Characterization of nitrite uptake in Arabidopsis thaliana: evidence for a nitrite-specific transporter

摘要: Summary Nitrite-specific plasma membrane transporters have been described in bacteria, algae and fungi, but there is no evidence of a nitrite-specific transporter higher plants. We used 13NO2 − to characterize nitrite influx into roots of Arabidopsis thaliana. Hydroponically grown Arabidopsis mutants, defective high-affinity nitrate transport, were distinguish between uptake by means the short-lived tracers 13NO3 −. This approach allowed us transporter. The Atnar2.1-2 mutant, lacking functional transport system, capable that constitutive thermodynamically active. The corresponding fluxes conform rectangular hyperbola, exhibiting saturation at concentrations above 200 μM (Km = 185 μM Vmax = 1.89 μmol g−1 FW h−1). Nitrite via putative nitrite transporter not subject competitive inhibition downregulated after 6 h exposure ammonium. These results signify existence Arabidopsis. enables which are incapable sustained growth on low nitrate, maintain significant nitrite. In wild-type plants, this flux may increase nitrogen acquisition also participate induction genes specifically induced