This invention provides an isolated nucleic acid encoding an endoplasmic reticulum oxidoreductin. The invention also provides recombinant expression cassettes comprising a polynucleotide encoding all or a portion of the endoplasmic reticulum oxidoreductin, wherein expression of the polynucleotide results in production of altered levels of the endoplasmic reticulum oxidoreductin in a transformed plant cell, or plants or seeds regenerated from the transformed cell.