Central role of salicylic acid in resistance of safflower (Carthamus tinctorius L.) against salinity

The effects of salicylic acid (SA) on growth parameters and enzyme activities were investigated in salt-stressed safflower (Carthamus tinctorius L.). Twenty-five days after sowing, seedlings were treated with NaCl (0, 100, and 200 mM) and SA (1 mM), and were harvested at 21 days after treatments. Results showed that some growth parameters decreased under salinity, while malondialdehyde (MDA) and hydrogen peroxide (H2O2) content, phenolic compounds, and some enzyme activities increased. SA application increased some growth parameters, MDA and H2O2 content, and enzyme activities except catalase (CAT), which was different from the other enzymes and SA significantly reduced CAT activity in plants. These results suggest that SA-induced tolerance to salinity may be related to regulation of antioxidative responses and H2O2 level. Our study suggested that the resistant safflower can direct reactive oxygen species from a threat to an opportunity by using SA. Therefore, exogenous application of SA played this role through regulation of the antioxidant system