The kernel color in wheat is a continuous trait determined by two additive genes, each with two alleles, that equally contribute to kernel color determination. The red kernels are determined by two genes and two dominant alleles (R1R1R2R2), and white kernels are determined by two recessive alleles at the same two genes (r1r1r2r2). The duplicate dominant alleles R1 and R2 contribute equally to kernel color and cumulatively control the intensity of the red kernel phenotype. Both these alleles are dominant over the recessive white alleles r1 and r2. A true breeding red plant and true breeding white plant are crossed, and the resulting F1 progeny are selfed. What is the expected phenotypic ratio of the kernel progeny of the F2 offspring?

Duplicate dominant epistasis may be defined as a type of epistasis in which the dominant gene are responsible for masks the expression of recessive alleles at two different loci. This is also known as duplicate gene action.

The red kernels have genotype R1R1R2R2 and white kernel have genotype r1r1r2r2. The cross between them result in the F1 generation with R1r1R2r2 ( all red kernels). The selfing of the F1 generation result in the generation of progeny with 15 red kernels and 1 white kernels. The white kernels is obtained due to the absence of both the dominant alleles. 15 ratio of red kernels are obtained because the single dominant gene either R1 or R2 is enough for the formation of red kernels.

Thus, the answer is 15 (red) : 1 (white).