CROSS-RESISTANCE BETWEEN WATER AND OXIDATIVE STRESSES IN WHEAT LEAVES

Seven-day-old leaves of two wheat cultivars, one resistant (Cruz Alta) and one sensitive (Leones) to water stress were subjected to 100% O2 and water stress in the light for 72 h. The aim of this work was to analyse the effects of both types of stress on the chloroplast antioxidant enzymes, glutathione reductase (GR) and ascorbate peroxidase (AP) and their relationship with stress resistance. Both GR and AP increased following 100% O2 and water stress in the resistant cultivar Cruz Alta only. Sulphydryl (SH) groups increased in the resistant cultivar and decreased significantly in the sensitive one under both stress treatments. Measurement of stress parameters (chlorophylls, proteins, lipid peroxidation and conductivity) revealed that oxidations caused by stress treatments appeared to be higher in the sensitive cultivar Leones than in the resistant Cruz Alta. It is suggested that there may be a link between GR, AP and oxidative protection. Some cross resistance between water and oxidative stresses in wheat leaves is also indicated.