If a wheat variety of red kernels is crossed with white-kernelled wheat, what would be its genotypic ratio? (Note: It is a polygenic trait controlled by 2 pairs of polygenes.)

Question

If a wheat variety of red kernels is crossed with white-kernelled wheat, what would be its genotypic ratio? (Note: It is a polygenic trait controlled by 2 pairs of polygenes.) (A) 9:7 (B) 1:10:4:1 (C) 1:4:6:4:1 (D) 1:2:4:2:4:2:1

Tardigrade Admin · Accepted Answer

When traits are controlled by three or more genes, they are called polygenic traits and their inheritance is called as polygenic inheritance. Polygenic inheritance is influenced by the environment as well and not just the polygenes.
Kernel colour of wheat is regulated AA and BB that is two pairs of genes. Genes A and B express the red colour of kernel. They are dominant over their recessive alleles. When a red kernel wheat variety is crossed with white kernel wheat, the ratio obtained in

F_{2}

is

1 : 4 : 6 : 4 : 1

due to the polygenic inheritance.

Q. If a wheat variety of red kernels is crossed with white-kernelled wheat, what would be its genotypic ratio? (Note: It is a polygenic trait controlled by 2 pairs of polygenes.)

$9 : 7$

$1 : 10 : 4 : 1$

$1 : 4 : 6 : 4 : 1$

$1 : 2 : 4 : 2 : 4 : 2 : 1$