title: Visualization of Uptake of Mineral Elements and the Dynamics of Photosynthates in Arabidopsis by a Newly Developed Real-Time Radioisotope Imaging System (RRIS).
abstract: Minerals and photosynthates are essential for many plant processes, but their imaging in live plants is difficult. We have developed a method for their live imaging in Arabidopsis using a real-time radioisotope imaging system. When each radioisotope,(22)Na,(28)Mg,(32)P-phosphate,(35)S-sulfate,(42)K,(45)Ca,(54)Mn and(137)Cs, was employed as an ion tracer, ion movement from root to shoot over 24 h was clearly observed. The movements of(22)Na,(42)K,(32)P,(35)S and(137)Cs were fast so that they spread to the tip of stems. In contrast, high accumulation of(28)Mg,(45)Ca and(54)Mn was found in the basal part of the main stem. Based on this time-course analysis, the velocity of ion movement in the main stem was calculated, and found to be fastest for S and K among the ions we tested in this study. Furthermore, application of a heat-girdling treatment allowed determination of individual ion movement via xylem flow alone, excluding phloem flow, within the main stem of 43-day-old Arabidopsis inflorescences. We also successfully developed a new system for visualizing photosynthates using labeled carbon dioxide,(14)CO2 Using this system, the switching of source/sink organs and phloem flow direction could be monitored in parts of whole shoots and over time. In roots,(14)C photosynthates accumulated intensively in the growing root tip area, 200-800 µm behind the meristem. These results show that this real-time radioisotope imaging system allows visualization of many nuclides over a long time-course and thus constitutes a powerful tool for the analysis of various physiological phenomena.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Sugita
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan.
authors.forename: Natsuko I
authors.initials: NI
authors.lastname: Kobayashi
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirose
authors.affiliation: AgroSolutions Division-Japan, Sumitomo Chemical Co., Ltd., 4-6-1, Ichibancho, Aoba-ku Sendai, Miyagi, 980-0811 Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Saito
authors.affiliation: Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 Japan.
authors.forename: Ren
authors.initials: R
authors.lastname: Iwata
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012 Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Tanoi
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan atomoko@mail.ecc.u-tokyo.ac.jp.
authors.forename: Tomoko M
authors.initials: TM
authors.lastname: Nakanishi
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D002245:Carbon Dioxide / Q000737:chemistry; D002250:Carbon Radioisotopes; D008670:Metals / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics; D008903:Minerals / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics*; D052585:Phloem / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D011877:Radionuclide Imaging / Q000379:methods*; D052584:Xylem / Q000502:physiology
chemical_list: D002250:Carbon Radioisotopes; D008670:Metals; D008903:Minerals; D002245:Carbon Dioxide
keywords: Arabidopsis; Live imaging; Mineral elements; Photosynthates; Real-time radioisotope imaging system; Sink–source switching