title: Linking chloroplast antioxidant defense to carbohydrate availability: the transcript abundance of stromal ascorbate peroxidase is sugar-controlled via ascorbate biosynthesis.
abstract: All genes encoding chloroplast antioxidant enzymes are nuclear-encoded and posttranscriptionally targeted to chloroplasts. The transcript levels of most of them decreased upon sucrose feeding like the transcript levels of many genes encoding components of the photosynthetic electron transport chain. However, the transcript abundance of stromal ascorbate peroxidase (s-APX; At4g08390) increased. Due to mild sugar application conditions, the plants kept the phosphorylation status of the ADP+ATP pool and the redox states of the NADPH+NADP+ and the ascorbate pools under control, which excludes them as signals in s-APX regulation. Correlation with ascorbate pool size regulation and comparison of transcript abundance regulation in the starch-biosynthetic mutant adg1, the ascorbate biosynthesis mutant vtc1, and the abscisic acid (ABA) biosynthetic mutant aba2 showed a link between sugar induction of s-APX and ascorbate biosynthesis.
authors.affiliation: a Former address: Plant Physiology and Biochemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Heiber
authors.forename: Wenguo
authors.initials: W
authors.lastname: Cai
authors.forename: Margarete
authors.initials: M
authors.lastname: Baier
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis; D000872:Anthocyanins / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D060387:Ascorbate Peroxidases / Q000235:genetics*; D001205:Ascorbic Acid / Q000096:biosynthesis*; D050260:Carbohydrate Metabolism / Q000187:drug effects / Q000528:radiation effects; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D009154:Mutation; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013213:Starch / Q000096:biosynthesis; D013395:Sucrose / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D012333:RNA, Messenger; D013395:Sucrose; D000040:Abscisic Acid; D013213:Starch; D060387:Ascorbate Peroxidases; D001205:Ascorbic Acid
keywords: antioxidant; ascorbate; carbohydrate; chloroplast; gene expression; stromal ascorbate peroxidase.