Inhibitory Factor

What is Inhibitory Factor? – Definition

  • Involves two pairs of non-allelic genes
  • Affect the same character
  • One of the dominant genes inhibits or suppresses the expression of the other dominant gene.
  • Inhibiting gene has no visible effect
  • Inhibitory factor interaction is observed in plumage color of poultry

White leghorn’s white plumage is monogenic dominant over colored plumage.

White leghorn when crossed with white Wyandotte, F1 was white but segregation in F2 as 13 white: 3 colored. It is proved that, white leghorn contains gene C for colored plumage, but in addition it also contains gene I (inhibiting gene), which inhibits the colored expression.

So the genotype of pure breeding white leghorn must be CCII and that of Wyandotte’s ccii.

Cross between F1 F2
CCII X ccii
White leghorn X wyandotte
13 white : 3 colored

Inhibitory factor is one of the type of gene interaction, to know other types of gene interactions go to Types of Gene Interaction.