Catalyzes the NADH-dependent reduction of hydroxypyruvate into glycerate in the photorespiratory core cycle. Mediates fatty acid beta-oxidation in germinating seeds when malate dehydrogenase is absent. (R)-glycerate + NAD(+) = 3-hydroxypyruvate + H(+) + NADH Slightly inhibited by oxalate. Photosynthesis; photorespiration; 3-phospho-D-glycerate from glycine: step 3/4. Present in leaves (at protein level). Mostly expressed in photosynthetic tissues such as leaves, stems, flowers, buds, and, to a lower extent, in siliques and roots. Induced by drought. Accumulates in response to light, but transiently repressed in darkness. Very low NADH-dependent hydroxypyruvate reductase activity in leaves. Under short days, slower growth and delayed bolting. Slight accumulation of metabolites with long turnover half-times that become dissimilated during the dark. Perturbated photorespiration-related gas exchange. When associated with HPR2 disruption, strong air-sensitivity and dramatic reduction in photosynthetic performance. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family.