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PLSC 210 - Horticulture Science
Fall Semester, 2010
Homework #1
Name____________________________
(Total 25 points, due: Friday, September 24)
Flower color and color pattern in genus Salpiglossis are controlled by two genes: R gene for red or yellow
color, D gene for solid or dilute color pattern. Red (R_) flower color is dominant to yellow (rr) flower
color, and solid color (D_) pattern is dominant to dilute (dd) color pattern. Using the examples given
below, fill in the genotype and phenotype of the seed parent (P1), and the genotypes, phenotypes, and
segregation ratios of the F2 progenies in the diagram.
1.
2.
3.
4.
Genotype
Phenotype
Genotype
Phenotype
Genotype
Phenotype
Genotype
Phenotype
R_D_ (RRDD, RRDd, or RrDd)
Solid, red
R_dd (RRdd, Rrdd)
Dilute, red
rrD- (rrDD, rrDd)
Solid, yellow
rrdd
Dilute, yellow
P1
P2
×
(A)
(B)
Phenotype
Genotype
Solid Yellow
(rrDD)
F1
Phenotype
Genotype
Solid Red
(RrDd)

F2
Phenotype
Genotype
Segregation ratio
(C)
(F)
(D)
(R_dd)
Solid Yellow
(G)
(E)
(H)
9
(I)
(J)
1
Figure 1. Inheritance of flower color and color pattern in F1 and F2 progenies of a cross between two homozygous
lines of Salpiglossis sinuata (velvet flower).
1. List all of the genotypes that could possibly be formed in the segregating population of the
self-pollinated progeny of RrDd. (5 points)
2. List all of the phenotypes that could possibly be obtained in the self-pollinated progeny of
RrDd. (5 points)
3. Show the phenotype and genotype of the seed (maternal) parent (P1) shown in Figure 1.
Phenotype
A _____________________________ (3 points)
Genotype
B ______________________________ (3 points)
4. Show the phenotypes, genotypes, and the segregation ratio of the F2 progeny in Figure 1.
Phenotypes
C _____________ D ____________
Genotypes:
F ______________ G _____________ H ______________ (3 points)
Segregation ratio
I _______________ J _____________ (3 points)
2
E ______________ (3 points)