The effect of aluminium on enzyme activities in two wheat cultivars
In order to study the effect of different aluminum (Al) concentrations on the enzyme activities of wheat seedlings and the effect of malate and citrate treatments as chelates for reducing the noxious effect of Al in medium culture, the seedlings of two wheat cultivars, Darab (Al-sensitive) and Maroon (Al-tolerant) were grown on hydroponic solution (non modified Hoagland solution) containing AlCl3 (0-100-200-300 M). Factorial experiment was realized in a complete randomized design with three replications. The activity of different enzymes such as ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and superoxide dismutase (SOD) in root and shoot were measured. Analysis of variance revealed that, the activity of studied enzymes (APX, CAT, GR and SOD) in root and shoot were affected by the main effects of Al concentration. However, in the case of catalase activity in root, the main effect of genotypes as well as genotype´Al concentration was also significant. APX activity in root was not significantly differed between Maroon and Darab in all Al concentrations. But by increasing Al concentration in root medium APX activity was significantly decreased. In the case of SOD activity, we did not find any difference between the studied genotypes in all Al concentrations but its content in roots was affected by the amount of Al applied in medium. So that by increasing the amount of Al, SOD content increased in the genotypes similarly. The same trend was observed for catalase activity in root. In the case of GR activity, we did not find any difference between the genotypes in all Al concentrations but its content in root was affected by applying Al in medium compared with control medium, so that GR content increased in both genotypes similarly. The activity of investigated enzymes showed the same trend in the shoot. The effect of malate and citrate was also studied on reducing the noxious effect of Al in root. Analysis of variance revealed that, there were significant differences within the treatments on the enzymes activity in root (not in the shoot) except for catalase. However, some interaction effects were significant. This means that malate or citrate application was effective in some Al concentrations.
Key words: Maroon (Al tolerant), Darab (Al sensitive), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD).