Formate dehydrogenase takes part in molybdenum and iron homeostasis and affects dark-induced senescence in plants

Formate is produced, in plants, by various biochemical pathways and it is degraded by Formate Dehydrogenase FDH, in presence of NAD⁺, into CO₂ and NADH. FDH has been proposed as one of the enzymes regulating molybdenum (Mo) and iron (Fe) homeostasis. Here we explored the impact of FDH perturbation on Mo and Fe plant nutritional status and FDH relevance on the plant responses against abiotic stresses, by using <i>in silico</i> and experimental approaches. The characterization of different <i>Arabidopsis thaliana</i> and <i>Nicotiana tabacum</i> FDH transgenic lines suggests that FDH promoter activity is dependent on both Mo and Fe nutritional supply and that FDH overexpression alters Mo concentrations in seeds and Fe concentration in seeds, leaves and stems. Also, FDH overexpression delays the dark-induced senescence whereas the lack of FDH accelerates its progression. FDH is therefore a multifaceted enzyme with impact on Mo and Fe homeostasis and regulation of dark-induced senescence.