosyldiacylglycerol i.e. sn-1 C18, sn-2 C16 (C18/C16 MGDG). Rape plants were exposed to a restricted water supply for 12 days. Under drought conditions, considerable changes in lipid metabolism were observed. Drought stress provoked a decline in leaf polar lipids, which is mainly due to a decrease in MGDG content. Determination of molecular species in phosphatidylcholine (PC) and MGDG indicated that the prokaryotic molecular species of MGDG (C18/C16) decreased after drought stress while the eukaryotic molecular species (C18/C18) remained stable. Drought stress had different effects on two key enzymes of PC and MGDG synthesis. The in vitro activity of MGDG synthase (EC. 2.4.1.46) was reduced in drought stressed plants whereas cholinephosphotransferase (EC. 2.7.8.2) activity was not affected. Altogether these results suggest that the prokaryotic pathway leading to MGDG synthesis was strongly affected by drought stress while the eukaryotic pathway was not. It was also observed that the molecular species of leaf PC became more saturated in drought stressed plants. This could be due to a specific decrease in oleate desaturase activity.
authors.affiliation: Laboratoire de Physiologie Cellulaire et Moléculaire, Université Pierre et Marie Curie (CNRS UMR 7632, Tour 53, Case 154), 4 Place Jussieu, F-75252 Paris Cedex 05, France Laboratoire de Physiologie Végétale, Institut des Sciences de la Nature, Université des Sciences et de la Technologie Houari Boumédienne, BP 39, El Alia, Bab Ez Zouar, Alger, Algérie.
authors.forename: Ghouziel
authors.initials: G
authors.lastname: Benhassaine-Kesri
authors.forename: Fatiha
authors.initials: F
authors.lastname: Aid
authors.forename: Chantal
authors.initials: C
authors.lastname: Demandre
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Kader
authors.forename: Paul
authors.initials: P
authors.lastname: Mazliak