SEGREGATION AND RECOMBINATION OF SOLANUM BREVIDENS SYNTENY GROUPS IN PROGENY OF SOMATIC HYBRIDS WITH SOLANUM-TUBEROSUM - INTRAGENOMIC EQUALS OR EXCEEDS INTERGENOMIC RECOMBINATION

The Solanum brevidens genome (2n = 2x = 24) was examined with randomly applied polymorphic DNA (RAPD) markers in a second backcross populati on derived from a S. brevidens + S. tuberosum somatic hybrid. RAPD mar kers cosegregated into 12 different S. brevidens synteny groups. Most synteny groups were nonrecombinant,However, nearly 40% of the S. brevi dens synteny groups detected in this population were recombinant delet ions that carried at least one, but not all, synteny group-specific RA PD markers. Al S. brevidens synteny groups (except chromosome 5) were involved in recombination, and recombination occurred within most inte rvals between markers. About 20% of the recombinant S. brevidens synte ny groups involved a single synteny group-specific marker. The inherit ance of some single-marker representatives was followed in four BC3 fa milies. At least nine changes in S. brevidens synteny groups had occur red during backcrossing. Six of the nine changes involved translocatio n of S. brevidens markers between nonhomologous S. brevidens chromosom es, and three S. brevidens markers may have been introgressed into the potato genome.