Le calcium peut-il protégerAtriplex halimussubsp.schweinfurthiicontre la toxicité du cadmium ?

Abstract

To cite this article: Bouzid Nedjimi (2009) Le calcium peut-il protéger Atriplexhalimus subsp. schweinfurthii contre la toxicité du cadmium ?, Acta Botanica Gallica, 156:3, 391-397, DOI: 10.1080/12538078.2009 des steppes salées algériennes) ont été cultivés en condition hydroponique pour étudier l'effet de l'addition du calcium (Ca) dans la solution nutritive sur des plantes stressées par 400 µM CdCl 2 . Les traitements utilisés sont: 1) la solution nutritive de base (T) ; 2) la solution nutritive contenant 400 µM CdCl 2 ; 3) 400 µM CdCl 2 supplémenté par 20 mM CaCl 2 (CdCl 2 + Ca*) ; 4) 400 µM CdCl 2 supplémenté par 40 mM CaCl 2 (CdCl 2 + Ca**). Les résultats obtenus ont montré que le Cd entraîne une inhibition de la croissance pondérale, une réduc-tion des pigments chlorophylliens ainsi qu'une diminution des teneurs en Ca et du fer tissulaires, avec une accumulation du Cd surtout dans la partie racinaire. L'addition simultanée du Cd et de Ca dans le milieu de culture améliore la production de biomasse végétale en concomitance avec une amélioration de la composition minérale de la plante (Ca et Fe), une diminution des teneurs en Cd tissulaire, avec une augmentation des contenus en pigments photosynthétiques. L'ensemble de ces résultats suggère que l'effet négatif du Cd sur certains processus de croissance peut être atténué par un apport adéquat en Ca dans le milieu de culture.Mots clés : Atriplex halimus -cadmium -calcium -chlorophylle -fer.Abstract.-Atriplex halimus subsp. schweinfurthii (native halophyte in Algerian salt steppes) was grown in hydroponic conditions to investigate the effectiveness of supplementary calcium (Ca) applied into nutrient solution on plants grown at high (400 µM) CdCl 2 concentration. Treatments were: 1) control: nutrient solution alone (T); 2) nutrient solution plus 400 µM CdCl 2 ; 3) nutrient solution and 400 µM CdCl 2 plus supplementary 20 µM Ca (CdCl 2 + Ca*); 4) 400 µM CdCl 2 plus additional mixture of 40 mM CaCl 2 in nutrient solution (CdCl 2 + Ca**). Plants subjected to high CdCl 2 level exhibited a severe chlorosis, accompanied by a significant biomass reduction. Calcium, iron and chlorophyll content of plants grown at high CdCl 2 were less than those at normal nutrient solution. Supplementary Ca ameliorated the negative effects of Cd on plant growth, chlorophyll, Ca and Fe contents. Cadmium concentration in plant tissues increased in both shoots and roots at high CdCl 2 level, but it was reduced partially by supplementary Ca. These results indicate that calcium can protect A. halimus from Cd toxicity.

Overexpression of bacterial γ‐glutamylcysteine synthetase mediates changes in cadmium influx, allocation and detoxification in poplar

“…The higher net Cd 2+ influxes into the roots of the transgenics compared with wild-type poplars at the optimum Ca 2+ concentration suggests that the net Cd 2+ uptake in transgenics is more sensitive to changes in the exogenous Ca 2+ concentration. No information is available on the effects of changes in the Ca 2+ concentration on the net Cd 2+ fluxes in plant roots, but previous studies suggest that exogenous Ca 2+ can affect Cd accumulation in plants and attenuate Cd 2+ phytotoxicity (Kim et al, 2002;Nedjimi, 2009;Hayakawa et al, 2011;Wan et al, 2011). For example, the addition of exogenous Ca 2+ resulted in higher Cd concentrations in the roots but less Cd accumulation in the aerial parts of a woody species, Gamblea innovans (Hayakawa et al, 2011).…”

Phytoremediation: a sustainable environmental technology for heavy metals decontamination

“…Arsenic (As), lead (Pb), mercury (Hg), cadmium (Cd), nickel (Ni), chromium (Cr) and aluminum (Al) are the principal HMs, which cause toxicity to both flora and fauna in soil ecosystems. Most of these metals are easily stocked in plants, enter in the food chain and get transferred to the humans, which cause serious disorders and diseases [12,134]. Despite the fact that some of HMs such as iron (Fe), copper (Cu), selenium (Se) and zinc (Zn) are indispensable in small concentrations, but their accumulation at higher levels may become very toxic in the environment [11,115] (Table 1).…”

“…Plants growing in polluted soils exhibit several strategies to coping with the toxicity of HMs including preventing their accumulation, detoxification or metal excretion from the tissues [83]. The ability of hyper-accumulator plants to growth normally under high HMs levels is related to multiple biochemical pathways that enable to maintain metals concentrations at a lower level in the cytoplasm than in the soil, which protects the cytoplasmic organelles from toxic effect of HMs (vacuolar compartmentalization) [134]. Includer plant species which have no exclusion strategy assimilate and translocate high quantities of HMs and stock them in their shoots without signs of toxicity [120].…”

“…For a long time, humans have supplemented great quantities of pollutants to the soil, water and atmosphere biotopes as a consequence of industrial activities, such as mining of ores, gas emission, pesticide application and municipal waste production [168]. These pollutants can be accumulated in food chains, causing harmful effects on plants, animals and humans (damage to the endocrine system, impact on immunity, neurological disorders and cancer) [134].…”

Ca alleviated Cd-induced toxicity in Salix matsudana by affecting Cd absorption, translocation, subcellular distribution, and chemical forms

“…Calcium (Ca) is essential for plant growth and reduces plant Cd adsorption by competing with Cd [13,14]. Ca is fundamentally important for membrane permeability and maintaining cell integrity and ion uptake, which allows solute diffusion in plant tissues [15].…”