Question

In Antirrhinum, two plants with pink flowers were hybridized. The F${}_1$ plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridization. Red flower colour is determined by RR, and white by rr genes?

• A. rr
• B. RR
• C. Rr
• D. rrrR

Answer 1

The correct option is C Rr

Red (RR) crossed with recessive white (rr) ------> F${}_1$ generation: Rr (Pink flowers)
Selfing of F${}_1$ : Rr x Rr -----> RR (red), Rr (pink), Rr (pink), and rr (white)
This is an indication of incomplete dominance. Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a third phenotype in which the expresses physical trait is a combination of the dominant and recessive phenotypes. The ratio is thus, 1:2:1.