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Beck, E; Renner, U: Ammonium triggers uptake of NO3- by Chenopodium-rubrum suspension-culture cells and remobilization of their vacuolar nitrate pool, Plant and Cell Physiology, 30, 487-495 (1989), doi:10.1093/oxfordjournals.pcp.a077767
Abstract:
Photoautotrophic cell suspension cultures of Chenopodium rubrum require high concentrations of nitrate and ammonium. During the growth phase total NH4+ and the greater portion of NH3− were consumed. During the stationary phase nitrate uptake continued but at a substantially smaller rate than during the growth phase. During growth the bulk of the absorbed N was incorporated into protein, the amount of which was then maintained constant until senescence. NH3− was accumulated upon transition between the growth and the stationary phase. NH3−, like the free amino acids, was deposited in the vacuole but, unlike these compounds, could not be remobilized upon transfer of the cells into N-free medium. Readdition of NH4+ to the medium, however, resulted in a mobilization of the vacuolar NH3−-pool. Reutilization of both vacuolar N-storage pools must have been accomplished by recycling from the vacuole to the cytoplasm because N-metabolizing enzymes could not be detected in isolated vacuoles. Transfer of the cells of the stationary phase into medium containing NH3− and NH4+ resulted in an induction of nitrate uptake by the cells, but only after a lag phase of 4–5 days. It is conceivable that NH4+ induces NH3−-translocating systems in the plasmalemma and in the tonoplast.

Letzte Änderung 30.06.2020