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Hydrogen peroxide metabolism and functions in plants

Smirnoff, Nicholas, Arnaud, Dominique
Thenew phytologist 2019 v.221 no.3 pp. 1197-1214
acclimation, aquaporins, ascorbate peroxidase, autophagy, biochemical pathways, catalase, chloroplasts, crosslinking, cysteine, electron transfer, glutathione, hydrogen peroxide, hydroxyl radicals, image analysis, lignification, metabolism, mitochondria, pathogens, peroxiredoxin, phosphotransferases (kinases), physiological transport, plasma membrane, polymers, signal transduction, superoxide anion, superoxide dismutase, toxicity, transcription factors
Contents Summary 1197 I. Introduction 1198 II. Measurement and imaging of H₂O₂ 1198 III. H₂O₂ and O₂·⁻ toxicity 1199 IV. Production of H₂O₂: enzymes and subcellular locations 1200 V. H₂O₂ transport 1205 VI. Control of H₂O₂ concentration: how and where? 1205 VII. Metabolic functions of H₂O₂ 1207 VIII. H₂O₂ signalling 1207 IX. Where next? 1209 Acknowledgements 1209 References 1209 SUMMARY: Hydrogen peroxide (H₂O₂) is produced, via superoxide and superoxide dismutase, by electron transport in chloroplasts and mitochondria, plasma membrane NADPH oxidases, peroxisomal oxidases, type III peroxidases and other apoplastic oxidases. Intracellular transport is facilitated by aquaporins and H₂O₂ is removed by catalase, peroxiredoxin, glutathione peroxidase‐like enzymes and ascorbate peroxidase, all of which have cell compartment‐specific isoforms. Apoplastic H₂O₂ influences cell expansion, development and defence by its involvement in type III peroxidase‐mediated polymer cross‐linking, lignification and, possibly, cell expansion via H₂O₂‐derived hydroxyl radicals. Excess H₂O₂ triggers chloroplast and peroxisome autophagy and programmed cell death. The role of H₂O₂ in signalling, for example during acclimation to stress and pathogen defence, has received much attention, but the signal transduction mechanisms are poorly defined. H₂O₂ oxidizes specific cysteine residues of target proteins to the sulfenic acid form and, similar to other organisms, this modification could initiate thiol‐based redox relays and modify target enzymes, receptor kinases and transcription factors. Quantification of the sources and sinks of H₂O₂ is being improved by the spatial and temporal resolution of genetically encoded H₂O₂ sensors, such as HyPer and roGFP2‐Orp1. These H₂O₂ sensors, combined with the detection of specific proteins modified by H₂O₂, will allow a deeper understanding of its signalling roles.