title: Regulation of peroxiredoxin expression versus expression of Halliwell-Asada-Cycle enzymes during early seedling development of Arabidopsis thaliana.
abstract: During early seedling development of oil seed plants, the transition from lipid based heterotrophic to photoautotrophic carbohydrate metabolism is accompanied with a biphasic control of the chloroplast antioxidant system. In continuous light, organellar peroxiredoxins (Prx) and thylakoid-bound ascorbate peroxidase (tAPx) are activated early in seedling development, while stromal ascorbate peroxidase (sAPx), Cu/Zn-superoxide dismutase-2 (Csd2) and monodehydroascorbate reductase (MDHAR) and the cytosolic peroxiredoxins PrxIIB, PrxIIC and PrxIID are fully activated between 2.5 and 3 days after radicle emergence (DARE). Discontinuous light synchronized the expression of chloroplast antioxidant enzymes, but defined diurnally specific typeII-Prx-patterns in the cytosol and initiated chloroplast senescence around 2.5 DARE. Carbohydrate feeding uncoupled sAPx expression from the light pattern. In contrast, sucrose-feeding did not significantly impact on Prx transcript amounts. It is concluded that upon post-germination growth Prxs are activated endogenously to provide early antioxidant protection, which is supported by the Halliwell-Asada-Cycle, whose expressional activation depends on metabolic signals provided only later in development or in day-night-cycles.
authors.affiliation: Biochemistry and Physiology of Plants, W5, Bielefeld University, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pena-Ahumada
authors.forename: Uwe
authors.initials: U
authors.lastname: Kahmann
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Dietz
authors.forename: Margarete
authors.initials: M
authors.lastname: Baier
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D060387:Ascorbate Peroxidases; D050260:Carbohydrate Metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure; D005453:Fluorescence; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007522:Isocitrate Lyase / Q000378:metabolism; D008027:Light; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D054464:Peroxiredoxins; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D036226:Seedlings / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000975:Antioxidants; D002734:Chlorophyll; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D054464:Peroxiredoxins; D007522:Isocitrate Lyase; D000077194:Chlorophyll A