Abstract
NADH-glutamate synthase (NADH-GOGAT) catalyzes the transfer of the amido-residue of glutamine to 2-oxoglutarate, resulting generation of two glutamate molecules. There are two genes encode two isoenzymes of NADH-GOGAT, i.e. NADH-GOGAT1 and NADH-GOGAT2 in rice. We have showed that NADH-GOGAT1 protein accumulated in vascular tissues of developing organs, such as unexpanded leaves and young grains. On the other hand, NADH-GOGAT2 promoter activity was mainly detected in vascular tissues of senescing leaves. However, their physiological functions are unknown. We isolated Tos17-insertion mutants lacking either NADH-GOGAT1 or NADH-GOGAT2. These mutants were cultivated till harvest in paddy field. Top dry weight and grain yield were decreased in both of NADH-GOGAT1 and NADH-GOGAT2 mutants. The NADH-GOGAT1 mutants decreased panicle number per plants, while spikelet number per panicle was mainly reduced in NADH-GOGAT2 mutants. These phenotypic characteristics suggest that NADH-GOGAT1 and NADH-GOGAT2 probably possess distinct functions on nitrogen utilization, respectively in rice.
