HYDROGEN-PEROXIDE FORMATION IN CULTURED ROSE CELLS IN RESPONSE TO UV-C RADIATION

Suspension‐cultured rose (Rosa damascena Mill. cv. Gloire de Guilan) cells irradiated with UV‐C (254 nm. 558 J m−2) showed a transient production of H2O2 as measured by chemiluminescence of luminol in the presence of peroxidase (EC 1.1 1.1.7). The peak concentration of H2O2, which occurred at about 60–90 min after irradiation, was 8–9 μM. The time course for the appearance of H2O2 matched that for UV–induced K+ efflux. Treatments that inhibited the UV‐induced efflux of K+, including heat and overnight incubation with cycloheximide and diethylmaleate, also inhibited the appearance of H2O2. The converse was not always true, since catalase (EC 1.11.1.6. and salicylhydroxamic acid, which inhibited luminescence, did not stop K+ efflux. We conclude that H2O2 synthesis depends on K+ efflux. Because H2.O2 in the extracellular space is required for lignin synthesis in many plant tissues, we suggest that the UV–stimulated production of H2O2 is an integral part of a defensive lignin synthesis. Copyright © 1990, Wiley Blackwell. All rights reserved