Reflection on Phenotypic Proportions in Plant Genetics

What proportion of the F2 plants will resemble the F1 plants in phenotype?

If a true-breeding white, tall, normal-flowered plant is crossed to a true-breeding red, dwarf, symmetrical flowered one, what proportion of the F2 plants will resemble the F1 plants in phenotype?

Answer:

9/32 Pink, Tall, and Normal individuals Rr Tt Nn

In snapdragons, the red flower color is incompletely dominant to white, with the heterozygote being pink. Normal flowers are completely dominant to symmetrical flowers, and tallness is completely dominant to dwarfness. The three gene pairs segregate independently.

The F1 generation will have pink flowers as a result of the incomplete dominance between red and white flower colors. In the F2 generation, the genotypic ratio will be 1 CRCR:2 CRCW:1 CW CW, and the phenotypic ratio will be 1:2:1 for red:pink:white.

When the F1 generation is self-crossed to produce F2 progeny, we must calculate the phenotypic ratio for each trait separately due to independent assortment. For flower color, we expect a 1:2:1 phenotypic ratio (red:pink:white), whereas for the other traits, we observe a traditional 3:1 Mendelian ratio for dominant to recessive phenotypes because these traits follow complete dominance.

The proportion of F2 plants that will resemble the F1 phenotype can be calculated by multiplying the probabilities of each individual trait expression.