Fig. 2

Time-dependent endogenous nitric oxide (NO) production and histochemical detection of oxidative damage in the root apices of NH₄⁺- and NO₃⁻-supplied rice seedlings under water stress. (a) Detection of NO fluorescence using DAF-FM DA staining and a fluorescence microscope. NO generation is indicated by green fluorescence. Bar = 300 μm. (b) NO production is expressed as relative fluorescence. To detect the NO production time course, seedling roots exposed to 10% PEG were collected at 0, 3, 6, 12, 24, and 48 h. (c) and (d) Histochemical detection of the aldehydes derived from lipid peroxidation and Evans blue uptake in root apices of rice seedlings under water stress. Rice seedlings were either untreated or subjected to 3 or 24 h of water stress, respectively. Roots were stained with Schiff’s reagent (c) and Evans blue (d), and then immediately photographed under a Leica S6E stereomicroscope (Leica, Solms, Germany). Red/purple indicates the presence of lipid peroxidation detected with Schiff’s reagent. Bar = 1 mm. Endogenous NO concentrations and histochemical detection of oxidative damage in the root are given. In Fig. 2b, the red dotted oval represents the high endogenous NO production in the NH₄⁺- and NO₃⁻-supplied rice, respectively. Values represent means ± standard error (SE) (n = 6). Different letters refer to significant differences at P < 0.05. Con indicates control treatment for each N nutrition, i.e., plants receiving non-water stress