Evaluation of the effect of salinity on the germination and expression of antioxidant genes in two cultivars of tomato plant

Environmental stresses are considered among the most important factors limiting agricultural production. Tomato, an important agricultural product, is sensitive to high salinity levels in soil. During salinity stress, several physiological phenomena occur in plants, including oxidative damage to cellular components due to ''reactive oxygen species'' or ROS production. Plants produce antioxidant enzymes such as catalase, ascorbate peroxidase and superoxide dismutase to counter the destructive effects of ROS. This study was carried out to evaluate the rate of germination and the expression of CAT1 and APX1 genes in two tomato cultivars, caljN3 and superstrain B. To evaluate the rate and the percentage of the germination, the seeds were cultured on filter paper in a completely randomized design with three replications and the rate and percentage of germination, radicle length and plumule length were measured after 15 days. To perform the molecular study, total RNA was extracted from plants grown in control conditions and under salinity stress. The results demonstrated that by increasing the salinity, reductions in germination percentage, germination rate, radicle length and plumule length were observed in both CaljN3 and Superstrain B cultivars, although the CaljN3 cultivar showed the lowest decrease. Interestingly, upon increasing the stress level, the rates of expression of the CAT1 and APX1 genes in the caljN3 cultivar were nearly twice and 10 times, respectively, higher than for the Superstrain B cultivar. These results could be one of the reasons for the superior growth and salt stress tolerance of caljN3 cultivar compared to SuperstrainB cultivar.