Effect of salt stress on antioxidant enzymes and lipid peroxidation in leaves in two contrasting corn, 'Lluteño' and 'Jubilee'

Salinity is an important problem to crop production; affecting photosynthesis process which favors the production of reactive oxygen species. Plants have generated adaptation strategies to prevent oxidative damage caused by salinity. In this study we evaluated the effect of salinity on lipid peroxidation and antioxidant enzymes in leaves of corn (Zea mays L.) plants 'Lluteño' (adapted to salinity) and 'Jubilee' (improved variety). 'Lluteño' is the only one corn capable to prosper in the Valley of Lluta under saline conditions (EC = 9.1 dS m^-1) and the most widely cultivated crop in terms of area in the desert of northern Chile. Plants of 21 d old were subjected for 15 d to two saline treatments: 50 and 100 mM NaCl. Salinity caused a significant reduction in plant biomass, ca. 65% in 'Jubilee' and 20% in 'Lluteño' (P ≤ 0.05). The biomass reduction and oxidative damage to cell membranes caused by the generation of peroxides was significantly less in 'Lluteño'. The activity of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX) in 'Lluteño' was significantly greater than in 'Jubilee' in all treatments, while glutathione reductase (GR) had greater activity in 'Jubilee'. However, most enzymes studied were adversely affected by salinity compared to the control. These results indicate that tolerance to salinity exhibited by 'Lluteño' should in part due to the high activity that exhibit antioxidant enzymes compared to 'Jubilee'.