Can a cross between a homozygous red flowering plant and a homozygous white flowering plant produce a pink flowering plant?
1 Answer
Yes, if the type of inheritance is incomplete dominance, the heterozygous genotype Rr will be a blend of the R and r alleles.
Assuming that R represents the red color allele for petal color, and r represents the white color allele, the homozygous RR genotype will produce the red color phenotype, the heterozygous Rr genotype will produce the pink color phenotype, and the homozygous rr genotype will produce the white color phenotype. Neither the red allele nor the white allele is dominant, and the Rr genotype produces a blended color. This is the type of inheritance governing the red, pink, and white flower color in snap dragons and some other flowers like tulips.
There are many ways to represent the alleles and genotypes for incomplete dominance between homozygous red and homozygous white flowers, such as snap dragons. They are:
Red, Pink, White Genotypes:
RR, Rr, rr
RR, RW, WW
rr, rw, ww
I personally prefer not to use a lowercase letter to represent an allele in incomplete dominance, because of the fact that a lowercase allele so often represents a recessive allele. However, in incomplete dominance, neither allele is dominant or recessive.
