Answer to Question #349321 in Genetics for lisa

Question

Three gene pairs located on separate autosomes determine flower color and shape as well as plant height. The first pair exhibits incomplete dominance, where the color can be red, pink, (the heterozygote), or white. The second pair leads to personate (dominant) or peloric (recessive) flower shape, while the third gene pair produces either the dominant tall trait or the recessive dwarf trait. Homozygous plants that are red, personate, and tall are crossed to those that are white, peloric, and dwarf. Determine the F1 genotype(s) and phenotype(s). If the F1 plants are interbred, what proportion of the offspring will exhibit the same phenotype as the F1 plants?

Answer 1

Let the following genes be responsible for different traits:

• A - red color (incomplete dominance, in a heterozygous state - pink color);
• a - white color;
• B - personate flower shape;
• b - peloric flower shape;
• C - tall trait;
• c - dwarf trait.

According to the information provided above, we will make the following trihybrid cross:

P: AABBCC (red, personate, tall) × aabbcc (white, peloric, dwarf)

↓

F1: 64 AaBbCc (pink, personate, tall)

The cross of two plants from F1 will give the following result:

AaBbCc (pink, personate, tall) × AaBbCc (pink, personate, tall)

↓

Based on the Punnett square, only 18 offspring (highlighted in grey) have the same phenotype as the F1 plants. Based on the total number of offsprings of 64, the percentage of pink, personate and tall offspring will be:

(18*100%)/64 ≈ 28%.