Abstract
The three members of the rice OsAMT1 gene family of ammonium transporters show distinct expression patterns; constitutive and ammonium-promoted expression in shoots and roots for OsAMT1;1; root-specific and ammonium-inducible expression for OsAMT1;2; root-specific and nitrogen-repressible expression for OsAMT1;3. Ammonium application to roots following a period of nitrogen starvation induced mRNA accumulation of OsAMT1;1 and OsAMT1;2, but a decrease of OsAMT1;3 mRNA levels. The expression patterns of the three genes showed good correlation with the root tissue contents of glutamine but not of ammonium. Glutamine application mimicked the ammonium effects, indicating that glutamine rather than ammonium controls the expression of ammonium transporter genes in rice. These results imply that rice possesses unique mechanisms of adaptation to variable nitrogen sources in the soil.
We will also report physiological analyses of transgenic rice expressing the OsAMT1;2 driven by CaMV35S promoter.
