Fig. 3

Responses of endogenous nitric oxide (NO) concentrations and oxidative damage to NO donor (SNP) or NO scavenger (c-PTIO) in root apices under the non-water stress (Con) or water stress conditions. (a) Photographs of NO production after SNP application. Bar = 300 μm. (b) NO production expressed as relative fluorescence. Rice seedlings were either untreated or treated with SNP under water stress. After 3 h and 24 h of treatment, root tips were loaded with 10 μM DAF-FM DA and NO fluorescence was imaged after 20 min using a fluorescence microscope. Endogenous NO concentrations in root are displayed. The lipid peroxidation (c) and carbonyl concentration (d) in rice roots represent the oxidative damage. In the c-PTIO and PEG + c-PTIO treatments, the rice seedlings were pretreated with NO scavenger (c-PTIO) for 3 h followed by non-water stress or water stress. After 3 h, the contents of MDA representing lipid peroxidation and carbonyl group in rice seedling roots were determined. Values represent means ± standard error (SE) (n = 6). Different letters indicate significant differences at P < 0.05. Con indicates control treatment for each N nutrition, i.e., plants receiving non-water stress. FW: fresh weight; TBARS: thiobarbituric acid reactive substances