Linkage groups in the genetic map of Allium cepa. Map distances (in cM) are to the left, and locus designations are to the right of each group. RFLP loci are indicated by clone designations of AOB, AJB, AJK, or API. Prefixes are followed by numbers, reflecting the order of clone isolation, then by an abbreviation for the restriction enzyme-generating polymorphic fragments detected by the clone (E1, E5, H3, and B1 for EcoRI, EcoRV, HindIII, and BamHI, respectively), then by estimated sizes (in kb) of polymorphic fragments as AC43 fragment/BYG15-23 fragment. RAPD loci are indicated by the primer followed by sizes in kilobases of the mapped polymorphic PCR products