The use of the zinc-fluorophore, Zinpyr-1, in the study of zinc homeostasis in Arabidopsis roots.

* The usefulness of the zinc (Zn)-fluorophore, Zinpyr-1, to examine the localization of Zn in the roots of Arabidopsis has been investigated. * In wild-type roots Zinpyr-1 fluorescence was predominantly in the xylem. The fluorescence signal was abolished by the application of the Zn-chelator, N,N,N',N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and was increased by increasing exogenous Zn in the medium, indicating that fluorescence reflected relative Zn concentrations. * In the hma2, hma4 double mutant, which is deficient in root to shoot Zn translocation, Zinpyr-1 fluorescence was low in the xylem and high in the adjacent pericycle cells in which HMA2 and HMA4 are specifically expressed in a wild type. Zinpyr-1 fluorescence was also increased in the endodermis. * These results show that Zinpyr-1 can be used to examine the effects of mutations in Zn transporters on the localization of Zn in Arabidopsis roots and should be a useful addition to the tools available for studying Zn homeostasis in plants.