title: Cereal grain, rachis and pulse seed amino acid δ15N values as indicators of plant nitrogen metabolism.
abstract: Natural abundance δ(15)N values of plant tissue amino acids (AAs) reflect the cycling of N into and within plants, providing an opportunity to better understand environmental and anthropogenic effects on plant metabolism. In this study, the AA δ(15)N values of barley (Hordeum vulgare) and bread wheat (Triticum aestivum) grains and rachis and broad bean (Vicia faba) and pea (Pisum sativum) seeds, grown at the experimental farm stations of Rothamsted, UK and Bad Lauchstädt, Germany, were determined by GC-C-IRMS. It was found that the δ(15)N values of cereal grain and rachis AAs could be largely attributed to metabolic pathways involved in their biosynthesis and catabolism. The relative (15)N-enrichment of phenylalanine can be attributed to its involvement in the phenylpropanoid pathway and glutamate has a δ(15)N value which is an average of the other AAs due to its central role in AA-N cycling. The relative AA δ(15)N values of broad bean and pea seeds were very different from one another, providing evidence for differences in the metabolic routing of AAs to the developing seeds in these leguminous plants. This study has shown that AA δ(15)N values relate to known AA biosynthetic pathways in plants and thus have the potential to aid understanding of how various external factors, such as source of assimilated N, influence metabolic cycling of N within plants.
authors.affiliation: Organic Geochemistry Unit, Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Bristol, UK.
authors.forename: Amy K
authors.initials: AK
authors.lastname: Styring
authors.affiliation: School of Archaeology, University of Oxford, 36 Beaumont Street, Oxford, UK.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Fraser
authors.affiliation: School of Archaeology, University of Oxford, 36 Beaumont Street, Oxford, UK.
authors.forename: Amy
authors.initials: A
authors.lastname: Bogaard
authors.affiliation: Organic Geochemistry Unit, Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Bristol, UK. Electronic address: R.P.Evershed@bristol.ac.uk.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Evershed
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D002523:Edible Grain / Q000737:chemistry* / Q000201:enzymology; D001467:Hordeum / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis* / Q000378:metabolism; D018532:Pisum sativum / Q000378:metabolism; D012639:Seeds / Q000737:chemistry* / Q000201:enzymology; D014908:Triticum / Q000378:metabolism; D031307:Vicia faba / Q000378:metabolism
chemical_list: D000596:Amino Acids; D009584:Nitrogen
keywords: Amino acids; Hordeum vulgare; Nitrogen; Pisum sativum; Triticum aestivum; Vicia faba; δ(15)N values