Altered metabolism of chloroplastic NAD kinase-overexpressing Arabidopsis in response to magnesium sulfate supplementation

Abstract

Nicotinamide adenine dinucleotide (NAD)/NAD phosphate (NADPH) is essential for numerous redox reactions and serve as co-factors in multiple metabolic processes in all organisms. NAD kinase (NADK) is an enzyme involved in the synthesis of NADP+ from NAD+ and ATP. Arabidopsis NADK2 (AtNADK2) is a chloroplast-localizing enzyme that provides recipients of reducing power in photosynthetic electron transfer. When Arabidopsis plants were grown on MS medium supplemented with 5 mM MgSO4, an AtNADK2-overexpressing line exhibited higher glutathione and total sulfur accumulation than control plants. Metabolomic analysis of major amino acids and organic acids using capillary electrophoresis–mass spectrometry demonstrated that overexpression of AtNADK2 affected a range of metabolic processes in response to MgSO4 supplementation.