Abstract
An association was found earlier between the Ep(1) gene locus coding for an endopeptidase and the endosperm color gene Y(1) on chromosome 6 of Zea mays. By employing primary trisomics we have unequivocally placed the Ep(1) gene on chromosome 6, closely linked to the Y(1) locus. Additionally we describe new alleles at the Ep(1) locus, and present evidence for the existence of a second endopeptidase system in maize.