Seeds from a diploid true breeding plant that produces purple flowers were mutagenized. Below are the genotypes and phenotypes of plants generated from this mutagenesis experiment. Assume that the wild-type alleles (uppercase) are dominant to mutant alleles (lower case) and the two genes are not linked. Genotype Flower color A_B_ Purple aaB_ Orange

The Answer is B

Explanation

abb genotype produces brown pigment. In this case mutant alleles are present at both the locus and brown pigment is produced which suggest the brown pigment is the precursor for the pathway and is present even when both mutant alleles are present.

aaB_ genotype produces orange pigment which suggest that B allele is responsible for conversion of brown pigment to orange pigment. This is also supported by the genotype A_bb which produces brown pigment because wildtype B allele is not present. A allele cannot convert Brown to orange, therefore flower colour is brown.

A_B_genotype produces purple pigment which suggest both A and B allele are responsible for conversion of brown pigment to purple pigment