Catalyzes the NAD(+)-dependent oxidation of formate to carbon dioxide (PubMed:8278546). Involved in the cell stress response. Involved in formate-dependent oxygen uptake coupled to ATP synthesis (PubMed:9490763). formate + NAD(+) = CO2 + NADH Homodimer. Found at high levels in developing tubers, at intermediate level in stems, veins, stolons, and stamens, and at low level in leaves and roots. Induced very rapidly by wounding, and slower by darkness, chilling, drought, hypoxia, and treatments with formate, abscisic acid, serine, sarcosine, pyruvate, acetate, ethanol or methanol. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family. FDH subfamily. There are two other putative pseudogenes, FDH2 and FDH3.