Influence of different nitrogen inputs on the members of ammonium transporter and glutamine synthetase genes in two rice genotypes having differential responsiveness to nitrogen.

Two aromatic rice genotypes, Pusa Basmati 1 (PB1) and Kalanamak 3119 (KN3119) having 120 and 30 kg/ha optimum nitrogen requirement respectively, to produce optimal yield, were chosen to understand their differential nitrogen responsiveness. Both the genotypes grown under increasing nitrogen inputs showed differences in seed/panicle, 1,000 seed weight, %nitrogen in the biomass and protein content in the seeds. All these parameters in PB1 were found to be in the increasing order in contrast to KN3119 which showed declined response on increasing nitrogen dose exceeding the normal dose indicating that both the genotypes respond differentially to the nitrogen inputs. Gene expression analysis of members of ammonium transporter gene family in flag leaves during active grain filling stage revealed that all the three members of OsAMT3 family genes (OsAMT1;1-3), only one member of OsAMT2 family i.e., OsAMT2;3 and the high affinity OsAMT1;1 were differentially expressed and were affected by different doses of nitrogen. In both the genotypes, both increase and decline in seed protein contents matched with the expressions levels of OsAMT1;1, OsGS1;1 and OsGS1;2 in the flag leaves during grain filling stage indicating that high nitrogen nutrition in KN3119 probably causes the repression of these genes which might be important during grain filling.