Catalyzes the NADPH-dependent reduction of glyoxylate and hydroxypyruvate (HP) into glycolate and glycerate in the cytoplasm, thus providing a cytosolic bypass to the photorespiratory core cycle. Mostly active in the presence of NADPH and hydroxypyruvate. glycolate + NADP(+) = glyoxylate + H(+) + NADPH (R)-glycerate + NAD(+) = 3-hydroxypyruvate + H(+) + NADH (R)-glycerate + NADP(+) = 3-hydroxypyruvate + H(+) + NADPH Strongly inhibited by oxalate. Homodimer. Elevated levels of hydroxypyruvate and other metabolites in leaves. Under long-day conditions, slightly altered photosynthetic gas exchange. When associated with HPR1 disruption, strong air-sensitivity and dramatic reduction in photosynthetic performance. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family. GyaR subfamily.