GENETICS QUESTION 1 One form of male sterility Ms in corn is

GENETICS QUESTION!!!!

1. One form of male sterility (Ms) in corn is maternally transmitted. Plants of a male sterile line crossed with normal pollen give male-sterile plants. In addition, some lines of corn are known to carry a dominant nuclear restorer allele (Rf-1) that restores pollen fertility in male sterile lines. Another dominant restorer (Rf-2) has been found on a different chromosome. Either or both of the restorer alleles will restore pollen fertility in male sterile lines.

If a male-sterile plant is crossed with pollen from a plant homozygous for Rf-1, what is the phenotype of the F1?

fertile females; sterile males

sterile females; fertile males

1/2 fertile females; 1/2 sterile females; 1/2 sterile males; 1/2 fertile males

fertile females; fertile males

sterile females; sterile males

2. One form of male sterility (Ms) in corn is maternally transmitted. Plants of a male sterile line crossed with normal pollen give male-sterile plants. In addition, some lines of corn are known to carry a dominant nuclear restorer allele (Rf-1) that restores pollen fertility in male sterile lines. Another dominant restorer (Rf-2) has been found on a different chromosome. Either or both of the restorer alleles will restore pollen fertility in male sterile lines.

A male-sterile plant is crossed with pollen from a plant homozygous for Rf-1. An F1 plant from this cross is used as the ovule donor, and crossed with pollen from a normal plant (rf-1/ rf-1). What phenotypes are produced by this cross?

fertile females; sterile males

sterile females; fertile males

fertile females; 1/2 fertile males; 1/2 sterile males

1/2 fertile females; 1/2 sterile females; 1/2 fertile males; 1/2 sterile males

fertile females; fertile males

Solution

1. MSt females x Rf/Rf males would generate all fertile Rf/+. Option d is the correct answer.

2. MSt females x +/+ males would generate 1/2 male sterile +/+ and 1/2 male fertile Rf/+. So the correct answer is option c.