Enhancement of NH4+ uptake by NO3- in relation to expression of nitrate-induced genes in rice (Oryza sativa) roots

摘要

This study aimed to survey the expression of genes involved in rice N uptake and assimilatory network and to understand the potential molecular mechanisms responsible for the NO3--enhanced NH4+ uptake. By using quantitative real-time polymerase chain reaction (PCR), the genes related to N nutrition, including ammonium transporters (AMTs) and ammonium assimilatory enzymes (GS and GOCAT), were transcriptionally analyzed in rice plants grown in the absence and presence of NO3- in the NH4+-containing medium. The results showed that NH4+ uptake by rice was enhanced by the NO3- supply to the medium. At the same time and in parallel, the amount of transcripts of seven genes (OsAMT1;1, OsAMT1;2, OsAMT4;1, OsGLN2, OsGLU1, OsGLT1, and OsGLT2) was increased in rice roots, but the expression of two genes (OsGLN1;1 and OsGLN1;2) was decreased and that of OsAMT1;3 remained without change. Up- or down-regulation of these genes involved in NH4+ uptake and assimilation correlated with the increase in NH4+ uptake in the presence of NO3- in rice roots.