Abstract
Iron acquisition by gramineous plants is characterized by the secretion of phytosiderophores and subsequent uptake of iron as an Fe-phytosiderohore complex. Genes encoding Fe-phytosiderophore transporter have been isolated in maize (ZmYS1) and barley (HvYS1). In contrast to HvYS1, which specifically transports Fe-phytosiderophore, ZmYS1 has broad substrate specificities. Here, we further characterized the ZmYS1 in terms of tissue-specific expression and cellular localization. The expression of ZmYS1 was induced by Fe-deficiency, but unlike HvYS1, the expreesion was found in both the roots and the shoots. Moreover, the expression of ZmYS1 was higher in the shoots than in the roots. In the shoot, the expression was higher in the young leaf showing severe chlorosis than in the old leaf staying green. Unlike barley, maize did not show a distinct diurnal rhythm in both the secretion of phytosiderophore and the expression of ZmYS1. Immunostaining showed that ZmYS1 was localized on the root epidermis.
