title: Amino acid uptake by temperate tree species characteristic of low- and high-fertility habitats.
abstract: The relationship between inorganic nitrogen (N) cycling and plant productivity is well established. However, recent research has demonstrated the ability of plants to take up low molecular weight organic N compounds (i.e., amino acids) at rates that often rival those of inorganic N forms. In this study, we hypothesize that temperate forest tree species characteristic of low-fertility habitats will prefer amino acids over species characteristic of high-fertility habitats. We measured the uptake of (15)N-labeled amino acids (glycine, glutamine, arginine, serine), ammonium (NH(4)(+)), and nitrate (NO(3)(-)) by four tree species that commonly occur in eastern North America, where their abundances have been correlated with inorganic N availability. Specific uptake rates of amino acids were largely similar for all tree species; however, high-fertility species took up NH(4)(+) at rates more than double those of low-fertility species, rendering amino acid N relatively more important to the N nutrition of low-fertility species. Low-fertility species acquired over four times more total N from arginine compared to NH(4)(+) and NO(3)(-); high-fertility species acquired the most N from NH(4)(+). Arginine had the highest uptake rates of any amino acid by all species; there were no significant differences in uptake rates of the remaining amino acids. Our results support the idea that the dominant species in a particular habitat are those best able to utilize the most available N resources.
authors.affiliation: Department of Forestry, Michigan State University, East Lansing, MI 48824, USA. scottemi@msu.edu
authors.forename: Emily E
authors.initials: EE
authors.lastname: Scott
authors.forename: David E
authors.initials: DE
authors.lastname: Rothstein
mesh_terms: D000596:Amino Acids / Q000378:metabolism / Q000493:pharmacokinetics*; D017753:Ecosystem; D029962:Fagaceae / Q000502:physiology*; D031661:Fraxinus / Q000502:physiology*; D007553:Isotope Labeling; D009566:Nitrates / Q000032:analysis / Q000493:pharmacokinetics; D009584:Nitrogen / Q000032:analysis / Q000493:pharmacokinetics; D009587:Nitrogen Isotopes / Q000032:analysis / Q000493:pharmacokinetics; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D027861:Prunus / Q000502:physiology*; D000644:Quaternary Ammonium Compounds / Q000032:analysis / Q000493:pharmacokinetics; D012987:Soil / Q000737:chemistry; D013045:Species Specificity; D014197:Trees / Q000502:physiology
chemical_list: D000596:Amino Acids; D009566:Nitrates; D009587:Nitrogen Isotopes; D000644:Quaternary Ammonium Compounds; D012987:Soil; D009584:Nitrogen