The tetraploid (2n = 4x = 28) rose 86-7 (
Rosa wichuraiana R. rugosa rubra) and its hybrids with the thornless tetraploid rose cultivar Basye's Blueberry (2n = 28) were analyzed for meiotic configuration frequencies and meiotic abnormalities. Genomic relationships in these hybrids were interpreted with the aid of a model of meiotic chromosome association in tetraploids. The closest-fitting model solutions indicated a 2:2 (AABB) pattern of genomic relationships, with 65% to 90% of all association between most closely related genomes. Some of the optimal solutions were transitional to a ring4 pattern, in which one of the possible pairing arrangements is suppressed. The same configuration frequencies could also reflect a 4:0 pattern of equally similar genomes with fractionally more than two independent pairing and chiasma-forming domains per chromosome. Observed meiotic abnormalities included chromosome stickiness and asynchronous chromosome contraction within cells. Pollen stainability varied independently of meiotic irregularity or multivalent frequency. The observed configuration frequencies are consistent with partially tetrasomic inheritance that retains considerable heterozygosity, but allows individual contributions from parental genomes to become homozygous.