title: Seed 1-cysteine peroxiredoxin antioxidants are not involved in dormancy, but contribute to inhibition of germination during stress.
abstract: Peroxiredoxins (Prx) are thiol-dependent antioxidants containing one (1-cysteine [-Cys]) or two (2-Cys) conserved Cys residues that protect lipids, enzymes, and DNA against reactive oxygen species. In plants, the 1-Cys Prxs are highly expressed during late seed development, and the expression pattern is dormancy related in mature seeds. We have expressed the Arabidopsis 1-Cys Prx AtPER1 in Escherichia coli and show that this protein has antioxidant activity in vitro and protects E. coli in vivo against the toxic oxidant cumene hydroperoxide. Although some 1-Cys Prxs are targeted to the nucleus, a green fluorescent protein-AtPER1 fusion protein was also localized to the cytoplasm in an onion epidermis subcellular localization assay. It has been proposed that seed Prxs are involved in maintenance of dormancy and/or protect the embryo and aleurone layer surviving desiccation against damage caused by reactive oxygen species. These hypotheses were tested using transgenic Arabidopsis lines overexpressing the barley (Hordeum vulgare) 1-Cys PER1 protein and lines with reduced levels of AtPER1 due to antisensing or RNA interference. We found no correlation between Prx levels and the duration of the after-ripening period required before germination. Thus, Prxs are unlikely to contribute to maintenance of dormancy. RNA interference lines almost devoid of AtPER1 protein developed and germinated normally under standard growth room conditions. However, seeds from lines overexpressing PER1 were less inclined to germinate than wild-type seeds in the presence of NaCl, mannitol, and methyl viologen, suggesting that Prx can sense harsh environmental surroundings and play a part in the inhibition of germination under unfavorable conditions.
authors.affiliation: Division of Cell and Molecular Biology, Department of Biology, University of Oslo, P.O. Box 1031 Blindern, N-0315 Oslo, Norway.
authors.forename: Camilla
authors.initials: C
authors.lastname: Haslekås
authors.forename: Marte K
authors.initials: MK
authors.lastname: Viken
authors.forename: Paul E
authors.initials: PE
authors.lastname: Grini
authors.forename: Vigdis
authors.initials: V
authors.lastname: Nygaard
authors.forename: Silje H
authors.initials: SH
authors.lastname: Nordgard
authors.forename: Trine J
authors.initials: TJ
authors.lastname: Meza
authors.forename: Reidunn B
authors.initials: RB
authors.lastname: Aalen
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D018525:Germination / Q000187:drug effects / Q000235:genetics*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008353:Mannitol / Q000494:pharmacology; D010269:Paraquat / Q000494:pharmacology; D010641:Phenotype; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000235:genetics*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D008164:Luminescent Proteins; C111227:Per1 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D008353:Mannitol; D012965:Sodium Chloride; D010269:Paraquat