3. Complementary gene interaction (9:7)
• Here two or more independent genes present on same loci or different
work together to create a specific phenotype.
• They are called complementary because they cannot express without
each other.
• Bateson and Punnett crossed Lathyrus odoratus. The white flowers of
Lathyrus is represented by both CCpp and ccPP genes. When they were
crossed, in F1 generation (CcPp) all plants produced purple flowers.
• The F2 generation was raised and both purple and white flowers were
obtained at a ratio of 9:7.
13. • When recessive alleles at one locus mask the expression
of both (dominant and recessive) alleles at another
locus, it is known as recessive epistasis.
• The modified phenotypic ratio is 9:3:4.
