ABSTRACT
To better understand the role of salicylic acid (SA) in salt stressed conditions, we analyzed the capacity of the antioxidative defense system and several physiological parameters of the tomato plant Solanum lycopersicum var. Golden Sunrise grown in a hydroponic medium. Our results showed that the addition of SA in the NaCl-enriched medium attenuates the depressive effect of salinity. The decrease in dry weight production in the presence of salt was associated with a reduction in K+ content and a high accumulation of Na+ and Cl- contents in the different organs of tomato. However, exogenous application of SA combined to NaCl induces an ameliorative effect on growth and nutrition parameters. An accumulation of osmoregulatory compounds (proline, proteins) was also detected after SA treatment. The activity of superoxide dismutase (SOD) after native polyacrylamide gel electrophoresis (PAGE) showed that salt stimulates the activity of SOD, both in the presence and absence of SA, in shoots as well as in roots. The gel also revealed a new isoenzyme stimulated by SA in shoots. The revelation of the activity of the guaiacol peroxidase (POX) in the roots and the shoots showed that 4 isoforms were detected in all treatments. Our study suggests that the mechanisms for SA-enhanced salt resistance could be attributed to the higher antioxidant defense activity and the lower accumulation of toxic ions in tomato plants.
