If doubled haploids are produced from the pollen of a plant with the genotype Aa, which of the following lists all the possible doubled haploid genotypes that will be produced?

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BlackTom AI · Accepted Answer

To tackle this question, we first recall what a doubled haploid is: a line that originates from a haploid complement and then has its chromosome number doubled to become diploid, retaining homozygosity at each locus.
Option 1: 'AA, Aa, aa' suggests three possible outcomes, including the heterozygous Aa genotype. Since the starting plant is Aa, the pollen (gamete) can be either A or a, both of which are haploid. After doubling, these haploids become homozygous: AA or aa. The heterozygous Aa cannot occur in a doubled haploid, so this option is incorrect.
Option 2: 'A, a' lists gamete genotypes (haploid) rather than the resulting diploid doubled haploid genotypes. The question asks for the doubled haploid genotypes, not the gametes, so this is not the correct format or content.
Option 3: 'Aa' presents a heterozygous genotype. As explained, a doubled haploid is inherently homozygous at the locus in question, because it originates from a single haploid chromosome set that is then duplicated. Therefore Aa is impossible for a doubled haploid and this option is incorrect.
Option 4: 'AA, aa' exactly matches the two homozygous outcomes produced after doubling the haploid gametes from an Aa parent. When the pollen contributes P = A or P = a, doubling yields AA or aa, respectively. This aligns with the fundamental genetics of haploid doubling and homozygosity.
In summary, the only option that lists the complete and correct set of doubled haploid genotypes obtainable from an Aa parent is AA and aa, making this the correct choice.

AGRI10051_2025_SM2 Supplementary or Special Exam: Genetics for Agriculture (AGRI10051_2025_SM2)- Requires Respondus LockDown Browser

If doubled haploids are produced from the pollen of a plant with the genotype Aa, which of the following lists all the possible doubled haploid genotypes that will be produced?

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