1. Fig. 1. SA-induced the generation of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(O_{2}^{{\cdot}{-}}\) \end{document} and H₂O₂, and increase in [Ca²⁺]_c in tobacco cell suspension. Typical records from eight replicates, of CLA- (A, D) and luminol-CL (B, E), and aequorin-luminescence (C, F) with 0.5 mM SA (A, B, C) or water as control (D, E, F) are shown. Arrows indicate addition of SA or water. CLA-CL and aequorin-luminescence were measured at pH 5.8, and luminol-CL was measured at pH 7.5. rlu stands for relative luminescence units with signal intensity induced by 0.5 mM SA set to 1 rlu.
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

2. Fig. 7. SA-dependent production of MDA catalysed by HRP
Fig. 7. SA-dependent production of MDA catalysed by HRP. The MDA-producing reaction was carried out by adding 1 mM SA to the reaction mixture containing 25 mM K-phosphate (pH 7.5), 150 units ml⁻¹ HRP, 1 mM H₂O₂ and 1 mM ascorbate. Immediately after the addition of SA, the reaction mixture was sampled in a flat-shaped quartz cell and used for measurements of MDA with ESR. (A) MDA in the reaction mixture containing HRP, H₂O₂, ascorbate and SA (complete), or lacking one of the ingredients were measured. Typical records of MDA spectra from five replicates are shown. The ESR signal of MDA was recorded 45 s after initiation of the reaction. Horizontal scale bar indicates magnetic field (1 mT). (B) Effect of SA concentration on production of MDA. (C) Effect of pH on SA-dependent MDA production.
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

3. Fig. 8. Enhancement of SA-induced increase in [Ca²⁺]_c by the addition of HRP to tobacco cell suspension. Cells were pre-incubated with (•) or without (○) HRP (150 units ml⁻¹) for 2 min prior to addition of SA (0.5 mM). Vertical bars represent SE (n=4).
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

4. Fig. 2. Detection of HO˙ formed in tobacco cell suspension culture by ESR. Formation of HO˙ in tobacco suspension culture was detected with ESR using DMPO as a spin trapping agent. Typical ESR spectra of DMPO-OH from eight replicates are shown (A). Horizontal scale bar indicates magnetic field (1 mT). Relative ESR signal intensities are compared (B). Horizontal bars represent SE (n=8). The tobacco cells were incubated in 400 μl of culture medium containing 500 μM DMPO for 5 min. The indicated chemicals were added to the tobacco cell suspension and the culture medium was collected immediately by filtering the cell suspension through nylon mesh. Collected culture medium was used for measurements of HO˙ formation with ESR. The chemicals used are 5 mM H₂O₂, 1 mM SA, 1 mM 1,10-phenanthroline (o-phen), 1 mM DMTU, and 1 mM 2,2′-bipyridyl (bipy).
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

5. Fig. 3. Inhibition of HO˙ formation by SA
Fig. 3. Inhibition of HO˙ formation by SA. Formation of HO˙ in H₂O₂ solution by addition of 1 mM CuSO₄ or irradiation with UV light, was detected with ESR using DMPO as a spin trapping agent. The reaction mixtures contained 100 mM K-phosphate (pH 7.0), 10 mM H₂O₂, 500 μM DMPO and indicated concentrations of SA. The HO˙-forming reaction was carried out by mixing the reaction mixture with CuSO₄ solution (1 mM) in a total volume of 170 μM in a flat-shaped quartz cell, or by irradiating the quartz cell containing the reaction mixture with UV-light. Immediately after mixing with CuSO₄, or 1 min after UV-irradiation, the quartz cells were set on the ESR instrument for measurements of DMPO-OH.
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

6. Fig. 4. SA-induced MDA production in tobacco suspension culture
Fig. 4. SA-induced MDA production in tobacco suspension culture. Typical ESR spectra of MDA from five replicates were shown. The cell suspension culture was treated with 10 mM SA or 10 mM H₂O₂. The culture medium was sampled immediately after addition of SA by filtering the cell suspension through nylon mesh. Collected culture medium was used for measurements of HO˙ formation with ESR within 90 s after addition of SA or H₂O₂. Horizontal scale bar indicates magnetic field (1 mT).
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

7. Fig. 5. Effects of ascorbate, CuZn-SOD and SHAM on the SA-induced production of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(O_{2}^{{\cdot}{-}}\) \end{document}, H₂O₂ and MDA, and the increase in [Ca²⁺]_c in the tobacco suspension culture. After addition of SA (0.5 mM), the production of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(O_{2}^{{\cdot}{-}}\) \end{document}, H₂O₂ and MDA, and the increase in [Ca²⁺]_c were measured in the presence or absence of 1 mM ascorbate (AsA), 150 units ml⁻¹ CuZn-SOD (SOD) or 5 mM SHAM. Relative intensities of luminescence and relative MDA signal intensity induced by 0.5 mM SA alone were set to 1.0, respectively. Horizontal bars represent SE (n=6).
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

8. Fig. 6. SA-dependent production of AOS in the HRP model reaction mixture. After addition of 0.5 mM SA or water to HRP, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(O_{2}^{{\cdot}{-}}\) \end{document} and H₂O₂ were measured in the presence or absence of 0.1 μM H₂O₂. The basal reaction mixture contained 25 mM K-phosphate (pH 7.5) and 150 units ml⁻¹ HRP.
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press

9. Fig. 9. A model for mechanism of SA action in tobacco cell suspension culture.
From: Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco cell suspension culture
J Exp Bot. 2000;51(345): doi: /jexbot/
J Exp Bot | © Oxford University Press