Abstract
Graminaceous plants including rice utilize a chelation strategy to acquire Fe from the soil. The roots of these species release low-molecular weight compounds, called mugineic acid family phytosiderophores (MAs), which bind to and solubilize Fe(III) in the rhizosphere. Previously, we reported that rER-vesicles which were proposed to be involved in MAs biosynthesis were observed in iron-deficient rice roots, and OsNAS2:sGFP fusion protein, the enzyme participating in the MAs synthesis pathway, was localizes as small spots in the cytoplasm of the transgenic rice roots (Nozoye et al., JSPP 2008). Two motifs involved in cellular vesicle transport (tyrosine motif and di-leucine motif) were conserved in all NAS protein identified so far. In this report, we introduced the mutations into these motifs and observed the localization of mutated proteins in the transgenic rice root cells. The mutated OsNAS2 in tyrosine motif localized in the vesicles, however these vesicles cohered and could not move. On the other hand, the OsNAS2 mutated in di-leucine motif did not localize to these vesicles. It was suggested that MAs-vesicles were systematically transported in the rice root cells.
