Say a farmer was selling decorative flowers and grew his own flowers to sell. He noticed that customers mostly wanted pink flowers. Thus to maximise his profit, the farmer would be selling pink flowers. However, he only has red and white flowers available. How would he grown flowers with pink petals?
Let’s assume that when both red and white traits are dominantly expressed on an allele, it mixes and forms a PINK flower. This special phenomenon is called codominance – where both alleles are equally strong and neither are masked by the other, thus expressing both in the resultant phenotype. If ‘W’ means dominant white and ‘R’ means dominant red – to express pink the genotype must be ‘WR’.
The farmer would have to manipulate the artificial pollination of his flowers to grow pink flowers. To ensure he will gain pink flowers after breeding, he will need to breed a homozygous red flower and a homozygous white flower. This is allow for codominance to occur, producing pink flowers. This could be his following method:
- Produce homozygous red flower (this will be the first parent)
| R | r | |
| R | RR | rR |
| r | Rr | rr |
25 % chance of receiving ‘RR’, if successful that flower can be used as a parent to produce pink flowers.
Any genotype with recessive alleles (e.g Rr, rR, rr) cannot be used as it wouldn’t allow for codominance.
- Produce homozygous white flower (second parent)
| W | w | |
| W | WW | Ww |
| w | wW | ww |
25 % chance of receiving ‘WW’, if successful that flower can be used as a parent to produce pink flowers
Any genotype with recessive alleles (e.g Ww, wW, ww) cannot be used as it wouldn’t allow for codominance.
| R | R | |
| W | RW | RW |
| W | RW | RW |
Outcome: In the end, the farmer will have a 100% chance of growing pink flowers through breeding homozygous red and homozygous white flowers together. Therefore, the farmer will be able to maximise his profit through selling mostly pink flowers!
Artificial Pollination 