title: Why are literature data for H2O2 contents so variable? A discussion of potential difficulties in the quantitative assay of leaf extracts.
abstract: Leaf metabolism produces H2O2 at high rates, but current concepts suggest that the potent signalling effects of this oxidant require that concentrations be controlled by a battery of antioxidative enzymes. The extent to which H2O2 is allowed to accumulate remains unclear. There is little consensus on leaf H2O2 values in the literature and measured concentrations in unstressed conditions range from 50-5000 nmol g(-1) fresh weight, a difference that probably reflects technical inaccuracies as much as biological variability. This article uses new experimental and literature data to examine some of the difficulties in accurately measuring H2O2 in leaf extracts. Potential problems relate to sensitivity, interference from other redox-active compounds, and H2O2 stability during sample preparation. Particular attention is drawn to the influence of tissue mass/extraction volume in the quantitative estimation of H2O2 contents, and the possibility that this factor could contribute to the variability of literature data.
authors.affiliation: Institut de Biotechnologie des Plantes, UMR CMRS 8618, Université de Paris sud XI, F-91405 Orsay Cedex, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Queval
authors.forename: Jutta
authors.initials: J
authors.lastname: Hager
authors.forename: Bertrand
authors.initials: B
authors.lastname: Gakière
authors.forename: Graham
authors.initials: G
authors.lastname: Noctor
mesh_terms: D000222:Adaptation, Physiological; D001205:Ascorbic Acid / Q000737:chemistry; D002736:Chloroplasts / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D010100:Oxygen / Q000737:chemistry; D010636:Phenols; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013454:Sulfoxides; D014992:Xylenes / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D010636:Phenols; D010936:Plant Extracts; D013454:Sulfoxides; D014992:Xylenes; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid; C016833:xylenol orange; D010100:Oxygen