Explain co-dominance with example.

Codominance : It is the phenomenon of two alleles lacking dominant-recessive relationship and both expressing themselves in the organism
Eg: (i) When a cross is made in lentil (Lens culinaris) between pure breeding spotted and dotted phenotypes.
(ii) The F₁ heterozygotes resulted with both spotted and dotted phenotypes.
(iii) On self-pollination of F₁ plants, the F₂ plants showed the phenotypes as 1spotted: 2 spotted and dotted:1 dotted.
(iv) The heterozygotes differ from both the homozygotes parents w.r.t. both phenotype and genotype and hence both phenotypic and genotypic ratio is same 1:2:1.