Q.Describe dominant epistasis with an example.

Step 1. Dominant epistasis is a form of intergenic (non-allelic) gene interaction in which a dominant allele at one locus interferes with and masks the phenotypic expression of a different gene's alleles at another locus.

Step 2. In summer squash, fruit colour is controlled by two loci: the first has a dominant allele W for white fruit and a recessive allele w for coloured fruit, while the second, hypostatic locus has a dominant allele G for yellow fruit and a recessive allele g for green.

Step 3. Crossing a white fruit (WWgg) with a yellow fruit (wwGG) gives an all-white, heterozygous F1 (WwGg), because the dominant W allele masks the colour locus outright; selfing this F1 gives an F2 in which every genotype carrying at least one W allele (12 of 16 combinations) is white, while only the double-recessive ww genotypes (4 of 16) show any colour, splitting further by the G locus into 3 parts yellow and 1 part green. …

Define dominant epistasis and walk through the summer squash cros …

• Confusing dominant epistasis's 12:3:1 ratio with the standard 9:3:3:1 dihybrid ratio. …