title: Apoplastic ascorbate metabolism and its role in the regulation of cell signalling.
abstract: The apoplast has crucial functions in plant biology. It comprises all the compartments beyond the plasmalemma, including the cell wall. As the reservoir of information on the biotic and abiotic environment surrounding the cell and a major conduit of information between cells, the apoplast has functions in stress perception and the subsequent appropriate control of growth and defence. The oxidative burst phenomenon, caused by environmental challenges and pathogen attack in particular, oxidises the apoplast. Ascorbic acid (AA), the major and probably the only antioxidant buffer in the apoplast, becomes oxidised in these conditions. The apoplastic enzyme ascorbate oxidase (AO) also regulates the reduction/oxidation (redox) state of the apoplastic ascorbate pool. We propose that a key function of the oxidative burst and of AO is to modify the apoplastic redox state in such a way as to modify receptor activity and signal transduction to regulate defence and growth.
authors.affiliation: Crop Performance and Improvement Division, Rothamsted Research, Harpenden, AL5 2JQ, Hertfordshire, UK.
authors.forename: Cristina
authors.initials: C
authors.lastname: Pignocchi
authors.forename: Christine H
authors.initials: CH
authors.lastname: Foyer
mesh_terms: D001204:Ascorbate Oxidase / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D063245:Plant Development; D010944:Plants / Q000201:enzymology / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D001204:Ascorbate Oxidase; D001205:Ascorbic Acid