Superoxide dismutase isozyme activity and antioxidant responses of hydroponically cultured Lepidium sativum L. to NaCl stress

摘要

The present study was focused to assess the physiological behavior and antioxidant responses of the medicinal plant Lepidium sativum L. (commonly called Garden cress) subjected hydroponically to NaCl stress during its vegetative growth stage. The results showed that the addition of NaCl to growth medium significantly reduced plant growth. The magnitude of the response was also linked to the plant organ considered and NaCl concentration supplemented to the medium. Tissue hydration seemed unaffected by salinity. Reduction in dry weight (DW) production was associated with a high accumulation of Na+ and Cl- and a significant reduction of K+ content in shoots. The accumulation of osmoregulatory compounds (proline and total sugars) in shoots and roots was greatly increased by NaCl. Activity staining of antioxidants after a native polyacrylamide gel electrophores (PAGE) showed four superoxide dismutase (SOD) isozymes in the extract of leaf-soluble proteins (one Mn-SOD, two Fe-SODs, and one CuZn-SOD), and three isoforms in roots (Mn-SOD, Fe-SOD, and CuZn-SOD). Four peroxidase (POD) isozymes in the roots and only one isozyme in the leaves were detected. The work demonstrated that activities of antioxidant defense enzymes changed in parallel with the increased salinity. In summary, these findings proved that L. sativum can be classified as a moderately tolerant plant to salinity. © 2013 Taylor & Francis.