Abstract
Boron (B) is an essential elements for higher plants. Recently, AtNIP5;1, a member of Major Intirinsic Protein family, was identified as a boric acid channel responsible for efficient root uptake of B in Arabidopsis (Takano et al., 2006). To reveal the molecular mechanisms of B transport in rice, we analyzed OsNIP3;1, a rice gene most similar to AtNIP5;1.
Accumulation of OsNIP3;1 transcripts was induced by several fold upon exposure to B limitation in roots. GFP-OsNIP3;1 fusion protein mainly localized to the plasma membrane in tobacco BY2 cells. Tissue specificity of OsNIP3;1 was investigated with transgenic plants carrying Promoter:GUS fusion gene. In roots, GUS staining was observed both in steles and outer cortex cells. In leaf blades, GUS staining was observed in cells around vesicular bundles. These data suggest that OsNIP3;1 is an B- inducible channel involved in both root uptake and distribution of B in rice plants.
