Abstract
Recent studies have revealed that cytokinin is a signaling molecule involved in the propagation of nitrogen signals throughout the whole plant cells for an integrated network of intracellular and inter-organ signaling of nitrogen availability in addition to nitrate itself. In previous study, we reported that one of the isopentenyltransferase in Arabidopsis, AtIPT3, is a key determinant of nitrogen-dependent cytokinin biosynthesis. In rice, seven genes of isopentenyltransgerase (OsIPT1-5, 7-8) were identified as the genes involved in the cytokinin biosynthesis. The intracellular localization of each gene products is observed in chloroplast, mitochondrion, or cytosol, respectively. We analyzed gene expression of OsIPTs in the nitrogen-treated rice root. As the results, we found that some OsIPTs were preferentially induced by ammonium ion rather than nitrate ion. The induction of OsIPTs were also observed by the addition of external glutamine. We will discuss the mechanism for nitrogen-inducible gene expressions in those OsIPTs.
