Changes in thiol content in roots of wheat cultivars exposed to copper stress
2002
Tari, I. | Lorincz, Z. (University of Szeged, Szeged (Hungary). Dept. of Plant Physiology) | Szalai, G. | Balint, A.
Wheat (Triticum aestivum) cultivars GK Tiszataj, Yubileinaya, GK Oethalom and a landrace Kobomugi were grown for 18 days in hydroponic cultures containing 0 (control), 0.1, 1.0 or 10.0 microM Cu2+. On a dry mass basis, Tiszataj and Kobomugi accumulated slightly more Cu2+ in the root tissues than did Yubileinaya and Oethalom, but their controls also contained higher amounts of Cu2+. As a result of perturbation in the plasma membrane functions the K+ content of roots was reduced at 10 microM Cu2+ in all cultivars, whereas the K+/Na+ ratio decreased significantly only in the roots of Oethalom. In the sensitive cultivar, Oethalom, the dry mass of the roots decreased while the cysteine content, which is a limiting factor for glutathione synthesis, did not satisfactorily increase with increasing tissue Cu2+ content. This suggests that in Oethalom the membrane damage of the root cells at 10 microM Cu2+ concentration may affect the sulphur availability or metabolism. Concentrations of glutathione and hydroxymethyl-glutathione, a tripeptide which may play a similar biochemical role to glutathione, were also lower in the sensitive cultivar. In the absence of glutathione the root tissues failed to cope with the oxidative stress caused by the excessive amount of Cu2+. A significant accumulation of iron in the roots of the sensitive cultivar at 10 microM Cu2+ supply enhanced the oxidative damage.
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