In a certain species of flowering plants with a diploid genome, four enzymes are
ID: 65632 • Letter: I
Question
In a certain species of flowering plants with a diploid genome, four enzymes are involved in the generation of flower color. The genes encoding these four enzymes are on different chromosomes. The biochemical pathway involved is as follows: the figure shows that either of two different enzymes is sufficient to convert a blue pigment into a purple pigment. A true-breeding green-flowered plant is mated with a true-breeding blue-flowered plant. All of the plants in the resultant F| generation have purple flowers. F_1 plants are allowed to self-fertilize, yielding an F_2 generation. Show genotypes for P. F_1 and F_2 plants, and indicate which genes specify which biochemical ,steps. Determine the fraction of F_2 plants with the following phenotypes: white flowers, green flowers, blue flowers, and purple flowers. Assume the green-flowered parent is mutant in only a single step of the Hr pathway.Explanation / Answer
True breeding between blue and green flowered plants is,
GG* BB = 100% GB (Purple colored).
Cross between F1 generation is, GB* GB = GG, GB, GB, BB.
True breeding for GG -------> Green
True breeding for BB --------> Blue
GB codes for ------------------> Purple
The phenotypic ratio of Green to purple to blue is, 1: 2: 1.