Published in Cell, the study reveals that this interbreeding introduced critical genetic material enabling the formation of tubers-specialized underground structures for nutrient storage seen in potatoes, yams, and taros.
"Our findings show how a hybridization event between species can spark the evolution of new traits, allowing even more species to emerge," said corresponding author Sanwen Huang of the Chinese Academy of Agricultural Sciences. "We've finally solved the mystery of where potatoes came from."
Despite their similarity to tuberless Etuberosum plants native to Chile, potatoes are genetically more aligned with tomatoes. This paradox led researchers to conduct an extensive genomic analysis of 450 cultivated potato varieties and 56 wild potato species.
"Wild potatoes are very difficult to sample, so this dataset represents the most comprehensive collection of wild potato genomic data ever analyzed," said first author Zhiyang Zhang of the Agricultural Genomics Institute at Shenzhen.
The findings revealed that all potato species possess a consistent genomic blend from both tomato and Etuberosum ancestors. These groups diverged from a shared ancestor about 14 million years ago but retained compatibility long enough to interbreed around 9 million years ago, giving rise to the first tuber-producing plants.
Crucially, the researchers identified the origin of two key genes responsible for tuber development. The SP6A gene-derived from the tomato lineage-acts as a switch to initiate tuber formation. The IT1 gene-traced to Etuberosum-regulates underground stem growth. Without contributions from both genes, tubers would not have evolved.
This pivotal development occurred during a period of environmental upheaval as the Andes mountains rose dramatically, creating diverse and challenging new habitats. Tubers enabled early potatoes to store energy and survive seasonal stress, promoting their adaptation and spread.
The ability to reproduce via sprouting tubers, rather than relying solely on seeds or pollination, further boosted their ecological success across grasslands and alpine zones throughout Central and South America.
"Evolving a tuber gave potatoes a huge advantage in harsh environments, fueling an explosion of new species and contributing to the rich diversity of potatoes we see and rely on today," Huang noted.
Research Report:Ancient hybridization underlies tuberization and radiation of the potato lineage
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Chinese Academy of Agricultural Sciences
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