Interactions of zinc and cadmium toxicity in their e ects on growth and inantioxidative systems in tomato plants (Solanum lycopersicum)
Jaouhra Cherif , Chamseddine Mediouni , Wided Ben Ammar , Fatma Jemal
DOI:
Received April 09, 2010,Revised June 04, 2010, Accepted , Available online
Volume 23,2011,Pages 837-844
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The interaction between zinc and cadmium was investigated in tomato plants (Solanum lycopersicum). Ten-day-old seedlings were
treated with 10 mol/L CdCl2 associated to di erent concentrations of ZnCl2 (10, 50, 100, and 150 mol/L). Zn supply clearly reduced
Cd accumulation in leaves and simultaneously increased Zn concentration. Cd induced oxidative stress in leaves as indicated by an
increase in thiobarbituric acid-reactive substances (TBARS) level and chlorophyll breakdown. Furthermore, compared with control, Cdtreated
plants had significantly higher activities of superoxide dismutase (SOD, EC 1.15.1.1), whereas, catalase (CAT, EC 1.111.1.6),
ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) activities were significantly suppressed by Cd
addition. Zn supplementation, at low level, restored and enhanced the functional activity of these enzymes (SOD, CAT, APX and GR) as
compared to Cd-alone-treated plants. The beneficial e ect of adequate Zn level on Cd toxicity was confirmed by a significant decrease
in TBARS level and restoration of chlorophyll content. However, when Zn was added at high level in combination with Cd there was an
accumulation of oxidative stress, which was higher than that for Cd or excess Zn alone treatments. These results suggested that higher
Zn concentrations and Cd are synergistic in their e ect on plant growth parameters and oxidative stress.
