title: Comparing 2-[18F]fluoro-2-deoxy-D-glucose and [68Ga]gallium-citrate translocation in Arabidopsis thaliana.
abstract: 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)FDG) is a glucose surrogate commonly used in clinical or animal imaging but rarely in plant imaging to trace glucose metabolism. Recently, (18)FDG has been employed in plant imaging for studying photoassimilate translocation and glycoside biosynthesis. There is growing evidence that (18)FDG could be used as a tracer in plant imaging studies to trace sugar dynamics. However, to confirm this hypothesis, it was necessary to show that the observed (18)FDG distribution in an intact plant is an outcome of the chemical nature of the introduced radiotracer and not of the plant vascular architecture or radiotracer introduction method.
  
  
  METHODS
  In the present work, we fed (18)FDG and [(68)Ga]gallium-citrate ((68)Ga-citrate) solution through mature Arabidopsis thaliana leaf and monitored subsequent radioactivity distribution using positron autoradiography. The possible route of radioactivity translocation was elucidated through stem-girdling experiments. We also employed a bi-functional positron emission tomography/computed tomography (PET/CT) modality to capture (18)FDG radiotracer dynamics in one of the plants in order to assess applicability of PET/CT for 4-D imaging in an intact plant.
  
  
  RESULTS
  Autoradiography results showed that [(18)F] radioactivity accumulated mostly in roots and young growing parts such as the shoot apex, which are known to act as sinks for photoassimilate. [(18)F] radioactivity translocation, in this case, occurred mainly via phloem. PET/CT results corroborated with autoradiography. [(68)Ga] radioactivity, on the other hand, was mainly translocated to neighboring leaves and its translocation occurred via both xylem and phloem.
  
  
  CONCLUSIONS
  The radioactivity distribution pattern and translocation route observed after (18)FDG feeding is markedly different from that of (68)Ga-citrate. [(18)F] radioactivity distribution pattern in an intact plant is found similar to the typical distribution pattern of photoassimilates. Despite its limitations in quantification and resolution, PET/CT could be a useful tool to elucidate in vivo dynamics of [(18)F] radioactivity in intact plants.
authors.affiliation: Mass spectrometry/Proteomics research Group, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany.
authors.forename: Amol
authors.initials: A
authors.lastname: Fatangare
authors.affiliation: Department of Cell and Molecular Biology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstr. 11a, D-07745 Jena, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Gebhardt
authors.affiliation: Department of Cell and Molecular Biology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstr. 11a, D-07745 Jena, Germany; Friedrich-Schiller-University Jena, D-07737 Jena, Germany.
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Saluz
authors.affiliation: Mass spectrometry/Proteomics research Group, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany.
authors.forename: Aleš
authors.initials: A
authors.lastname: Svatoš
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000378:metabolism*; D002951:Citrates / Q000737:chemistry / Q000493:pharmacokinetics*; D019788:Fluorodeoxyglucose F18 / Q000737:chemistry / Q000493:pharmacokinetics*; D005708:Gallium / Q000737:chemistry / Q000493:pharmacokinetics*; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism*; D018547:Plant Stems / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002951:Citrates; D019788:Fluorodeoxyglucose F18; D005708:Gallium; C103850:gallium citrate
keywords: Imaging; PET/CT; Photoassimilate; Plant; Translocation