Highlights

• The potato lineage is of ancient homoploid hybrid origin

• Alternate inheritance of highly divergent parental genes contributed to tuberization

• Hybridization and tuberization triggered species radiation and niche expansion

Interspecific hybridization may trigger species radiation by creating allele combinations and traits. Cultivated potato and its 107 wild relatives from the Petota lineage all share the distinctive trait of underground tubers, but the underlying mechanisms for tuberization and its relationship to extensive species diversification remain unclear.

Through analyses of 128 genomes, including 88 haplotype-resolved genomes, we revealed that Petota is of ancient hybrid origin, with all members exhibiting stable mixed genomic ancestry, derived from the Etuberosum and Tomato lineages ca. 8–9 million years ago.