Effect of Bioaccumulation of Cadmium on Biomass Productivity, Essential Trace Elements, Chlorophyll Biosynthesis, and Macromolecules of Wheat Seedlings

Abstract

Soil contamination with heavy metals has become a worldwide problem, leading to losses in agricultural yield and hazardous human health effects as they enter the food chain. The present investigation was undertaken to examine the influence of cadmium (Cd2+) on the wheat (Triticum aestivum L.) plant. Cd2+ accumulation and distribution in 3-wk-old seedlings grown in nutrient medium containing varying concentrations of Cd2+ (control, 0.25, 0.50, 1.0, 2.5, and 5.0 mg/L) was monitored. The effect of varying Cd2+ concentrations up to 21 d on biomass productivity, plant growth, photosynthetic pigments, protein, amino acids, starch, soluble sugars, and essential nutrients uptake was studied in detail to explore the level up to which the plant can withstand the stress of heavy metal. Plants treated with 0.5, 1.0, 2.5, and 5.0 mg/L Cd2+ showed symptoms of heavy-metal toxicity as observed by various morphological parameters which were recorded with the growth of plants. The root, shoot-leaf length and the root, shoot-leaf biomass progressively decreased with increasing Cd2+ concentration in the nutrient medium. Cd2+ uptake and accumulation was found to be maximum during the initial growth period. Cd2+ also interfered with the nutrients uptake, especially calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe2+), zinc (Zn2+), and manganese (Mn2+) from the growth medium. Growth reduction and altered levels of major biochemical constituents such as chlorophyll, protein, free amino acids, starch, and soluble sugars that play a major role in plant metabolism were observed in response to varying concentrations of Cd2+ in the nutrient medium. In the present study, the effects of Cd2+ on growth, biomass productivity, mineral nutrients, chlorophyll biosynthesis, protein, free amino acid, starch, and soluble sugars in wheat plants was estimated to establish an overall picture of the Cd2+ toxicity at structural and functional levels.

Cellular Response of Pea Plants to Cadmium Toxicity: Cross Talk between Reactive Oxygen Species, Nitric Oxide, and Calcium

“…In this work, long-term growth with 50 mM CdCl 2 produced a decrease in the contents of Ca, Cu, Fe, Mn, and Zn in pea leaves. Similar results have been observed previously in the same species ) as well as in other plant species (Salt et al, 1995;Gussarson et al, 1996;Shukla et al, 2003;Azevedo et al, 2005). On the contrary, sulfur was accumulated 3-fold in Cd-treated plants with respect to the control plants.…”

Photosynthetic organisms and excess of metals

“…When toxic metals and beneficial elements enter the cell together, the beneficial part may be too weak because of competition (Ernst et al 2000, Parker et al 2000, Shukla et al 2003, Vaillant et al 2004, Mendoza-Cózalt and Moreno-Sánchez 2005. It happens actually for Fe (Wallace et al 1992, Sárvári et al 1999.…”

“…The most documented impact of HMs on chloroplasts is certainly that induced by Cd (Sanità di Toppi and Gabbrielli 1999). Inhibition of photosynthesis by sub-lethal Cd 2+ concentrations has been described for various species, from cyanobacteria to higher plants (Malik et al 1992, De Filippis and Ziegler 1993, Vassilev et al 1995, Voigt et al 1998, Baryla et al 2001, Shukla et al 2003.…”

Effect of selenium on macro- and microelement distribution and physiological parameters of rape and wheat seedlings exposed to cadmium stress

“…Furthermore, heavy metals released from anthropogenic sources may end up in soil and enter the food web. Increased concentrations of cadmium (Cd) in the environment have given rise to serious concern, because in the form of Cd 2+ cation it is highly mobile in soil and toxic to plants, animals and humans (Shukla et al 2003;de la Rosa et al 2004). It has no metabolic role, but it inhibits e.g.…”