Regulation of amino acid uptake in conifers by exogenous and endogenous nitrogen.
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.
Persson
Jörgen
J
Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden. jorgen.persson@genfys.slu.se
Näsholm
Torgny
T
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
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