Abstract
Nicotinamide nucleotides (NAD and NADP) are important co-factors in various metabolic processes in living organisms. Although both NAD and NADP are redox regulators of living cells, these compounds likely play overlapping but different roles in other biological processes. NAD and NADP are synthesized in NAD biosynthetic pathway comprising NADS, NMNAT, and NADK. The levels of NAD and NADP appear to be regulated by these enzymes. In this study, we analyzed transgenic Arabidopsis plants, which have several levels of NAD and NADP to elucidate the regulating mechanisms of these co-factors. Our results showed that the decrease of NADP level inhibited photosynthetic electron transport. Furthermore, fluctuation of NAD and NADP levels affected several metabolite processes, indicating that NAD and NADP are key factors that control plant metabolism and also suggest the possibility that enhancement of co-factor synthesis is a workable strategy for improving performances of plant.
