Incomplete dominance

Incomplete dominance; no allele completely dominates the other i.e. all alleles express themselves equally.

In genetic crosses involving incomplete dominance, two different capital letters are used to represent the two genes.

Example;

in some plants such as Mirabilis jalapa (4 o’clock plant) a cross between red and white flowered plants results in F1 generation with all the plants bearing pink flowers thus showing blending of colour. Self-pollinating the F1 individuals give phenotypic ratio of 1 red: 2 pink: 1 white. Let R represent the gene for red flower colour. Let W represent the gene for white flower colour.

Selfing the pink flowered plants