Superoxide Dismutase Enzyme Expression in Root and Shoot of Triticale Seedlings under Drought Stress Conditions

Introduction: Triticale (X. Triticosecale Wittmack) was created by doubling the number of F1 hybrid chromosomes between wheat (Triticum spp.) as the female parent and rye (Secale spp.) as the male parent. Investigation of the plants reaction to water shortage is systematically considered by identifying features that are related to drought tolerance subjected to the physiological, cellular, biochemical, and molecular bases. One of the main subjects regarding plants damage under drought stress is the accumulation of reactive oxygen species. Plants possess enzymatic and non-enzymatic systems to prevent oxygen free radical damage which are using them in an adaptive way under drought stress condition. Changes in the expressional level of antioxidant enzymes and the concentration of these enzymes, as well as increasing their activity, are among the very important changes occurring in the cellular level as the result of facing drought stress. Considering the role of the superoxide dismutase enzyme in regulating the amount of oxygen free radicals in plant cells, the aim of the present study was to investigate the gene expression of the superoxide dismutase enzyme with copper/zinc coenzyme under drought stress conditions.
Materials and methods: Two genotypes of triticale (sensitive and tolerant) were subjected to drought stress conditions after establishment, and their aerial parts and roots were sampled at 0, 12, 36, and 72 hours after applying drought stress. Drought treatment was applied by weight based on the soil capacity of the pots and by daily weighing of the pots. Each time point repeated three times where the plant shoot was samples prior to plant root. This experiment was carried out in a factorial manner and with a completely randomized design in the greenhouse. The expression level of the superoxide dismutase gene with copper/zinc coenzyme was measured in the samples using the quantitative PCR method.
Results: The results of the present study showed that the expression of the Cu/Zn-SOD gene is affected and changed under stress conditions. In general,, with the increase in the amount of stress severity and time of stress, the amount of immediate gene expression increased. The changes in the expression of this gene were greater in the shoots than in the roots, and the shoots responded faster to drought stress. Also, between the two sensitive and tolerant genotypes used in this experiment, the level of Cu/Zn-SOD gene expression in both roots and shoots was higher in the tolerant genotype than in the sensitive triticale genotype.
Conclusion: According to the changes in expression and amount in two sensitive and tolerant triticale genotypes, it was generally determined that the superoxide dismutase enzyme is an essential enzyme in the plant to respond to drought stress and also to create tolerance in the triticale plant. Also, according to the changes in gene expression related to the Cu/Zn-SOD isozyme in triticale, it was determined that this isozyme is probably one of the active isozymes of the superoxide dismutase enzyme, whose expression is increased under drought stress conditions.