title: Real time visualization of 13N-translocation in rice under different environmental conditions using positron emitting Ttacer imaging system.
abstract: The ammonium ion is an indispensable nitrogen source for crops, especially paddy rice (Oryza sativa L. cv Nipponbare). Until now, it has been impossible to measure ammonium uptake and nitrogen movement in plants in real time. Using the new technologies of PETIS (positron emitting tracer imaging system) and PMPS (positron multi-probe system), we were able to visualize the real time translocation of nitrogen and water in rice plants. We used positron-emitting 13N-labeled ammonium (13NH4+) and 15O-water to monitor the movement. In plants cultured under normal conditions, 13NH4+ supplied to roots was taken up, and a 13N signal was detected at the discrimination center, the basal part of the shoots, within 2 minutes. This rapid translocation of (13)N was almost completely inhibited by a glutamine synthetase inhibitor, methionine sulfoximine. In general, nitrogen deficiency enhanced 13N translocation to the discrimination center. In the dark, 13N translocation to the discrimination center was suppressed to 40% of control levels, whereas 15O-water flow from the root to the discrimination center stopped completely in the dark. In abscisic acid-treated rice, 13N translocation to the discrimination center was doubled, whereas translocation to leaves decreased to 40% of control levels. Pretreatment with NO3- for 36 hours increased 13N translocation from the roots to the discrimination center to 5 times of control levels. These results suggest that ammonium assimilation (from the roots to the discrimination center) depends passively on water flow, but actively on NH4+-transporter(s) or glutamine synthetase(s).
authors: Department of Applied Biological Chemistry, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: S
authors: S
authors: Kiyomiya
authors: H
authors: H
authors: Nakanishi
authors: H
authors: H
authors: Uchida
authors: A
authors: A
authors: Tsuji
authors: S
authors: S
authors: Nishiyama
authors: M
authors: M
authors: Futatsubashi
authors: H
authors: H
authors: Tsukada
authors: N S
authors: NS
authors: Ishioka
authors: S
authors: S
authors: Watanabe
authors: T
authors: T
authors: Ito
authors: C
authors: C
authors: Mizuniwa
authors: A
authors: A
authors: Osa
authors: S
authors: S
authors: Matsuhashi
authors: S
authors: S
authors: Hashimoto
authors: T
authors: T
authors: Sekine
authors: S
authors: S
authors: Mori
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D003624:Darkness; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors; D007700:Kinetics; D008717:Methionine Sulfoximine / Q000494:pharmacology; D009590:Nitrogen Radioisotopes / Q000493:pharmacokinetics*; D012275:Oryza / Q000502:physiology*; D010104:Oxygen Radioisotopes / Q000493:pharmacokinetics; D018515:Plant Leaves / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D009590:Nitrogen Radioisotopes; D010104:Oxygen Radioisotopes; D000644:Quaternary Ammonium Compounds; D014867:Water; D008717:Methionine Sulfoximine; D005974:Glutamate-Ammonia Ligase