The correlation between antioxidant enzyme activities and lipid peroxidation levels in Mentha pulegium organs grown in Ca2+, Mg2+, Cu2+, Zn2+ and Mn2+ stress conditions

The variations of antioxidant enzyme activities and lipid peroxidation (LPO) levels were investigated in all Mentha pulegium organs grown in the excess and absence of Ca2+, Mg2+ as macronutrients; Cu2+, Zn2+ and Mn2+ as micronutrients and control conditions. The decreasing of all antioxidant enzyme activities from roots to leaves, except for ascorbate-dependent peroxidase (AsA-dep POD) and guaiacol-dependent peroxidase (Gua-dep POD) activities under Ca2+ stress conditions Caused increases of LPO levels under both Ca2+ and Mg2+ stress conditions. Absence of Ca2+, Mg2+ and Zn2+ caused higher values of Superoxide dismutase (SOD) and catalase (CAT) in all organs of M. pulegium than control and maximum increases were obtained in roots Lis 213.6+/-4.2 and 45.5+/-1.3 IU mg(-1); 139.9+/-2.7 and 29.2+/-0.5 IU mg(-1); 140.4+/-3.0 and 28.0+/-0.6 IU mg(-1) in the absence of Ca2+ Mg2+ and Zn2+, respectively. Whereas the activities increased above control levels under excess Ca2+ and Mg2+ stress conditions, the values were lower than control under excess Zn2+ conditions. Whereas AsA-dep POD activities in Ca2+, Mg2+ and Zn2+ stress conditions were usually lower than control, the lower Gua-dep POD activity values were obtained only in leaves. All these antioxiclant enzyme activities correlated positively with increasing Cu2+ concentrations in all M. pulegium organs. SOD and CAT activities under excess Mn2+ conditions were higher, whereas they were lower in the absence of Mn2+ than control. AsA-dep and Gua-dep POD activities were inversely related to SOD and CAT activities. All of stress conditions caused higher LPO levels in all M. pulegium organs than control, except for roots under Ca2+ stress conditions. Whereas absence of Ca2+ and Mg2+ caused maximum LPO levels in leaves, the maximum increases were obtained Under excess of Cu2+, Zn2+ and Mn2+ in roots. (C) 2003 Elsevier Ireland Ltd. All rights reserved.