In a plant species, the following pathways contribute to seed color. The wild type phenotype of seed color is red.

• A recessive mutation of gene A leads to a white color pigment.

• A recessive mutation of gene B leads to a transparent outer layer, and the color of the seed is based on the color of the endosperm.

• The two genes are present on two different chromosomes.

• Often, a yellow or white colored seed has red spots.

Based on the above information, the following statements were made:

• A. The probability of getting red-colored seeds from a dihybrid cross involving two heterozygous mutants is 9/16.

• B. The mutation in gene B could have been caused by a transposable element.

• C. A plant producing red seeds would breed true for the seed color.

Which  one of the following options represents a combination of all correct statements?

Correct option is B

 Explanation:

• Wild-Type Phenotype: The wild type of seed color is red, which indicates the presence of both yellow and red pigments due to the functioning of genes A and B.

• Gene A: A recessive mutation in gene A leads to a white color pigment. Thus, the wild-type A allele (A) is required for yellow pigment deposition in the endosperm.

• Gene B: A recessive mutation in gene B results in a transparent outer layer, indicating that the wild-type B allele (B) is necessary for red pigment deposition in the outer layer.

• Seed Color Determination: The final seed color is dependent on the color of the endosperm, which is determined by the activity of gene A and gene B.

A. The probability of getting red-colored seeds from a dihybrid cross involving two heterozygous mutants is 9/16.

• This statement is incorrect. The seed color in this case depends on the presence of at least one dominant allele from both genes A and B for red seeds. The calculation for a dihybrid cross involving complementary or supplementary genes does not lead to a straightforward 9/16 probability.

B.The mutation in gene B could have been caused by a transposable element.

• Correct. Transposable elements (TEs) can cause mutations in the genome, including insertions that can disrupt normal gene function. Therefore, a mutation in gene B could have been caused by such an element.

C. A plant producing red seeds would breed true for the seed color.

• This statement is incorrect. For a plant producing red seeds (A--), it can either be homozygous dominant (AABB) or heterozygous (AaBb). If the plant is heterozygous, it will not breed true because it can produce gametes with both dominant and recessive alleles, leading to a variety of offspring colors. Therefore, unless the plant is homozygous, it won't breed true.