Question

Fruit color in squash is an example of-
A. Dominant epistasis
B. Recessive epistasis
C. Inhibitory genes
D. Complementary genes

Answer 1

Epistasis is the phenomenon of masking the effect of the other allele.Epistasis word literally means to hide or mask. Summer squash fruit colour is a classical example of this phenomenon which is interesting genetics.

Complete answer:
Epistasis is the phenomenon on which there is interaction between genes that is opposite, as one gene masks the expression of another. The gene which is being silenced is called Hypostatic and the gene which masks is called Epistasic.
There are two types, dominant and recessive.
In dominant epistasis, a dominant gene silences the other non-allelic gene. The summer squash fruit colour can be white, yellow or green. White fruits producing epistatic alleles are 'W'. Y is for yellow fruits which is dominant to y which is for green fruits. White masks the effect of yellow or green. Hybrid ratio obtained is 12 white: 3 yellow: 1 green.
In recessive epistasis ,the expression of one gene pair depends on the other gene pair. One gene must be expressed for another gene expression. Ratio obtained is 9:3:4
Complementary genes is a gene interaction in which both genes have the ability to mask the effect of the other. We can understand it as the concept in which dominant forms of both genes are necessary for the characteristic to be seen.
A gene that inhibits an active allele present at different locus is known as inhibitory gene. In inhibitory gene interaction, one dominant gene which is inhibitory prevents the expression of another dominant gene.

So, the correct answer is “Option A”.

Note:
Ratio for inhibitory genes is 13:3 and for complementary genes is 9:7. They are also a very important phenomenon considering genetics. They modify the standard mendelian ratio i.e. 9:3:3:1.