Mendelian ratios are modified in crosses involving autotetraploids. Assume that one plant expresses the dominant trait green seeds and is homozygous (WWWW). This plant is crossed to one with white seeds that is also homozygous (wwww). If only one dominant allele is sufficient to produce green seeds, predict the F₁ and F₂ results of such a cross. Assume that synapsis between chromosome pairs is random during meiosis.

Key Concepts

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations based on the principles established by Gregor Mendel. It includes concepts such as dominant and recessive alleles, genotype, and phenotype. In this context, the dominant allele for green seeds (W) masks the expression of the recessive allele for white seeds (w), leading to predictable ratios in offspring based on parental genotypes.

Autotetraploidy

Autotetraploidy refers to a condition where an organism has four sets of chromosomes, resulting from the duplication of its diploid genome. This can complicate inheritance patterns, as the presence of multiple alleles can lead to modified Mendelian ratios. In the given cross, the autotetraploid nature of the plants affects how alleles segregate during gamete formation and ultimately influences the phenotypic ratios in the offspring.

F₁ and F₂ Generations

The F₁ generation is the first filial generation resulting from a cross between two parental genotypes, while the F₂ generation is produced by interbreeding the F₁ individuals. In this scenario, the F₁ generation will all express the dominant green seed trait due to the presence of at least one dominant allele. The F₂ generation will exhibit a phenotypic ratio that reflects the modified inheritance patterns due to autotetraploidy, which can deviate from the classic 3:1 ratio seen in diploid organisms.