Catalyzes the initial reaction in the xylose utilization pathway by reducing D-xylose into xylitol. Xylose is a major component of hemicelluloses such as xylan. Most fungi utilize D-xylose via three enzymatic reactions, xylose reductase (XR), xylitol dehydrogenase (XDH), and xylulokinase, to form xylulose 5-phosphate, which enters pentose phosphate pathway (By similarity). NAD(+) + xylitol = D-xylose + H(+) + NADH NADP(+) + xylitol = D-xylose + H(+) + NADPH Carbohydrate metabolism; D-xylose degradation. Overexpressed during growth on both D-xylose or L-arabinose compared to D-glucose. Significantly expressed during late stages of infection of barley leaves. Belongs to the aldo/keto reductase family.