Farnoosh Attar - Department of Biology, Food & Agricultural Faculty, Standard Research Institute,
Fakhri Sadat Hosseini
Marjan Heidarzadeh

Salinity as one of the most important environmental crises alters general metabolic processes and enzymatic activities, causing oxidative stress in several plant species. In order to investigate the effects of salinity stress on plants, an in vitro study was conducted on the morphological parameters and superoxide dismutase (EC 1.15.1.1) (SOD) activity in the Crocus sativus L. (saffron) corms as a plant model exposed to salt stress. Dormant corms were cultivated in liquid medium in the presence of different concentrations (0-2 M) of NaCl and KCl. Roots and shoots, were measured at 3, 6, 10, 20, and 30 days of rooting. Total SOD activity was monitored spectrophotometrically at 550 nm, in phosphate buffer (pH 7.8) containing EDTA, xanthine, cytochrome c, extract, and xanthine oxidase. High salinities treatment (0.1-2 M), caused a severe decrease in the growth rate and in 1 or 2 M of each salt, no root growth was observed. SOD activity in corms rooted in up to 0.5 M NaCl was about 5 U/mg protein, but decreased to 1.82 ± 0.07 U/mg protein for corms rooted in 1 M NaCl. In corms rooted in KCl medium, SOD activity went from 5.84 ± 0.23 U/mg protein to 3.76 ± 0.28 and 1.7 ± 0.08 for corms rooted in 0.5 and 1 M KCl. Interestingly, SOD activity would be enhanced in vitro with increasing both of salts concentrations in the reaction mixture (~ 4.7 U/mg protein for 1 M KCl and 5.27 U/mg protein for 1 M NaCl), implying that the in vivo effect of salts on SOD activity was a complex and high salt stress in culture medium can inhibit the expression of SODs via activated signaling pathways.

salinity, corms, superoxide dismutase