Question

Which of the following cross can demonstrate the polygenic inheritance of colour of wheat kernel?

• A. Homozygous dominant for both gene and heterozygous dominant for both gene
• B. Homozygous dominant for both gene and homozygous dominant for both gene
• C. Heterozygous dominant for both gene and heterozygous dominant for both gene
• D. None of the above

Answer 1

The correct option is A Homozygous dominant for both gene and heterozygous dominant for both gene

Polygenic inheritance describes the inheritance of traits that are determined by more than one gene. One wheat variety with a gene for dark red colour that is homozygous dominant is crossed with another variety which has a homozygous recessive gene for white colour. The red colour in the wheat kernel is incompletely dominant over white hence the F${}_1$ hybrid has a kernel intermediate between red and white i.e. medium red. The offspring of the F${}_1$ generation are heterozygous dominant for both genes. Thus when F${}_1$ hybrids are crossed to get the F${}_2$ generation the kernel colour has a range dark red, medium dark red, medium red, light red and white in the ratio 1:4:6:4:1.