title: Increased glutamine in leaves of poplar transgenic with pine GS1a caused greater anthranilate synthetase α-subunit (ASA1) transcript and protein abundances: an auxin-related mechanism for enhanced growth in GS transgenics?
abstract: The initial reaction in the pathway leading to the production of indole-3-acetic acid (IAA) in plants is the reaction between chorismate and glutamine to produce anthranilate, catalysed by the enzyme anthranilate synthase (ASA; EC 4.1.3.27). Compared with non-transgenic controls, leaves of transgenic poplar with ectopic expression of the pine cytosolic glutamine synthetase (GS1a; EC 6.3.1.2) produced significantly greater glutamine and significantly enhanced ASA α-subunit (ASA1) transcript and protein (approximately 130% and 120% higher than in the untransformed controls, respectively). Similarly, tobacco leaves fed with 30 mM glutamine and 2 mM chorismate showed enhanced ASA1 transcript and protein (175% and 90% higher than controls, respectively). Furthermore, free IAA was significantly elevated both in leaves of GS1a transgenic poplar and in tobacco leaves fed with 30 mM glutamine and 2 mM chorismate. These results indicated that enhanced cellular glutamine may account for the enhanced growth in GS transgenic poplars through the regulation of auxin biosynthesis.
authors.affiliation: Department of Biological Sciences, Rutgers University, University Heights, Newark, NJ 07102, USA.
authors.forename: Huimin
authors.initials: H
authors.lastname: Man
authors.forename: Stephan
authors.initials: S
authors.lastname: Pollmann
authors.forename: Elmar W
authors.initials: EW
authors.lastname: Weiler
authors.forename: Edward G
authors.initials: EG
authors.lastname: Kirby
mesh_terms: D000878:Anthranilate Synthase / Q000235:genetics* / Q000378:metabolism; D002827:Chorismic Acid / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism* / Q000494:pharmacology; D015151:Immunoblotting; D007210:Indoleacetic Acids / Q000378:metabolism*; D028223:Pinus / Q000187:drug effects / Q000201:enzymology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D030821:Plants, Genetically Modified; D032107:Populus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D021122:Protein Subunits; D012333:RNA, Messenger; D005973:Glutamine; D000878:Anthranilate Synthase; D005974:Glutamate-Ammonia Ligase; D002827:Chorismic Acid