Antioxidative protection in a drought‐resistant maize strain during leaf senescence

Abstract

Leaves of 7‐ and 18‐day‐old plants of two maize strains, one resistant (LIZA) and one sensitive (LG11) to water stress, were floated in 1 mM paraquat and 1 mM H2O2 for 12 h in light and in darkness. The aim of this work was to analyse the effects of these substances on the activities of enzymes involved in the scavenging of active oxygen species during senescence. Three senescence parameters; chlorophyll loss, lipid peroxidation and conductivity; showed a general cell damage caused by both oxidative treatments and revealed a higher tolerance of LIZA than LG11 to paraquat and H2O2 both in light and in darkness. Activities of antioxidative enzymes increased by the effect of oxidative treatments in young and senescent leaves of the drought‐resistant maize strain LIZA. These increases were about 3‐to 6‐fold in glutathione reductase. 3‐to 4‐fold in superoxide dismutase and 2‐fold in ascorbate peroxidase activities. The possible correlation between water stress resistance. senescence and the potential of antioxidant enzymes was analysed.