Abstract
Nicotianamide nucleotides (NAD(P)(H)) are essential molecules, involved not only in well known electron transport and oxidation-reduction reactions, but also in cellular signaling. Quantities of these molecules are regulated by nicotianamide mononucleotide adenyltransferase (NMNAT), NAD synthetase (NADS), and NAD kinase (NADK). To analyze the molecular interaction between NAD metabolism and plant growth, we characterized knockout and overexpression arabidopsis plants. The knockout plant of AtNMNAT demonstrated abnormality in pollen tube growth. A T-DNA inserted plant in NADK2, which encodes a plant specific chloroplast-localizing NADK, demonstrated a pale green phenotype and decreased number of rosette leaves. In contrast, the transgenic plant overexpressing NADK2 under the control of 35S promoter showed increases in enzyme activities and metabolites in calvin cycle, resulted in accumulation of chlorophylls and amino acids. Furthermore, a nitrogen metabolism was also affected in NADK2 overexpressed and knockout plants. These results demonstrate that NAD-related metabolites regulate plant metabolism in whole plant level.
