Question

In the tubular flowers of foxgloves, wild-type coloration is red while a mutation called white produces white flowers. Another mutation, called peloria, causes the flowers at the apex of the stem to be huge. Yet another mutation, called dwarf, affects stem length. You crossed a red-flowered plant (gene symbol, r) to a plant that is dwarf (gene symbol, d) and peloria (gene symbol, p). All of the F1 plants are tall with red, normal stem flowers. You cross an F1 plant back to the dwarf and peloria parent, and you see the 543 progeny shown in the chart.

Dwarf, peloria stem, white 172

Tall, peloria stem, red 56

White, Tall, normal term 48

Red, dwarf, normal stem 6

Red, dwarf, peloria stem 43

White, tall, peloria stem 5

Red, tall, normal stem 162

Dwarf, normal stem, white 51

1) Which alleles are dominant?

2) What were the genotypes of the parents in the original cross?

3) Draw a map showing the linkage relationships of these three loci(R, D, P)

Answer 1

In the F₁ generation , each individual receives one dominant type allele and one recessive allele. Thus all individuals shows dominant phenotype. Here ,dominant phenotype is Tall, Red flowers and normal stem.

2.

The highest number of progeny in F₂ generation represents the parental genotype. They are the Non Crossover individuals.

So genotypes of the parents in original cross is

DD PP RR & dd pp rr

3.