Solutions For An Introduction to Genetic Analysis Chapter 3 Problem 44P

7177-3-44P AID: 2975 | 21/03/2013

The variegated plant can be due to either a chloroplast mutation or a dominant nuclear mutation.

Since chloroplast mutations are maternally inherited, we can check whether the phenotype of the progeny is same as the phenotype of the mother. The flowers on the white branches are tested with pollen from green-branch flowers, white-branch flowers and variegated-branch flowers. If the seeds produced give rise to white plants irrespective of the source of pollen then this trait is due to a chloroplast mutation.

To check whether a dominant nuclear mutation is responsible for the variegation seen, we need to cross the flowers present on white branches with flowers present on green branches. The progeny will help us know whether the mutation is heterozygous or homozygous. If half the progeny are white and half are green, then the dominant mutation is heterozygous. If all the progeny is white then the dominant mutation is homozygous.