Impact of drought and leaf development stage on enzymatic antioxidant system of two<i>Populus deltoides</i>×<i>nigra</i>clones

Abstract

Impacts of mild and severe water constraints were investigated on leaf protein content and activities of superoxide dismutase (SOD), catalase and peroxidase in young cuttings of two Populus deltoides nigra clones, 'Luisa_Avanzo' and 'Dorskamp', known to differ in their level of drought tolerance. Expanding and mature leaves were analyzed separately. The effect of water deficit on enzymatic antioxidant system depended on both clone and leaf development stage. For 'Dorskamp', which presents an higher drought tolerance than 'Luisa_Avanzo', activities of SOD and catalase increased in response to the severe water deficit in mature leaves only. For 'Luisa_Avanzo', peroxidase activity increased in response to the mild water deficit in expanding leaves merely. For both clones, three different SOD isoforms, Mn-SOD, Fe-SOD and Cu/Zn-SOD were detected in various amounts depending on drought intensity.