title: ASN1-encoded asparagine synthetase in floral organs contributes to nitrogen filling in Arabidopsis seeds.
abstract: Despite a general view that asparagine synthetase generates asparagine as an amino acid for long-distance transport of nitrogen to sink organs, its role in nitrogen metabolic pathways in floral organs during seed nitrogen filling has remained undefined. We demonstrate that the onset of pollination in Arabidopsis induces selected genes for asparagine metabolism, namely ASN1 (At3g47340), GLN2 (At5g35630), GLU1 (At5g04140), AapAT2 (At5g19950), ASPGA1 (At5g08100) and ASPGB1 (At3g16150), particularly at the ovule stage (stage 0), accompanied by enhanced asparagine synthetase protein, asparagine and total amino acids. Immunolocalization confined asparagine synthetase to the vascular cells of the silique cell wall and septum, but also to the outer and inner seed integuments, demonstrating the post-phloem transport of asparagine in these cells to developing embryos. In the asn1 mutant, aberrant embryo cell divisions in upper suspensor cell layers from globular to heart stages assign a role for nitrogen in differentiating embryos within the ovary. Induction of asparagine metabolic genes by light/dark and nitrate supports fine shifts of nitrogen metabolic pathways. In transgenic Arabidopsis expressing promoterCaMV35S::ASN1 fusion, marked metabolomics changes at stage 0, including a several-fold increase in free asparagine, are correlated to enhanced seed nitrogen. However, specific promoterNapin2S::ASN1 expression during seed formation and a six-fold increase in asparagine toward the desiccation stage result in wild-type seed nitrogen, underlining that delayed accumulation of asparagine impairs the timing of its use by releasing amide and amino nitrogen. Transcript and metabolite profiles in floral organs match the carbon and nitrogen partitioning to generate energy via the tricarboxylic acid cycle, GABA shunt and phosphorylated serine synthetic pathway.
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Gaufichon
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Marmagne
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Observatoire du Végétal - Cytologie Imagerie, RD10, Versailles, F-78026, France.
authors.forename: Katia
authors.initials: K
authors.lastname: Belcram
authors.affiliation: Department of Applied Biological Chemistry, The University of Tokyo, Yayoi l-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Tadakatsu
authors.initials: T
authors.lastname: Yoneyama
authors.affiliation: Institute for Protein Research, Division of Protein Chemistry, Laboratory of Regulation of Biological Reactions, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Sakakibara
authors.affiliation: Institute for Protein Research, Division of Protein Chemistry, Laboratory of Regulation of Biological Reactions, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Hase
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Observatoire du Végétal - Cytologie Imagerie, RD10, Versailles, F-78026, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Grandjean
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Observatoire du Végétal - Chimie Métabolisme, RD10, Versailles, F-78026, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Observatoire du Végétal - Chimie Métabolisme, RD10, Versailles, F-78026, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Citerne
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Observatoire du Végétal - Chimie Métabolisme, RD10, Versailles, F-78026, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Boutet-Mercey
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Masclaux-Daubresse
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Chardon
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Soulay
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Xiaole
authors.initials: X
authors.lastname: Xu
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Trassaert
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Maryam
authors.initials: M
authors.lastname: Shakiebaei
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Amina
authors.initials: A
authors.lastname: Najihi
authors.affiliation: INRA, IJPB, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, Versailles, F-78026, France.
authors.forename: Akira
authors.initials: A
authors.lastname: Suzuki
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001217:Aspartate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D052585:Phloem / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D029681:Arabidopsis Proteins; D001217:Aspartate-Ammonia Ligase; D009584:Nitrogen
keywords: 
  Arabidopsis thaliana
  ; ASN1 (At3 g47340); amino acids; asparagine synthetase; nitrogen metabolism; phloem transport; reproductive organs; seeds