Assigning Species Names to Ambiguous Populations in the US Potato Genebank

The US Potato Genebank (USPG) has germplasm of a single crop, about 6,500 samples of tuber-bearing Solanum species. Despite many years of vigorous taxonomic efforts, 80 populations at USPG were indexed only as “Solanum spp.” as of 2022, indicating that the proper species name was unknown. DNA markers were used to match these populations to an array of 77 standard species. Populations were also grown to maturity in the field and determined using the latest taxonomic keys. Species determinations based on the closest DNA match were highly supported by existing records for ploidy and country of origin but only modestly by taxonomic keys (36%). For some unknown populations, a clear match to a standard species name could be made. But for others, the name assigned was only the closest of several similar species. The new species name assignments are now documented in USPG’s online database in the Germplasm Resources Information Network (GRIN). Assigning these genebank resources a definite species name provides a practical platform for deploying them for research and breeding.