Alleviation of nickel toxicity in wheat (Triticum aestivum L.) seedlings by selenium supplementation

Abstract

Hydroponically grown wheat seedlings were treated with 50 μM Ni and/or 15 μM Se. After a 7-day culture period, their growth parameters, Ni, Se, Fe, and Mg contents, electrolyte leakage, photosynthetic pigment concentrations, and photochemical activity of photosystem II were determined. Exposure of wheat seedlings to Ni alone resulted in reduction in the total shoot and root lengths, by 22% and 50%, respectively. Addition of Se to the Ni-containing medium significantly improved the growth of these organs, compared to the seedlings subjected to Ni alone. Application of Se decreased the accumulation of Ni in shoots and roots and partially alleviated the Ni-induced decrease in Fe and Mg concentations in shoots. Electrolyte leakage increased in response to Ni stress, but in shoots it was diminished by Se supplementation. Exposure to Ni led to a decrease in chlorophyll a and b contents and enhancement of chlorophyll a/b ratio, but did not influence the concentration of carotenoids. Enrichment of the Ni-containing medium with Se significantly increased chlorophyll b content, compared to the seedlings treated with Ni alone. Photochemical activity, estimated in terms of the maximum quantum yield of photosystem II, decreased in response to Ni treatment but was significantly improved by simultaneous addition of Se. Results of our study suggest that alleviation of Ni toxicity in wheat seedlings by Se supplementation may be related to limitation of Ni uptake.