Question

Fruit colour in squash is an example of

• A. Recessive epistasis
• B. Dominant epistasis
• C. Complementary genes
• D. Inhibitory genes

Answer 1

The correct option is B Dominant epistasis

• A dominant epistasis is a condition when a dominant gene masks the effect of the other non-allelic gene.
• In summer squash, the fruit color may be white, yellow, or green.
• White fruits are produced by a domain epistatic allele 'W'.
• At another locus, Y for yellow fruits is dominant to its allele y for green fruits.
• Dominant white hides the effect of yellow or green.
• A consequence of this dominant epistasis is that the hybrid ratio is modified into 12 white: 3 yellow: 1 green. So, dominant epistasis suppresses the expression of a non-allelic gene (dominant or recessive).

Thus, the correct answer is option B.