Probable reductase that might be involved in the reduction of lariciresinol into secoisolariciresinol. In most plant species, a single enzyme is able to reduce both pinoresinol and lariciresinol efficiently while in Arabidopsis, PRR1 and PRR2 show a strict substrate selectivity for pinoresinol. Dimer. Belongs to the NmrA-type oxidoreductase family. Isoflavone reductase subfamily.