Enzymatic and non-enzymatic antioxidant responses of two Mentha pulegium provenances to salt stress

Abstract

The aim of the present investigation was to evaluate the impact of moderate salinity in two Tunisian Mentha pulegium L. provenances differing in their salt sensitivity and to identify the antioxidant system responsible for the maintenance of plant vigor in the less sensitive provenance. Seedlings of the two provenances (Tekelsa and Soliman) were hydroponically grown at 0 and 35 mM NaCl over 15 and 45 days. Both the less (Soliman) and the more sensitive (Tekelsa) provenances behaved as a sensitive glycophyte not able to tolerate such a moderate salinity. But, Soliman showed less lipid peroxidation and electrolyte leakage since it restricted sodium uptake and accumulation into its tissues. In addition, lipid peroxidation and electrolyte leakage drastically increased with plant age. Interestingly, polyphenol production and antiradical activity increased with plant age, too. Salt stress stimulated these two parameters, especially in the less sensitive provenance, Soliman. During the first weeks of salt treatment, M. pulegium responded to the salt-induced oxidative stress by an activation of its enzymatic system then the non-enzymatic system took place.