Maintains high levels of reduced glutathione in the cytosol. May play a role in the restoration of the post-stress redox state of the cytosolic glutathione pool. 2 glutathione + NADP(+) = glutathione disulfide + H(+) + NADPH Binds 1 FAD per subunit. Increased expression in the recovery (post-stress) phases of both drought and chilling. The active site is a redox-active disulfide bond. Belongs to the class-I pyridine nucleotide-disulfide oxidoreductase family.