Effects of nitric oxide on reducing oxidative stress induced by drought in safflower (Carthamus tinctorius L.)

NO is an important signaling molecule in plants, which mediates growth and developmental processes. Among the different environmental stresses, drought is one of the most important limiting factors for growth and production around the world. In this study the effect of sodium nitroprusside (SNP), as a NO donor on the reduction of drought stress in safflower (Carthamus tinctorius L.) was studied. The effect of the concentrations of SNP (0, 15, and 25µM) and water stress (levels 25, 50, 75and 100% FC (Field capacity)) on shoot fresh weight, shoot dry weight, shoot length, leaf area, relative water content (RWC), catalase (CAT), ascorbate peroxidase (APX) superoxidase activities (SOD) and proline content in leaf and root were studied. When plants had three expanded leaves, were treated by SNP and after 24 hours, exposed to drought. After 7 days, plants again were sprayed by SNP. After 2 weeks plants were harvested to evaluate of growth and physiological parameters. The results showed that drought stress reduced shoot fresh weight, shoot dry weight, shoot length, leaf area, RWC and increased CAT and SOD activities and proline content in leaf and root. Interaction of nitric oxide and drought increased growth parameters, CAT and SOD activities and decreased APX activities and proline content. The results showed that the plants treated with NO are more resistance to drought stress. Keywords: Drought stress, Sodium nitroprusside, Safflower, Nitric oxide