🌱 Potatoes Evolved from a Tomato Ancestor
Scientists have just solved a mystery that has puzzled biologists for years: how the potato developed tubers.
Above ground, today's potato plant is visually similar to a wild species from Chile called Solanum etuberosum. But here's the catch: those wild relatives don't grow tubers. Until recently, no one could explain how potato tubers first evolved.
Researchers analyzed the genomes of more than 450 cultivated potato varieties and 56 samples of wild species, comparing their DNA to that of other plants in the nightshade family. Genomic analysis revealed a surprising result: the potato's DNA is a hybrid mosaic, with approximately 50% of its genes derived from the tomato lineage and 50% from Etuberosum.
Neither of these parent plants forms tubers on its own, but each contributed something essential. Potatoes inherited from the tomato side the SP6A gene, which sends the signal to "form tubers," but tomatoes lack the underground structures needed to grow them. From Etuberosum, potatoes inherited the IT1 gene, which builds underground stems called stolons—but without SP6A, these don't develop into tubers.
This ancient cross happened around 8 to 9 million years ago, during the formation of the Andes Mountains. As the mountain range rose, the regional climate became colder and drier.
In these tough conditions, underground tubers that stored food and water gave the hybrid plant a huge advantage. It didn't just survive—it quickly spread and thrived in new environments.
