Reductase involved in lignan biosynthesis. Catalyzes the enantioselective sequential conversion of (-)-pinoresinol into (-)-lariciresinol and of (-)-lariciresinol into (+)-secoisolariciresinol. Can also convert with a lower efficiency (+)-pinoresinol into (+)-lariciresinol, but not (+)-lariciresinol into (-)-secoisolariciresinol. Abstracts the 4R-hydride from the NADPH cofactor during catalysis. (+)-lariciresinol + NADP(+) = (+)-pinoresinol + H(+) + NADPH (-)-lariciresinol + NADP(+) = (-)-pinoresinol + H(+) + NADPH (+)-secoisolariciresinol + NADP(+) = (-)-lariciresinol + H(+) + NADPH Dimer. Phe-164, Val-268 and Leu-272 are involved in enantiospecific binding of (-)-pinoresinol while in PLR_Tp2, a 'Gly-268' and a symmetric substitution between Phe and Leu favor binding of the (+)-antipode of pinoresinol. Belongs to the NmrA-type oxidoreductase family. Isoflavone reductase subfamily.