Origin of wild triploid potatoes (section Petota, Solanum L., Solanaceae) from Uruguay and Brazil
Allotriploid, autotriploid, cpDNA, ribosomal DNA, reticulate evolution
Tuber-bearing species of Solanum L. section Petota exhibit extensive genetic and cytotypic diversity, yet the origin of natural triploids remains poorly understood. Here, we investigated triploid formation in S. chacoense (2 EBN), S. commersonii (1 EBN), and S. malmeanum (1 EBN), species distributed across Brazil and Uruguay with different Endosperm Balance Number (EBN) values. Integrating plastid, nuclear, genomic, and cytogenetic data, we show that triploids have multiple independent origins, including inter- and intra-EBN allotriploids and autotriploids. Chloroplast data identified S. commersonii and S. malmeanum as frequent maternal parents, while nuclear and cytogenetic evidence revealed interspecific genomic contributions and introgression. These findings demonstrate that partial permeability of EBN-mediated reproductive barriers enables recurrent hybridization and independent triploid formation. Our results reveal that hybridization and EBN dynamics are key drivers of reticulate evolution and genetic diversification in wild potato species.