Dr. Ara B. Dopsis has an idea he thinks will be a boon to agriculture. He wants to create the 'pomato,' a hybrid between a tomato (Lycopersicon esculentum) that has 12 chromosomes and a potato (Solanum tuberosum) that has 48 chromosomes. Dr. Dopsis is hoping his new pomato will have tuber growth like a potato and the fruit production of a tomato. He joins a haploid gamete from each species to form a hybrid and then induces doubling of chromosome number. Will this hybrid be infertile?

Verified step by step guidance

1. Determine the chromosome number of the haploid gametes from each species. The tomato (Lycopersicon esculentum) has 12 chromosomes in its diploid state, so its haploid gamete will have 6 chromosomes. The potato (Solanum tuberosum) has 48 chromosomes in its diploid state, so its haploid gamete will have 24 chromosomes.
2. Combine the haploid gametes from the tomato and potato to form the hybrid. The hybrid will initially have 6 chromosomes from the tomato and 24 chromosomes from the potato, resulting in a total of 30 chromosomes.
3. Induce chromosome doubling in the hybrid. Doubling the chromosome number will result in 60 chromosomes in total (2 × 30). This process creates a tetraploid organism, where each chromosome now has a homologous pair.
4. Assess the fertility of the hybrid. Fertility in hybrids depends on whether homologous chromosomes can pair during meiosis. In this case, the hybrid has chromosomes from two different species, which are unlikely to be homologous. This lack of homologous pairing will prevent proper meiosis, leading to infertility.
5. Conclude that the hybrid pomato will likely be infertile because the chromosomes from the tomato and potato are not homologous, preventing successful gamete formation during meiosis.

Key Concepts

Hybridization

Hybridization is the process of combining different varieties or species to create a new organism with traits from both parents. In this case, Dr. Dopsis aims to hybridize a tomato and a potato, which belong to different genera. Successful hybridization can lead to new agricultural varieties, but it often faces challenges, especially when the parent species have significantly different chromosome numbers.

Chromosome Doubling

Chromosome doubling, or polyploidy, involves increasing the number of chromosome sets in an organism. This process can help stabilize hybrids by making their chromosome number more compatible, potentially allowing for successful reproduction. In the context of the pomato, inducing chromosome doubling after hybridization may help overcome fertility issues that arise from the initial differences in chromosome numbers between the tomato and potato.

Fertility in Hybrids

Fertility in hybrids is often influenced by the genetic compatibility of the parent species. When two species with different chromosome numbers are hybridized, the resulting offspring may have difficulty pairing chromosomes during meiosis, leading to infertility. In the case of the pomato, the initial hybrid may be infertile due to the disparity in chromosome numbers, but chromosome doubling could potentially restore fertility by creating a more balanced genetic structure.