Solutions For An Introduction to Genetic Analysis Chapter 10 Problem 34P

Transgenic tobacco plants are obtained from the vector Ti (tumour inducing) plasmid. The plasmid is designed to insert the gene of interest and the kanamycin resistance gene. The chromosomal insertion is followed by testing the progeny, for kanamycin resistance gene.

The plant 1, displays the usual inheritance, for a dominant gene, which is heterozygous. If kanamycin resistant is dominant to kanamycin sensitivity, the cross can be resulted as:

kan ^R / kan ^S × kan^S / kan^S

1/2 kan^R / kan^S

1/2 kan^S / kan^S

This would recommend that the gene of interest is possibly introduced once into the genome.

The plant 2, shows 3:1 ratio in the progeny of the back cross, which indicates that there have been two unlinked incorporations of kan^R gene and most probably the gene of interest too.

kan ^R1 / kan^S1; kan^R2 / kan^S2 × kan^S1 /kan^S1; kan^S2 / kan^S2

1/4 kan^R1 / kan^S1; kan^R2 / kan^S2

1/4 kan^R1 / kan^S1; kan^S2 / kan^S2

1/4 kan^S1 / kan^S1; kan^R2 / kan^S2

1/4 kan^S1 / kan^S1; kan^S2 / kan^S2