In a cross of four O'clock plants in the progeny half pink flower plant and halt white flower plants are produced, the genotype of plants crossed is

Options

A. `R^(1)R^(1)xxR^(2)R^(2)`
B. `R^(1)R^(2)xxR^(1)R^(2)`
C. `R^(1)R^(2)xxR^(2)R^(2)`
D. `R^(1)R^(1)xxR^(1)R^(1)`

Answer

To solve the question regarding the cross of four o'clock plants that results in half pink flower plants and half white flower plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Flower Color Genetics**:
- In four o'clock plants, flower color is determined by two alleles:
- R1 (red)
- R2 (white)
- The genotype R1R1 produces red flowers, R2R2 produces white flowers, and R1R2 produces pink flowers due to incomplete dominance.

2. **Analyze the Progeny Ratio**:
- The question states that the progeny consists of half pink and half white flowers. This indicates a 1:1 ratio of pink to white flowers.

3. **Determine Possible Genotypes of Parents**:
- To achieve a 1:1 ratio of pink to white flowers, one parent must contribute the R1 allele (pink) and the other must contribute the R2 allele (white).
- Therefore, the possible parental genotypes could be:
- Parent 1: R1R2 (pink flower)
- Parent 2: R2R2 (white flower)

4. **Perform the Cross**:
- When we cross R1R2 (pink) with R2R2 (white):
- Gametes from R1R2: R1 and R2
- Gametes from R2R2: R2 and R2
- The resulting offspring genotypes will be:
- R1R2 (pink)
- R2R2 (white)

5. **Count the Offspring**:
- The offspring will be:
- 50% R1R2 (pink)
- 50% R2R2 (white)
- This matches the given condition of half pink and half white flowers.

6. **Conclusion**:
- The genotypes of the plants crossed are R1R2 (pink) and R2R2 (white).

### Final Answer:
The genotype of the plants crossed is R1R2 (pink flower) and R2R2 (white flower).

---