One form of male sterility (Ms) in corn is maternally transmitted. Plants of a m

Question

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

Explanation / Answer

Let us summarize the data given in the question:

1. Male sterility (Ms) in corn is maternally transmitted. So, the phenotype is X-linked

2. Male sterile line when crossed with normal pollen gives male sterile plants.

3. Rf-1 and Rf-2 dominant allele restore pollen fertility in male sterile lines.

Before solving this problem let us name the alleles with different alphabets for proper understanding.

Let the alleles for male-sterile lines be X'X', Where X' represents X-linked inheritance

Let the alleles for nuclear restorer line be XRY

The cross between male sterile plant and plant homozygous for Rf-1 will be as follows:

X'X' x XRY

X'XR , X'XR , X'Y, X'Y

So, two fertile females and two sterile males are obtained.

Thus, the correct answer to this question will be fertile females and sterile males

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