COMPLEMENTARY GENES FOR RED FLOWER COLOR IN ZONAL PELARGONIUMS

It is proposed that the inheritance of red flower colour in zonal pelargoniums is controlled by the interaction of two complementary genes, R1/r1 and R2/r2. The hypothesis was tested, and proven, by the observation of expected Mendelian segregation ratios following selfs and crosses within and between a wide range of red and non-red (salmon, pink and white) flowered plants. The relationship between red flower colours and non-red colours is one of epistasis and not one of dominance and recessiveness. Examples of all four of the expected red-flowered genotypes, and four out of the five non-red flowered genotypes, with respect to the two red genes, were discovered. Goodness of fit tests for the independent assortment of four other loci from that of the R2/r2 locus provided no evidence for linkage.