Banding Patterns Activity of Antioxidant Enzymes and Physiological Indices in the Maize (Zea mays L.) Genotypes under Water Deficit Stress

Various environmental stresses, especially water deficit stress have several and major effects on maize growth and production. Drought is one of the abiotic stresses that due to the great variety of rainfall conditions, it is known from Iran as the most important factor limiting the growth and production of crops. Therefore, the effect of water deficit stress on strategic plants such as maize is of particular importance.

In order to assess the effect of water-deficit stress on the activity of antioxidant enzymes and agro-physiological indices in the leaves in some of maize genotypes, a split-plot field experiment was conducted with three replications based on the Randomized Complete Block design (RCBD) was performed under field condition, it was performed on the farm of the Faculty of Agriculture, University of Tabriz. Three levels of irrigation (well-watered, intermediate and severe water-deficit stress) and 11 maize genotypes were considered as the main and sub-factors, respectively. After treatment, the electrophoretic analysis of three enzymes in maize leaves including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were carried out on 8% horizontal acrylamide gel and some agro-physiological indices such as malondialdehyde (MDA), H2O2, chlorophyll index (SPAD), relative water content (RWC) and soluble protein content were measured.

Based on the our results, CAT enzyme increased by 100% under severe stress compared to well-watered and MDA content with 120.78% increase, the highest increase activity and leaf chlorophyll under severe water deficit stress showed the highest reduction(-24.05%) compared to well-watered condition. In general, the soluble protein content fluctuated with increasing stress intensity compared to well-watered condition, On the other hand, the difference between the total soluble protein content in the two genotypes SC704 and SC706 with increasing intensity of stress from normal to intermediate stress and severe stress showed the least significant difference inversely.

Examination of maize genotypes with antioxidant enzymes and physiological indices showed that SC704, SC703, AR70 and SC706 genotypes had the highest level of antioxidant enzyme activity and adequate physiological response to water deficit stress, also they showed higher stress tolerance than water deficit stress. In both stressful conditions, SC260 genotype showed the highest susceptibility under water deficit stress condition. Finally, CAT, POX1, SOD1 and SOD2 isozymes as well as H2O2 indices, soluble protein content and leaf chlorophyll could be introduced as efficient isozymes and indices and can be these indices were used to identify superior genotypes under water deficit stress in maize molecular breeding programs.