The color varieties of sunflower pollen are determined by two interacting loci: A_B_ gives orange pollen, aaB_ gives yellow, and _ _bb produces cream colored. Assume that two fully heterozygous plants are crossed. Give the phenotypes (with frequencies) of the offspring. What type of gene interaction would account for these results?

This is an illustration of epistasis type of gene interaction.

Explanation:

On crossing AaBb * AaBb, the offspring produced are mentioned in the Punnett square given in the attachment below. Based on the Punnett square, the phenotypic ratio will be 9 (orange): 4 (cream) : 3 (yellow).  

The given case is an illustration of the epistasis kind of gene interaction. When two or more distinct gene loci take part in the formation of similar phenotype, however, not additively is termed as epistasis, that is, it is the non-allelic association between the alleles situated at a distinct gene locus. In the phenomenon of epistasis, one of the gene loci modifies or masks the phenotype of a second gene locus.