Complementary genes.pptx

Bateson & Punnet in 1905 studied the inheritance of flower colour in Sweet Peas . When two white-flowered varieties of sweet pea with different genotypes CCpp and ccPP were crossed offspring produced in the F1 generation were purple flowered and In the F2 generation, both and white purple  flowered plants were produced in a phenotypic ratio of 9 purple:7 white.

1. Complementary Genes

Complementary genes are a kind of gene interaction in which two
dominant non-allelic genes interact together to produce a specific
phenotype that neither can produce independently.

Despite being dominant, each gene within a complementary pair
cannot generate independent phenotypes.

Bateson & Punnet in 1905 studied the inheritance of flower colour in
Sweet Peas (Lathyrus odoratus). He crossed two white-flowered
varieties of sweet pea plants with different genotypes CCpp and ccPP.

Each variety bred true and produced white flowers in successive
generations.

2. Parents - White Flowered X White Flowered
CCpp

Genotype - CCpp

Gametes

F, Generation - White Flowered (100%)
Genotype - CCpp

3. Parents - White Flowered X White Flowered
Genotype - ccPP ccPP

Gametes

F, Generation - White Flowered (100%)
Genotype - ccPP

4. When two white-flowered varieties of sweet pea with different
genotypes CCpp and ccPP were crossed, the offspring produced in the
F, generation were purple flowered (genotype — CcPp)

When F, purple flowered plants were selfed

In the F2 generation, both and white purple flowered plants were
produced in a phenotypic ratio of 9 purple:7 white.

The purple colour is created by the interaction of two non allelic genes
that are in a dominant state.

The purple colour of the flower is due to the presence of a pigment
called anthocyanin.

5. Parents - White Flowered x White Flowered
Genotype - CCpp ccPP

Gametes

F, Generation - Purple Flowered x Selfed
Genotype - CcPp

F, Gametes

6. F2 - Generation

CcPp

ccpp

CcPP

ccP;

CCPP

SE
1S)

Phenotypic Ratio 9: 7 Purple 9 : White 7

7. Anthocyanin pigment: is produced by the interaction of two non allelic.
dominant ana rec genes Cand P.

A dominant gene C is responsible for the production of chromogen.
When this gene is recessive (c) the chromogen cannot be produced.

Similarly another dominant gene P is responsible for the production of
an enzyme, which converts the chromogen into anthocyanin pigment.
when this gene is recessive (p) the enzyme which converts the
chromogen into anthocyanin cannot be produced and thus chromogen.
cannot be converted into anthocyanin pigment.

If a plant possesses both dominant complementary genes C and P, it
produced anthocyanin pigment and thus flowers were purple. - tis

In the absence of either complementary genes C or P the flowers were
white.

8. If Dominant Gene C alone is present (In the absence of its
complementary gene P) flower colour will be White (CCpp < or Ccpp).

Dominant Gene C produces precursor for Anthocyanin pigment
(Chromogen) and the recessive complementary fone m cannot
convert precursor into Anthocyanin Pigment. - :

If Dominant Gene P alone is present (In the absence complementary
gene C) flower colour will be White etre or cere)

If Damian cata (c) i is Abeba its recessive (jeter (c) cannot rauch
precursor for Anthocyanin (Chromogen). In the absence of precursor
for Anthocyanin, its complement dominant gene P cannot synthesize
Anthocyanin pigment.

The purple colour is created by the interaction of two non allelic genes
that are in a dominant state.