title: [Cadmium effects on lipid metabolism of rape (Brassica napus L.)].
abstract: Treatment of rape seedlings with increasing CdCl2 concentrations in the culture medium resulted in a cadmium accumulation within plant tissues, which increased with external metal dose; such accumulation was more important in roots than in leaves. Biomass production was severely inhibited, even at low cadmium concentration. In leaves, quantities of chloroplastic lipids, monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfolipids (SL) and phosphatidylglycerol (PG) decreased sharply under metallic treatment. However, contents of extrachloroplastic lipids, mainly phosphatidylcholine (PC) and phosphatidylethanolamine (PE) increased significantly. In contrast to leaves, contents of root phospholipids decreased. Likewise, levels of tri-unsaturated fatty acids: linolenic (C18:3) and hexadecatrienoïc (C16:3) dropped in leaves of treated seedlings as compared to those of controls, suggesting that heavy metals induced an alteration in the fatty acid desaturation process or a stimulation of their peroxidation. Also, trans palmitoleic acid (C16:1-trans) level in PG decreased considerably. In roots, there was a slight decrease in C18:3 level, with a concomitant increase in the C18:2 percentage. Radioactive labelling of leaf lipids with (1-14C) acetate allowed to show that fatty acid biosynthesis was noticeably altered at the highest cadmium dose used (50 microM). Biosynthesis of tri-unsaturated fatty acids was also inhibited which may explain the decline in non-labelled lipid contents. Results showed that metallic ion seems to affect selectively chloroplastic membranes due to an inhibition of polyunsaturated fatty acid biosynthesis. Moreover, a lipid peroxidation occurred in our case because of the spectacular increase of malondialdehyde (MDA) content observed in cadmium treated leaves.
authors.affiliation: Laboratoire Caractérisation et qualité de l'huile d'olive, INRST, BP 95-2050 Hammam-Lif, Tunisie.
authors.forename: Nabil
authors.initials: N
authors.lastname: Ben Youssef
authors.forename: Issam
authors.initials: I
authors.lastname: Nouairi
authors.forename: Sonia
authors.initials: S
authors.lastname: Ben Temime
authors.forename: Wael
authors.initials: W
authors.lastname: Taamalli
authors.forename: Mokhtar
authors.initials: M
authors.lastname: Zarrouk
authors.forename: Mohamed Habib
authors.initials: MH
authors.lastname: Ghorbal
authors.forename: Douja
authors.initials: D
authors.lastname: Ben Miled Daoud
mesh_terms: D029688:Brassica napus / Q000187:drug effects / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology*; D019256:Cadmium Chloride / Q000494:pharmacology; D050356:Lipid Metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development
chemical_list: D002104:Cadmium; D019256:Cadmium Chloride