Figure 5.
Transient accumulation of H2O2 in isolated protoplasts from S44, M44 and M81 after exposure to 500 µmol quanta m−2 s−1 at 10°C for a given time. (a) Typical EPR spectra of the 4-POBN/α-hydroxyethyl adduct recorded at 0, 10, 30, 60 min after illumination obtained in protoplasts of S44. The size of the signal indicates the concentration of H2O2 indirectly by the trapping of hydroxyl radicals (•OH). •OH radicals were generated from H2O2 in a Fe2+-catalysed Fenton reaction. (b) Average amplitude of the EPR signals ± s.e. (closed squares, S44; open squares, M44; open triangles, M81). Data are mean ± s.e. of four to five measurements. The significance level (*p < 0.05) is indicated.