Effects of Cd~(2+) Stress on Ascorbate-Glutathione Cycle Metabolism in Tomato Seedlings

A solution culture experiment in greenhouse was carried out to study the dynamic change of ascorbate-glutathione cycle metabolism in roots and leaves of tomato seedlings under 0.05 mmol/L Cd~(2+) stress and recovery. The results showed that under stress malonaldehyde(MDA) contents in roots and leaves increased ,ascorbate peroxidase(APX)activity rose at the begining of three days and then decreased ,glutathione reductase(GR) activity decreased on the first day and then increased, the content of ascrobate(AsA) and glutathione(GSH) increased and the increase in roots was higher than that of leaves. After recovery the MDA content in leaves declined to control level, while the MDA content in roots duratively increased. The activities of APX and GR and the content of AsA and GSH could recover, which were higher than control. GSH contents in roots duratively maintain high level. There were defferences between the resumptive extent of parameters of leaves and roots.