GENETIC-MARKER TRANSMISSION IN EARLY GENERATION COMMON X TEPARY BEAN HYBRIDS

A set of BC1F2 populations derived from common bean x tepary bean inte rspecific hybrids was examined for isozyme segregation within 12 diffe rent enzyme systems. The BC1F1 parents of the BC1F2 populations, as in ferred from the BC1F2 progeny data, were found to be heterozygous for approximately half of the marker loci examined, in agreement with tran smission genetic theory predictions. In contrast, segregation ratios f or isozyme loci in the BC1F2 families deviated significantly from expe cted Mendelian ratios in approximately 50% of the cases, due to a seve re deficiency of individuals homozygous for the tepary allele, as well as having a deficiency of heterozygotes in some cases. Using data fro m a diagnostic pair of linked isozyme loci, evidence of intergenomic r ecombination at. levels equal to or greater than that encountered in i ntraspecific crosses was detected in one BC1F2 family.