Responses of Nonprotein Thiols to Stress of Vanadium and Mercury in Maize (Zea mays L.) Seedlings.

The heavy metal pollution in ecosystems is of increasing global concern. This study investigated firstly the responses of phytochelatins (PCs), glutathione (GSH) and other nonprotein thiols (NPT) in maize seedlings under vanadium (V), mercury (Hg) or their combined stress. With V or V-Hg combined stress, the contents of PCs, GSH and NPT in shoots and roots both increased with increasing the V stress level, and reached the maximum when the V stress level was 5 mg/L. Accumulation of V in all organs of maize seedlings was in sequence as follows: roots ≫ shoots, while Hg inhibited the accumulation of V. Results show that the root of plant has stronger tolerance to V, and the low V stress level can promote the synthesis of thiol groups to reduce the toxicity of Hg for plants.