Here’s a breakdown of teh provided text, focusing on the key findings about the potato’s origin:
the Potato’s Origin: A Hybrid Story
Native to South America: The potato, a globally critically important crop, originated in South America.
A Long-Standing Mystery: Scientists were puzzled by the potato’s origin, as modern potato plants looked similar to a tuberless species called Etuberosum, but were genetically closer to tomatoes.
The DNA Paternity Test: A thorough study analyzed 101 genomes and 349 resequenced samples from cultivated potatoes and their 56 wild relatives.
The Hybrid Revelation: The analysis revealed that all potatoes carried genetic contributions from both Etuberosum and the tomato. This led to the conclusion that the potato is a hybrid offspring of these two species.
Parental Roles: The tomato acted as the maternal parent, and Etuberosum was the paternal parent.
Timeline of Origin:
Etuberosum and the tomato began diverging around 14 million years ago.
They hybridized approximately 5 million years after their divergence. The earliest tuber-bearing potato plants emerged around 9 million years ago.
The Mystery of the Tuber:
The Puzzle: While the potato is a hybrid,its parents (tomato and Etuberosum) do not develop tubers. The tomato lacks underground stems and tubers, and Etuberosum has underground stems but no swollen tubers.
The Bold Description: Genomic Rearrangement: The researchers proposed that the tuber is a product of genomic rearrangement that occurred during the recombination of genes after the hybridization. This accidental recombination created the tuber as a new organ.
Key Tuber Formation Genes:
SP6A gene: This “master switch” gene, responsible for initiating tuber formation, originated from the tomato parent.
IT1 gene: This gene, which controls the growth of underground stems that form tubers, came from the Etuberosum parent.
Both genes were essential for the hybrid offspring to produce tubers.
Advantages of the Tuber:
Genetic Diversity: The hybridization enriched the genetic diversity of the potato lineage.
Adaptability: The “mosaic” pattern of parental genetic contributions allows potatoes to adapt to diverse environments by selecting optimal gene sets under varying stresses.
Survival Advantage: Tubers store water and starch, helping potatoes survive drought and cold. They also facilitate reproduction without seeds or pollination, as new plants can grow from tuber buds. This gave potatoes a significant advantage in harsh environments, leading to an “explosion of new species.”
