The effect of salt stress on the relative expression of CAT1 and ASX1 genes and some physiological traits in two varieties of tomato

In this research, in order to study some physiological and molecular traits such as the expression level of Catalase (CAT1) and Ascorbate Peroxidase (APX1) genes in two, CH-Falat and Rio Grande-S, varieties of tomato plant (Solanum lycopersicum L.), an experiment was designed in randomized complete block design. Salinity with the concentration of 0, 25, 50, 75 and 100 mM NaCl was applied in hydroponic culture. Plants RNA was extracted and cDNA was synthesized, then Real–Time PCR was carried out. The results showed that the relative expression of CAT1 has been increased in Rio Grande-S at all levels of salinity and in Falat-CH variety only up to 50 mM NaCl. The relative expression of APX1 has been decreased in Rio Grande-S up to 50 mM of salinity level and has been increased in 75 and 100 mM salinity levels. The relative expression of APX1 in Falat-CH variety has been increased up to 50 mM salinity level. Some physiological traits in salinity treatments were also studied and the results showed that in both varieties, by salinity increase from 0 to 100 mM NaCl, the amount of Na, Prolin, the soluble sugers were increased and the amount of K, and K/Na were decreased. The membrane stability index was decreased in salinity treatments comparing to control. The results of the molecular and physiological analysis showed that Rio Grande S variety in comparison to CH-Falat is more resistant under high level of salinity.