Catalyzes a reversible NAD-dependent dehydrogenase reaction involved in central metabolism and redox homeostasis between organelle compartments (Probable). Peroxisomal NAD-dependent malate dehydrogenase involved in fatty acid beta-oxidation. Reoxidizes NADH from the beta-oxidation and provides NAD for the conversion of fatty acyl-CoA to acetyl-CoA. Does not participate directly in the glyoxylate cycle (PubMed:17376163, PubMed:19812894). Required for maintenance of photosynthetic rates under photorespiratory conditions, and carbon flow during photorespiration. Supplies NADH reductant to the peroxisomal hydroxypyruvate reductase (HPR), which reduces hydroxypyruvate into glycerate in the photorespiratory cycle (PubMed:18685043). (S)-malate + NAD(+) = H(+) + NADH + oxaloacetate Homodimer. Expressed in rosette leaves at low levels. No visible phenotype under normal growth conditions, but the double mutant plants pmdh1 and pmdh2 show seedling growth arrest 5 days after seed imbibition. Belongs to the LDH/MDH superfamily. MDH type 1 family.