Question

Which of the following is an example of fruit colour in squash?

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

Answer 1

The correct option is B

Dominant epistasis

The correct option is B.

Explanation for correct option:

1. When a dominant gene covers the action of another non-allelic gene, this is known as dominant epistasis.
2. Summer squash fruits can be white, yellow, or green in color.
3. A domain epistatic allele '$W$' produces white fruits.
4. $Y$ for yellow fruits is dominant over its gene y for green fruits at another location.
5. The influence of yellow or green is hidden by the dominant white.
6. The hybrid ratio is changed to $12white:3yellow:1green$ as a result of this dominating epistasis.
7. As a result, dominant epistasis prevents a non-allelic gene from expressing.

Explanation for incorrect options:

Option A:

1. The complementary gene is the result of the interaction of two dominant non-interallelic genes.
2. Each of these has its own effect, but when they interact, a new trait emerges.
3. The Mendelian ratio of $9:3:3:1$ is transformed to $9:7$ due to the linkage of both genes.
4. Sweet pea plants' flower color is an example of it.

Option C:

1. An inhibitory gene is one that suppresses the expression of an active allele located at another locus.
2. Pigmentation in rice is an example of it.

Option D:

1. Recessive epistasis occurs when recessive alleles at one locus hide the expression of both types of alleles (recessive and dominant) at another locus.
2. Supplementary epistasis is the term for this sort of gene interaction.
3. Grain color in maize is a nice illustration of such gene interaction.

Final Answer: Fruit color in squash is an example of dominant epistasis.