Required for glycerol catabolism and involved in NADH/NAD(+) homeostasis (PubMed:12586344, PubMed:18599644). Essential for postgerminative growth and seedling establishment (PubMed:18599644). a quinone + sn-glycerol 3-phosphate = a quinol + dihydroxyacetone phosphate Polyol metabolism; glycerol degradation via glycerol kinase pathway; glycerone phosphate from sn-glycerol 3-phosphate (anaerobic route): step 1/1. Expressed in germinating seedlings. Also detected in roots, leaves, flowers, developing siliques and germinating seeds. Plants lacking SDP6 are impaired in gluconeogenesis during postgerminative growth. Belongs to the FAD-dependent glycerol-3-phosphate dehydrogenase family.