title: Regulation of amino acid uptake in conifers by exogenous and endogenous nitrogen.
abstract: Although an accumulating amount of research clearly indicates that plants are capable of taking up exogenous amino acids, the actual importance of such organic N sources for plant N nutrition is under debate. In this study, we show that amino acid uptake by Scots pine (Pinus sylvestris L.) is significantly decreased by elevated internal NH(4)(+) levels, while it increases following exposure to exogenous amino acids. Furthermore, amino acid uptake is larger in N-deficient plants than in plants grown with a large access of N. The regulatory pattern of amino acid uptake shows important similarities to the regulation of NO(3)(-) and NH(4)(+) transport as well as to the regulation of yeast amino acid transporters. In addition, our data suggest that uptake may be regulated by factors not originating from N metabolism. The up-regulation of uptake in response to N deficiency suggests that amino acid uptake may be a significant contributor to the N economy of P. sylvestris.
authors.affiliation: Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden. jorgen.persson@genfys.slu.se
authors.forename: Jörgen
authors.initials: J
authors.lastname: Persson
authors.forename: Torgny
authors.initials: T
authors.lastname: Näsholm
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000596:Amino Acids / Q000378:metabolism* / Q000494:pharmacology; D000625:Aminooxyacetic Acid / Q000494:pharmacology; D001377:Azaserine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005970:Glutamate Synthase / Q000037:antagonists & inhibitors; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology; D005973:Glutamine / Q000378:metabolism / Q000494:pharmacology; D008717:Methionine Sulfoximine / Q000494:pharmacology; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000037:antagonists & inhibitors; D009566:Nitrates / Q000378:metabolism / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology*; D018517:Plant Roots / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism / Q000494:pharmacology; D064028:Tracheophyta / Q000378:metabolism*; D000637:Transaminases / Q000037:antagonists & inhibitors; D017973:Tungsten Compounds / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D000596:Amino Acids; D004791:Enzyme Inhibitors; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D017973:Tungsten Compounds; D005973:Glutamine; D000625:Aminooxyacetic Acid; D008717:Methionine Sulfoximine; D018698:Glutamic Acid; D001377:Azaserine; D005970:Glutamate Synthase; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D000637:Transaminases; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen; C045951:tungstate