Effect of exogenous hydrogen peroxide on peroxidase and polyphenol oxidase activities in cajanus cajan (l.) millsp. detached leaves

In this report peroxidase (POD) and polyphenol oxidase (PPO) activities were used to study the effect of hydrogen peroxide (H2O2) on leaf senescence in detached pigeonpea (Cajanus cajan [L.] Millsp.) leaves. The activities of POD and PPO were observed to be greater in H2O2-stressed pigeonpea leaves than in water treated control leaves. However, after longer incubations activities of these enzymes were markedly reduced. The observed changes revealed that exogenous H2O2 may induce oxidative stress tolerance by enhancing the activities of POD and PPOs. On the other hand, reduction found in H2O2-induced POD and PPO activities at later stages may be due to destruction of these proteins along with other proteins. This study will help to improve the tolerability of plants to environmental stresses by enhancing the expression of POD and PPOs.