Responses of antioxidant gene and enzymes to salinity stress in the Cuminum cyminum L.

Abstract

Salt stress as a major limiting factor negatively affects many physiological processes in plants. Salinity promotes the generation of reactive oxygen species and subsequently oxidative damage of cellular components. Plant salt stress tolerance requires activation of antioxidative pathways to prevent plant cell from injurious effects. In this study real-time quantitative reverse transcription–polymerase chain reaction was used to determine the protective role of two antioxidant genes, i.e. iron-superoxide dismutase (Fe-SOD) and catalase (CAT) in Cuminum cyminum L. after their treatment with 50, 100, 150 and 200 mM NaCl. Enzymatic activities were assayed spectrophotometrically for three antioxidants. Moreover, growth parameters, protein content and proline accumulation were measured. In comparison with the control plants, those plants which were exposed to 50 and 100 mM NaCl concentration accumulated higher levels of proline. At 50, 100 and 150 mM of NaCl plants showed higher superoxide dismutase, ascorbate peroxidase and catalase activities. The same condition also induced expression of the Fe-SOD and CAT genes at mRNA level. Protein content of the treated plants was significantly decreased at 50 mM NaCl and remained constant at other concentrations. Whereas, the growth parameters, with one exception in case of shoot length, did not change at plants receiving low and mild salt concentrations of up to 150 mM NaCl, 200 mM of NaCl affected these parameters negatively. From these details, it can be concluded that C. cyminum respond to salt stress by antioxidant system efficiency and proline accumulation.