Physiological and antioxidant responses of Mentha pulegium (Pennyroyal) to salt stress

Abstract

Mentha pulegium L. is a medicinal and aromatic plant belonging to the Labiatae family present in the humid to the arid bioclimatic regions of Tunisia. We studied the effect of different salt concentrations on plant growth, mineral composition and antioxidant responses. Physiological and biochemical parameters were assessed in the plant organs after 2 weeks of salt treatment with 25, 50, 75 and 100 mM NaCl. Results showed that, growth was reduced even by 25 mM, and salt effect was more pronounced in shoots (leaves and stems) than in roots. This growth decrease was accompanied by a restriction in tissue hydration and K ? uptake, as well as an increase in Na ? levels in all organs. Considering the response of antioxidant enzymes to salt, leaves and roots reacted differently to saline conditions. Leaf and root guaiacol peroxidase activity showed an increase by different concentration of NaCl, but superoxide dismutase activity in the same organs showed a slight modification in NaCl-treated leaves and roots. Moreover, polyphenol contents and antioxidant activity were analysed in M. pulegium leaves and roots under salt constraint. The analysis showed an increase of total polyphenol content (2.41-8.17 mg gallic acid equivalent g -1 dry weight) in leaves. However, methanol extract of leaves at 100 mM NaCl displayed the highest DPPHÁ scavenging ability with the lowest IC 50 value (0.27 lg ml -1 ) in comparison with control which exhibited IC 50 equal to 0.79 lg ml -1 .

Changes in antioxidant enzymes activities and proline, total phenol and anthocyanine contents inHyssopus officinalisL. plants under salt stress

“…Similar results were reported in Nigella sativa showing that the phenolic contents were also affected significantly due to salt stress [7]. Queslati et al [31] demonstrated the increase of phenols following saline treatment of Mentha pulegium. Salinity stress-induced total phenolic content accumulation has also been previously observed in strawberry and sugarcane [14].…”

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

“…Hence, the salt stimulating effect in Soliman could explain the maintenance of plant vigor up to 6 weeks of salt treatment. Our results are in agreement with those of Oueslati et al (2010) who found an increase in total polyphenols and antiradical activities in a different Tunisian provenance (Nefza) of the same species. Navaro et al (2006) also demonstrated that total phenolic concentration increased with salinity level in red pepper fruits.…”

“…These results are in agreement with those of Oueslati et al (2010) who found that the whole plant dry weight of this species was reduced by 46, 59, and 58%, respecttively at 25, 50 and 75 mM NaCl. Nevertheless, intraspecific variability in salt-induced responses was revealed in our study.…”

“…Mentha pulegium L. is one of these AMPs and was described as a potential source of phenolic compounds (Stycharz and Shetty, 2002;. Under salt treatment, it showed an increase in polyphenol concentration and an amelioration of enzymatic and non-enzymatic antioxidant properties (Oueslati et al, 2010). The aim of the present work was to study the effects of salinity on antioxidant properties in two Tunisian provenances of M. pulegium differing in their salt tolerance.…”

Effect of Nacl and Phenylalanine on the Production of some Secondary Metabolites in In Vitro Cultures of Mentha longifolia

“…Also, Cik et al (2009) found that accumulation of phenolic acids (protocatechuic, chlorogenic and caffeic acids) on Matricaria chamomilla increased by salinity. Bourgou et al (2010) showed increase of phenols with saline treatment on Nigella sativa and Queslati et al (2010) on Mentha pulegium.…”