Salicylic acid and hydrogen peroxide priming as a means to induce salt stress tolerance of wheat

In this study, we investigated the role of salicylic acid (SA) and hydrogen peroxide (H2O2) priming in ameliorating salinity stress on wheat (Triticum aestivum L. cv Mihan) grown under hydroponic culture. Seeds of wheat were primed in distilled water (control), as well as different solutions of salicylic acid (0.1, 0.5 and 1 mM) and/or H2O2 (1, 20 and 200 mM) for 24 h at 25°C. Seven-day-old seedlings were transferred to Hoagland nutrient solution. Experiments were undertaken in complete randomized block design using 4 independent replications. Salinity stress drastically affected the plants as indicated by decreased biomass of shoots (about 25%). However, H2O2 priming at 20 mM raised free radical scavenging activities of wheat leaf, as evaluated by decrease in malondialdehyde (MDA) levels. These results indicated that H2O2 priming could prevent negative effects of salinity stress on the biomass and photosystem performance. While SA priming could not ameliorate the negative effect of salt on wheat seedlings, the use of both SA and H2O2 as priming agents had the most significant alleviating effect against NaCl stress. This ameliorative effect was achieved through stimulation of catalase activity (about 37%) and non-enzymatic (phenols) antioxidants (about 45%) and lowering tissue MDA contents. These results further confirm that the use of both SA and H2O2 as priming agents participated in the protection of membranes against the destabilizing effect of salt stress. Additionally, the use of both SA and H2O2 as priming agents mitigated the negative effects of salinity on the photochemical efficiency of PSII.