Influences of calcium silicate on chemical forms and subcellular distribution of cadmium in Amaranthus hypochondriacus L.

Abstract

A pot experiment was conducted to investigate the effects of calcium silicate (CS) on the subcellular distribution and chemical forms of cadmium (Cd) in grain amaranths (Amaranthus hypochondriacus L. Cv. ‘K112’) grown in a Cd contaminated soil. Results showed that the dry weight and the photosynthetic pigments contents in grain amaranths increased significantly with the increasing doses of CS treatments, with the highest value found for the treatment of CS3 (1.65 g/kg). Compared with the control, application of CS4 (3.31 g/kg) significantly reduced Cd concentrations in the roots, stems and leaves of grain amaranths by 68%, 87% and 89%, respectively. At subcellular level, CS treatment resulted in redistribution of Cd, higher percentages of Cd in the chloroplast and soluble fractions in leaves of grain amaranths were found, while lower proportions of Cd were located at the cell wall of the leaves. The application of CS enhanced the proportions of pectate and protein integrated forms of Cd and decreased the percentages of water soluble Cd potentially associated with toxicity in grain amaranths. Changes of free Cd ions into inactive forms sequestered in subcellular compartments may indicate an important mechanism of CS for alleviating Cd toxicity and accumulation in plants.

Interplay of Calcium and Nitric Oxide in improvement of Growth and Arsenic-induced Toxicity in Mustard Seedlings

“…Moreover, high PCs content demands more GSH to counteract the stressed situation and also higher As accumulation stimulates NPTs for scavenging, by using available GSH pool; thus lower GSH content was obtained upon EGTA + LaCl 3 or c-PTIO + L -NAME supplementation to As + Ca treated seedlings (Table 2). Additionally, CaCl 2 and SNP treatment to As-stressed test seedlings also showed an improvement in the contents of thiol compounds thereby justifying their role in reducing As toxicity by promoting peptides and proteins to chelate metalloid, which is corroborated with earlier findings of Lu et al 36 and Praveen and Gupta 4 in Amaranthus hypochondriacus and Oryza sativa seedlings, respectively. Table S2 shows the correlation between treatments and tested parameters in the B. juncea L. seedlings.…”

“…The thiol compounds: Cys, NPTs and PCs act as first barrier against As toxicity thereby reducing the injurious effect to plants 2,4 . In the present investigation, the content of Cys, NPTs and PCs were found to increase under As stress and further enhancement was noticed when EGTA + LaCl 3 or c-PTIO + L -NAME were supplemented to As + Ca stressed seedlings (Table 2), which might be due to their demand for Fe-S cluster of photosynthetic apparatus 39 , protein synthesis, stabilizing tertiary structures of protein, synthesis of GSH, hydroxymethyl-PCs and other low molecular weight compounds 3,36 . Moreover, high PCs content demands more GSH to counteract the stressed situation and also higher As accumulation stimulates NPTs for scavenging, by using available GSH pool; thus lower GSH content was obtained upon EGTA + LaCl 3 or c-PTIO + L -NAME supplementation to As + Ca treated seedlings (Table 2).…”

“…The increased NO might have formed a less toxic peroxynitrite (ONOO − ) 16,35 or induced various ROS-scavenging enzyme activities like superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) (Figs. 5a-c) as was discussed by Siddiqui et al 15 and Lu et al 36 . Interestingly, c-PTIO and l-NAME application arrested the effect of Ca 2+ and NO in As-stressed seedlings, which was further confirmed by in-vivo staining for SOR, H 2 O 2 , lipid peroxidation and injury of plasma membrane integrity in leaf tissues ( Figs.…”

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

“…The addition of Ca effectively alleviated Cd toxicity in Cd-treated plants. A previous study indicated a internal mechanism for depressing the Cd toxicity as Ca concentrations increased in plant roots exposed to Cd, that when both Cd and Ca exist in the soil system, Ca and Cd exhibit similar chemical properties, Ca competes with Cd at adsorption sites in the soil, as a result, Cd uptake is reduced by Ca, then reducing Cd toxic effects in plants [7,13,20,23]. µM Cd.…”

“…In a previous investigation, 5 mM Ca alleviated the toxic effects of Cd on S. matsudana seedling growth and promoted the uptake of copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) to different degrees [7]. However, the Ca mechanism that affects Cd accumulation in plants remains to be Previous studies demonstrated that heavy metal subcellular localization, chemical forms and their mobility may be related to heavy metal detoxification and tolerance in plants [21][22][23][24][25]. Previous investigations also indicated that the stored forms of Cd in plant cells affect Cd uptake, accumulation and tolerance [25,26].…”