Effect of cadmium pollution on mobilization of embryo reserves in seedlings of six contrasted Medicago truncatula lines. (March 2015)

• Record Type: Journal Article
• Authors: Rahoui, Sondès; Chaoui, Abdelilah; Ben, Cécile; Rickauer, Martina; Gentzbittel, Laurent; El Ferjani, Ezzeddine
• Is Part Of: Phytochemistry. Volume 111(2015:Mar.)
• Page Start: 98
• Page End: 106
• Publication Date: 2015-03
• Subjects: Cd cadmium -- Dry wt dry weight -- FAAS free amino acids -- Fru fructose -- Fr wt fresh weight -- Glc glucose -- MtMST Medicago truncatula monosaccharide transporter -- Suc sucrose -- TSS total soluble sugars -- Tub tubuline -- Ubq ubiquitine; Amino acids -- Cadmium -- Carbohydrates -- Medicago truncatula -- Solute leakage -- Sugar transport -- Root growth; Botanical chemistry -- Periodicals; Biochemistry -- Periodicals; Botany -- Periodicals; Chimie végétale -- Périodiques; 572.2
• DOI: 10.1016/j.phytochem.2014.12.002
• Languages: English
• ISSNs: 0031-9422

Abstract

Graphical abstract: Tolerance order and growth inhibition in Medicago truncatula genotypes could be correlated to reserves mobilization disorders, their leakage in germination media and Mt MST expression alteration. Highlights: Cd induced nutritional disorders in Medicago truncatula genotypes. Mineral elements distributions changed regardless to line susceptibility to cadmium. Organic reserve mobilization changed with a genotype dependant pattern. Membrane integrity was altered in agreement with solute leakages in imbibition media. Mt MST gene expression evolved as a stress response. 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 Mt MST, 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.