Answer to Question #89784 in Genetics for Victoria

Question

In some types of wheat, color is caused by two sets of genes. Both dominant genes A and E are needed for red color. White results from both recessive genes in the homozygous state (aaee). Other combinations will produce brown wheat grains. A strain with the genotype Aaee is crossed with a strain having the genotype AaEe. What will be the frequency of red offspring?

Answer 1

Wheat grains are red with the genotypes AaEe, AAEe, AaEE and AAEE.

Wheat grains are white with the genotype aaee.

Wheat grains are brown with genotypes Aaee, AAee, aaEe, aaEE.

The cross between a brown strain (Aaee) and a red strain (AaEe) results in the following offspring:

• possible gametes are Ae / ae and AE, Ae, aE, ae.
• possible offspring genotypes are AAEe, AAee, AaEe, Aaee, AaEe, Aaee, aaEe, aaee.
• the genotypes of red offspring are AAEe, AaEe, AaEe.
• the frequency of red offspring is 3/8 = 0.375 = 37.5%.

Answer: 37.5%