An oxidative burst of hydrogen peroxide during rehydration following desiccation in the moss Atrichum androgynum

Summary The Afromontane understorey moss Atrichum androgynum is shown here to display an oxidative burst of hydrogen peroxide (H 2O2) during rehydration following desiccation. Maximum rates of H 2O2 production, assayed spectrophotometrically using the xylenol orange assay, occurred during the first 15 min of rehydration. Although the production of H2O2 increased with increasing desiccation times, the moss produced significant amounts of H2O2 during rehydration after desiccation for times that did not inhibit photosynthesis or cause potassium (K+) leakage. Atrichum androgynum also produces H2O2 during desiccation; artificially induced desiccation, using polyethylene glycol, strongly stimulates H2O2 production. Experiments involving inhibitors and exogenously supplied reductants indicated that peroxidases might be responsible for the production of H 2O2. Factors that influence the rate of H2O2 production during rehydration included light and the hormone abscisic acid. Patterns of H2O2 production in A. androgynum are discussed in terms of their possible role in defence against pathogenic fungi and bacteria.