Abstract
In rice, glutamine (Gln) regulates expression of several key genes for nitrogen metabolism including NADH-glutamate synthase1 (NADH-GOGAT1) and NAD-isocitrate dehydrogenase (IDH) genes. However, molecular mechanisms of Gln-signal transduction in plants are unknown. We have focused on a nuclear localizing OsACR9 in rice as a candidate for the Gln sensor since cellular distribution of OsACR9 overlapped with those of NADH-GOGAT1 and IDH in various rice organs. To investigate whether OsACR9 may be involved in Gln-signaling in rice, we searched rice genes expressed in a Gln- and OsACR9-dependent manner by microarray analysis. Comparative-transcriptome profiling in rice roots treated with L-methionine sulfoximine plus NH4+ and/or Gln, provided 388 candidate genes expressed in a Gln-dependent manner. Expression of 59 genes of these candidates was altered in roots of RNAi-mediated OsACR9-knockdown rice. A yeast two-hybrid screening for OsACR9-interacting rice proteins is in progress. Involvement of OsACR9 in Gln-signaling in rice will be discussed.
