5. (3 pt). A corn plant of genotype mtS rfrf is used as a tester to identify the

Question

5. (3 pt). A corn plant of genotype mtS rfrf is used as a tester to identify the genotype of the following corn plants. Each plant (the male) was mated to the tester (the female) and several testcross plants (Fi) of each mating were grown and evaluated to see if they were either all pollen-fertile, all pollen-sterile or segregating for pollen-sterile and pollen fertile types. The phenotypic information of the testcross progeny should allow you to determine, in some cases, the nuclear (Rfrf, Rfrf, rfrf or, not sure) and mitochondrial genotypes (mtF, or mtS, or not sure) of each plant mated to the tester. Write the genotype of each plant in the open squares in the table:

Explanation / Answer

The female gametes contribute the mitochondria and chloroplasts. In plants who have sterile pollen, the mitochondrial genotype is mtS, whereas, plants with fertile pollen have mitochondrial genotype is mtF.

For plants with mtS, the phenotype can be either sterile/ fertile pollen depending on the nuclear genotype, whereas, for plants with mtF, the phenotype will always be fertile.

Rf is considered as the dominant nuclear gene, which restores the fertility in mtS plants, whereas rf is the recessive nuclear gene and cannot restore fertility.

Based on the above points and the given information the cross between the male and female will be

mtFRfRf X mtSrfrf

which means that the nuclear genotypes could be RfRf, rfrf or Rfrf

and mitochondrial genotype can be either mtF or mtS

Hence, for the given conditions

Nuclear

Mitochondrial

All pollens fertile

RfRf

mtF

1 pollen sterile, 1 pollen fertile

Rfrf

mtS

All pollen sterile

Rfrf

mtS

Nuclear

Mitochondrial

All pollens fertile

RfRf

mtF

1 pollen sterile, 1 pollen fertile

Rfrf

mtS

All pollen sterile

Rfrf

mtS

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.