Dominant Epistasis, Supplementary gene interaction or recessive epistasis are considered the most difficult concepts.
23 Questions around this concept.

Solve by difficulty

If a plant produce green coloured fruit in summer squash, its genotype would be:

WwYy

wwyy

WWYY

WwYY

What is dominant epistasis?

It is a type of epistasis in which the dominant allele of one gene masks the expression of another gene.

It is a type of epistasis in which the recessive allele of one gene masks the expression of another gene.

It is a type of epistasis in which the expression of one gene is completely dependent on the expression of another gene.

It is a type of epistasis in which two genes interact to produce a novel phenotype.

Concepts Covered - 2

Dominant Epistasis

According to Mendel’s laws of inheritance, when two contrasting alleles are brought together, one of them dominates over the other in F1.
In the phenomenon of epistasis, two independent non-allelic genes that affect the same phenotype interact in such a way that the dominant allele of one gene (for example, A) masks the effect of another gene (for example B).
Therefore, gene A is said to be epistatic to gene B or gene B is said to be hypostatic to gene A.

Example:

In summer squash, the fruit colour is governed by two genes.
The dominant gene W for white colour, suppresses the expression of the gene Y which controls yellow colour.
So yellow colour appears only in the absence of W. Thus W is epistatic to Y.
In the absence of both W and Y, green colour develops.

Supplementary gene interaction or recessive epistasis

When recessive alleles at one locus mask the expression of both (dominant and recessive) alleles at another locus, it is known as recessive epistasis.
This type of gene interaction is also known as supplementary epistasis.
An example of recessive epistasis is pigmentation in mice which is controlled by two pairs of genes A/a and C/c.
Dominant C produces black colour when gene A/a is recessive homozygous.
When gene A is homozygous recessive or heterozygous with gene C/c, agouti is produced.
However, when gene C/c is homozygous recessive, it masks the formation of any color and albino/white coat is produced.
Therefore, gene C/c is being epistatic in recessive homozygous condition.
This happens because a mouse with a recessive c allele at this locus is unable to produce pigment and is albino regardless of the allele present at locus A.