Suppose that a true breeding tall white strain is crossed to

Suppose that a true breeding tall white strain is crossed to a true breeding dwarf red strain. If the F1 generation is then self-crossed, what phenotypes will be produced in the F2 generation and in what portions are they expected?

In the snapdragons, a flowering plant, the trait of tall (Tis dominant to dwarf Flower color is controlled by a gene with two alleles, R for red and R for white and these two alleles have an incomplete dominance relationship so that the heterozygote is pink Suppose that a true breeding tall white strain is crossed to a true breeding dwarf red strai n. If the F1 generation is then self-crossed, what phenotypes will be produced in the F2 generation and in what portions are they expected? Use the forked line method the find the answer.

Solution

Answer:

P1 =TTR2R2 x ttR1R1

F1 = TtR1R2 (tall pink)

F2 = F1 x F1

TR1

TR2

tR1

tR2

TR1

TTR1R1 (Tall red)

TTR1R2 (Tall pink)

TtR1R1 (Tall red)

TtR1R2 (Tall pink)

TR2

TTR1R2 (Tall pink)

TTR2R2 (Tall white)

TtR1R2 (Tall pink)

TtR2R2 (Tall white)

tR1

TtR1R1 (Tall red)

TtR1R2 (Tall pink)

ttR1R1 (dwarf red)

ttR1R2 (dwarf pink)

tR2

TtR1R2 (Tall pink)

TtR2R2 (tall white)

ttR1R2 (dwarf pink)

ttR2R2 (dwarf white)

	TR1	TR2	tR1	tR2
TR1	TTR1R1 (Tall red)	TTR1R2 (Tall pink)	TtR1R1 (Tall red)	TtR1R2 (Tall pink)
TR2	TTR1R2 (Tall pink)	TTR2R2 (Tall white)	TtR1R2 (Tall pink)	TtR2R2 (Tall white)
tR1	TtR1R1 (Tall red)	TtR1R2 (Tall pink)	ttR1R1 (dwarf red)	ttR1R2 (dwarf pink)
tR2	TtR1R2 (Tall pink)	TtR2R2 (tall white)	ttR1R2 (dwarf pink)	ttR2R2 (dwarf white)