GENETIC AND LINKAGE ANALYSIS OF ISOZYME POLYMORPHISMS IN FLAX

In an initial step toward developing a genetic map of flax (Linum), the inheritance and linkage relationships of seven isozyme polymorphisms were studied. Three polymorphic loci-Dia1, Pgm1, and Ap-1, each with codominant alleles-were found responsible for the mobility variants observed on diaphorase, phosphoglucomutase, and acid phosphatase-stained gels, while three polymorphic loci-Ap-2, Lap1, and Pgd1, each with recessive null alleles-were found responsible for the observed acid phosphatase, leucine aminopeptidase, and 6-phosphogluconate dehydrogenase variants with missing bands. An additional leucine aminopeptidase variant with a missing band was found to be the result of a seventh polymorphic locus (Lap2), which has incompletely dominant null and normal activity alleles. The loci Dia 1 and Pgm 1 were found to be linked approximately 28 cM apart, while all 16 additional pairs of loci tested segregated independently. Analysis of 25 near-isogenic lines (NILs), each selected for the rust resistance genotype of its nonrecurrent parent, indicated that Pgd1 may be linked with the M rust resistance loci.