The genetics of petal color in spider flower (Cleome hasslerana L.) have been described. Three genes are involved, each of which has two alleles. The W gene controls color: WWand Ww plants have colored flowers, but the petals of homozygous ww plants are white, regardless of the other genes' alleles. The R gene controls which pigment is produced: R– plants produce violet- or lilac-colored flowers, and rr plants produced red or pink flowers. The third gene, I controls pigment intensity: I– plants have dilute petal color (lilac or pink), whereas recessive homozygotes (ii) have intense color (violet or red). (Note that dilute flower color is dominant to intense color, which is perhaps unexpected: dominance/recessivity does not correlate to strength or intensity of phenotype!)
How many different genotypes are possible in spider flower?
Of those genotypes, how many result in plants with white flowers? Violet? Lilac? Red? Pink?
You have a spider flower of unknown genotype, but it has white flowers. Describe the result of doing a standard test cross with it.
What genotype would you want to use to answer part c?
What is the phenotype of a WwRrii plant?
What are the expected progeny (phenotypes and ratios) if you self-cross this plant?
What is this ratio an example of?