title: Peering into the separate roles of root and shoot cytosolic glutamine synthetase 1;2 by use of grafting experiments in Arabidopsis.
abstract: Cytosolic glutamine synthetase 1;2 plays an important role in the primary nitrogen assimilation in roots. Based on characterization of the knockout mutant gln1;2 we have recently demonstrated that Gln1;2 is also essential for ammonium handling in shoots. Here we built reciprocally grafted plants between wild type (Wt) and gln1;2 in order to separate the root and shoot roles of Gln1;2. Significant reduction in silique number and seed yield were observed in the grafted plants 1;2shoot/Wtrootrelative to Wtshoot/1;2rootand Wtshoot/Wtroot. Shoot Gln1;2 thus played a crucial role for seed production. Tracing experiments with15N showed that the relative nitrogen remobilization from vegetative organs to seeds in gln1;2 was just as efficient as in the Wt plants. This was the case although the total quantity of nitrogen in gln1;2 was significantly lower compared to that in the Wt. We conclude that the functions of shoot Gln1;2 are primarily associated with internal N signaling for establishment of seed yield capacity rather than with nitrogen remobilization.
authors.affiliation: a Department of Plant and Environment Sciences & Copenhagen Plant Science Center , Faculty of Science, University of Copenhagen , Thorvaldsensvej , Frederiksberg C , Denmark.|b Laboratory of In Vitro Diagnostic Technology, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences , China.
authors.forename: Miao
authors.initials: M
authors.lastname: Guan
authors.affiliation: a Department of Plant and Environment Sciences & Copenhagen Plant Science Center , Faculty of Science, University of Copenhagen , Thorvaldsensvej , Frederiksberg C , Denmark.
authors.forename: Jan K
authors.initials: JK
authors.lastname: Schjoerring
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology*; D018506:Gene Expression Regulation, Plant; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology* / Q000378:metabolism*; D018520:Plant Shoots / Q000201:enzymology* / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology / Q000378:metabolism
chemical_list: D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen
keywords: Arabidopsis; cytosolic glutamine synthetase; grafting; mutant; nitrogen; seed productivity; signaling