NADH-dependent glutamate synthase participated in ammonium assimilation in Arabidopsis root

Higher plants have 2 GOGAT species, Fd-GOGAT and NADHGOGAT. While Fd-GOGAT mainly assimilates ammonium in leaves, which is derived from photorespiration, the function of NADH-GOGAT, which is highly expressed in roots,1 needs to be elucidated. The aim of this study was to clarify the role of NADH-GOGAT in Arabidopsis roots. The supply of ammonium to the roots caused an accumulation of NADH-GOGAT, while Fd-GOGAT 1 and Fd-GOGAT 2 showed no response. A promoter–GUS fusion analysis and immunohistochemistry showed that NADH-GOGAT was located in nongreen tissues like vascular bundles, shoot apical meristem, pollen, stigma, and roots. The localization of NADH-GOGAT and Fd-GOGAT was not overlapped. NADHGOGAT T-DNA insertion lines showed a reduction of glutamate and biomass under normal CO₂ conditions. These data emphasizes the importance of NADHGOGAT in the ammonium assimilation of Arabidopsis roots.