Probable thiol-disulfide oxidoreductase required for pollen tube growth and pollen function in the pistil. Seems not to be required for in vitro pollen tube growth. May be involved in the generation of lipid signaling molecules in pistil. [protein]-dithiol + NAD(+) = [protein]-disulfide + H(+) + NADH [protein]-dithiol + NADP(+) = [protein]-disulfide + H(+) + NADPH Disruption of pollen tube growth in the pistil and reduction in the ability to target ovules. Belongs to the nucleoredoxin family.