Abstract
BackgroundCadmium (Cd) is one of the most toxic heavy metals and inhibits physiological processes of plants. Potassium (K) is an essential macronutrient in plants. K deficiency and Cd stress represent two different abiotic stress conditions that occur in the field simultaneously. In this study, effects of K deficiency on antioxidant status and Cd toxicity in rice seedlings were investigated.ResultsK deficiency significantly decreased K concentration in shoots and roots. However, fresh weight and dry weight of rice seedlings were not affected by K deficiency. The activities of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase) in K-deficient leaves were higher than respective control leaves. However, K deficiency had no effect on the content of antioxidants (ascorbate and glutathione). Cd toxicity was judged by the decrease in biomass production, chlorosis, and induction of oxidative stress. Based on these criteria, we demonstrated that K deficiency protected rice seedling from Cd stress. Moreover, chlorophyll concentration was higher in K-deficient shoots and roots than their respective control shoots and roots.ConclusionsOur results indicated that K deficiency protects rice seedlings from Cd toxicity. This protective effect of K deficiency is mainly due to enhanced antioxidant enzyme activities but not inhibition of Cd uptake.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-2) contains supplementary material, which is available to authorized users.
Highlights
Cadmium (Cd) is one of the most toxic heavy metals and inhibits physiological processes of plants
Since young rice seedlings were used for the present study, the nutrient solution contained no silicon, silicon is essential for growth of sturdy rice plants in the field
Effect of K deficiency on growth response and K concentration To examine the effect of K deficiency on growth response and K concentration, rice seedlings were grown under conditions of sufficient and deficient K supply (−K) for 12 days
Summary
Cadmium (Cd) is one of the most toxic heavy metals and inhibits physiological processes of plants. Cadmium is a widespread metal contaminating many areas, either naturally or because of industrial use (Pan et al, 2010). Once Cd is taken up by plants, many cellular structures and metabolic processes are affected (Sanitá di Toppi and Gabbrielli, 1999; Gratǎo et al, 2005). Cd is a bivalent cation and unable to generate free radicals directly, the production of reactive oxygen species (ROS) after Cd exposure has been reported (Sanitá di Toppi and Gabbrielli, 1999; Gratǎo et al, 2005; Cuypers et al, 2010). Plants use antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), and catalase (CAT) as well as non-enzymatic antioxidants such as ascorbate (AsA) and glutathione (GSH) to scavenge ROS (Noctor and Foyer 1998; Amudha and Balasubnramani 2011; Foyer and Noctor, 2011)
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