title: Transport and compartmentation of phosphite in higher plant cells--kinetic and P nuclear magnetic resonance studies.
abstract: Phosphite (Phi, H(2)PO(3)(-)), being the active part of several fungicides, has been shown to influence not only the fungal metabolism but also the development of phosphate-deficient plants. However, the mechanism of phosphite effects on plants is still widely unknown. In this paper we analysed uptake, subcellular distribution and metabolic effects of Phi in tobacco BY-2 cells using in vivo(31)P nuclear magnetic resonance ((31)P-NMR) spectroscopy. Based on the kinetic properties of the phosphate transport system of tobacco BY-2 cells, it was demonstrated that phosphite inhibited phosphate uptake in a competitive manner. To directly follow the fate of phosphate and phosphite in cytoplasmic and vacuolar pools of tobacco cells, we took advantage of the pH-sensitive chemical shift of the Phi anion. The NMR studies showed a distinct cytoplasmic accumulation of Phi in Pi-deprived cells, whereas Pi resupply resulted in a rapid efflux of Phi. Pi-preloaded cells shifted Phi directly into vacuoles. These studies allowed for the first time to follow Phi flux processes in an in vivo setting in plants. On the other hand, the external Pi nutrition status and the metabolic state of the cells had a strong influence on the intracellular compartmentalization of xenobiotic Phi.
authors.affiliation: Martin Luther University of Halle-Wittenberg, Biocenter, 06120 Halle, Germany.
authors.forename: Ralitza
authors.initials: R
authors.lastname: Danova-Alt
authors.forename: Cor
authors.initials: C
authors.lastname: Dijkema
authors.forename: Pieter
authors.initials: P
authors.lastname: DE Waard
authors.forename: Margret
authors.initials: M
authors.lastname: Köck
mesh_terms: D001692:Biological Transport; D002451:Cell Compartmentation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010710:Phosphates / Q000378:metabolism; D017905:Phosphites / Q000378:metabolism*; D014026:Nicotiana / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism
chemical_list: D010710:Phosphates; D017905:Phosphites