Populations segregating at locus Rm1 were used to measure recombination within two chromosome segments in Petunia hybrida. Gene Rm1 shows incomplete dominance and action that differs according to marker pair studied. It enhances recombination within the segment Hf1-Lg1 and restores it for the pair An2-Rt. Minor modifier genes exist, which act independent of or epistatic to Rm1 action. Like Rm1, they have effects that differ according to the chromosome segment analyzed, with the effects being more pronounced for strongly linked loci. Some of these genes are probably recessive.Key words: Petunia hybrida, gene Rm1, meiotic recombination, dosage effect.
Genetic control of mitochondrial malate dehydrogenases: evidence for duplicated chromosome segments.