Question

You continue your analysis by crossing the aberdeen white and victoria white lines. this time you count the actual numbers of progeny in the two f2 phenotypic classes. cross between aberdeen white and victoria white you also self several wild-type plants from the f2 and determine that some of them are pure-breeding. what can you conclude from these results?

Answer 1

1. Aberdeen white and victoria white are allels of different loci. That's why they are expressing two different shades. 

2. The pure-breding progeny wild-type progeny in the F2 are the result of "recessive epistasis". Both gene pairs exhibit complete dominance, but a recessive homozygote of either gene pair is epistatic to the other gene (supresses its expression). Actually this is a type of duplicate recessive inheritance pattern, in which the progeney are produced in 9: 7 ratio.  

3. The F2 ratio is approximately 9: 7 (181/ 139).  

4. The F2 ratio results from complementary gene action. The presence of any homozygous recessive allele is epstatic to the other gene. The genotypes aaBB, AAbb, aabB, Aabb produce the same phenotypes.