Effects of copper excess on growth, H2O2, production and peroxidase activities in maize seedlings (Zea mays L.).

Ten day old mays seedlings (Zea mays L., var. Aligreen) cultured in hydroponic medium were treated by toxic amounts of copper (50 and 100 microM of CuSO4) during seven days. Cupric stress induced changes in growth parameters: The matter productions were more reduced in roots than in shoots. Also, a significant decrease in shoot and root elongation was observed. On the other hand, excess of copper increased significantly endogenous H2O2 in the two investigated organs and induced changes in peroxidase activities. Our results showed that in shoots, inducibility of GPX (Guaiacol peroxidase, EC 1.11.1.7), CAPX (Coniferyl alcohol peroxidase, EC 1.11.1.4) and APX (Ascorbate peroxidase, EC.1.11.1.11) was highly significant after application of 100 microM of CuSO4. While, this effect was not observed in 50 microM Cu-stressed shoots, in roots, data showed that 50 microM of CuSO4 induced stimulation in GPX and APX activities but ACPX activity remains unchanged. In roots, by contrast, exposure to 100 microM Cu induced significant increase only in ACPX activity.