title: Effect of cadmium pollution on mobilization of embryo reserves in seedlings of six contrasted Medicago truncatula lines.
abstract: Six Medicago truncatula genotypes differing in cadmium susceptibility were used to test the effect of this heavy metal on mineral, carbohydrate and amino acid supply in growing radicles. Cadmium treatment caused alteration of macronutrient (Ca and K), microelement (Fe, Zn and Cu), carbohydrate (total soluble sugars (TSS), glucose, fructose and sucrose) and free amino acid (FAAS) accumulations. These mobilization changes differed in the tested genotypes. Carbohydrates were determining to susceptible lines' growth in control condition; free amino acids enabled tolerant lines to counteract cadmium intrusion. Transcriptional changes in response to cadmium treatment were analyzed on MtMST, a gene encoding a monosaccharide transport protein. A significant down-regulation was observed in the most susceptible line TN1.11. Glucose was over-consumed in tolerant lines. Thus, glucose metabolism integrity seems essential to maintain growth under cadmium exposure. Analysis of germination medium showed solute losses at the expense of suitable mobilization to the growing embryonic axis and highlights cadmium-triggered membrane alterations. FAAS and TSS leakages were reduced in tolerant lines while monosaccharide losses were accentuated in susceptible lines. This research work gave an overview of cadmium deleterious effects on biomass mobilization and membrane integrity. Carbon metabolism is shown to be primordial to enhance early embryonic growth and nitrogen metabolism is revealed to be crucial to establish seedling growth under cadmium stress.
authors: Toxicologie Végétale & Biologie Moléculaire des Microorganismes, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia; Université de Toulouse, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, 18 chemin de Borde Rouge, 31326 Castanet Tolosan, France. Electronic address: rahoui.sondes@yahoo.fr.
authors: Sondès
authors: S
authors: Rahoui
authors: Toxicologie Végétale & Biologie Moléculaire des Microorganismes, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia.
authors: Abdelilah
authors: A
authors: Chaoui
authors: Université de Toulouse, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, 18 chemin de Borde Rouge, 31326 Castanet Tolosan, France; CNRS-EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 31326 Castanet-Tolosan, France.
authors: Cécile
authors: C
authors: Ben
authors: Université de Toulouse, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, 18 chemin de Borde Rouge, 31326 Castanet Tolosan, France; CNRS-EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 31326 Castanet-Tolosan, France.
authors: Martina
authors: M
authors: Rickauer
authors: Université de Toulouse, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, 18 chemin de Borde Rouge, 31326 Castanet Tolosan, France; CNRS-EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 31326 Castanet-Tolosan, France.
authors: Laurent
authors: L
authors: Gentzbittel
authors: Toxicologie Végétale & Biologie Moléculaire des Microorganismes, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia.
authors: Ezzeddine
authors: E
authors: El Ferjani
mesh_terms: D000596:Amino Acids / Q000032:analysis; D018533:Biomass; D002104:Cadmium / Q000494:pharmacology*; D002118:Calcium / Q000032:analysis; D050260:Carbohydrate Metabolism / Q000187:drug effects; D002241:Carbohydrates / Q000032:analysis; D002244:Carbon / Q000378:metabolism; D002460:Cell Line; D003300:Copper / Q000032:analysis; D004787:Environmental Pollution / Q000009:adverse effects*; D018525:Germination / Q000187:drug effects; D007501:Iron / Q000032:analysis; D046913:Medicago truncatula / Q000737:chemistry* / Q000235:genetics; D011188:Potassium / Q000032:analysis; D036226:Seedlings / Q000187:drug effects*; D015032:Zinc / Q000032:analysis
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D002104:Cadmium; D002244:Carbon; D003300:Copper; D007501:Iron; D015032:Zinc; D011188:Potassium; D002118:Calcium
keywords: Amino acids; Cadmium; Carbohydrates; Medicago truncatula; Root growth; Solute leakage; Sugar transport