An Optimized Core Sample of the Wild Potato Solanum Fendleri in the USA

Authors: Bamberg, John; DEL RIO, ALFONSO - University Of Wisconsin; FERNANDEZ, CHARLES - Us Potato Genebank

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2025
Publication Date: 9/3/2025
Citation: Bamberg, J.B., Del Rio, A., Fernandez, C.J. 2025. An Optimized Core Sample of the Wild Potato Solanum Fendleri in the USA. American Journal of Potato Research. https://doi.org/10.1007/s12230-025-10008-8.
DOI: https://doi.org/10.1007/s12230-025-10008-8

Interpretive Summary: The US Potato Genebank has nearly 6,000 samples of wild and cultivated potato samples for use by researchers and breeders to improve the crop. The genebank provides a rapid practical source, but all the genetic potential originally comes from the wild, so it is important to study how best to mine the value in the wild. Genebank staff have collected potato samples in the southwest USA for over 30 years. One wild potato species there has particular breeding value, with over 250 known populations. We recently discovered a single population that has nearly all the genetic diversity know for the species in a single location. In the research reported here, we show that taking many samples (over 150) at this single site, and analyzing them with DNA markers, just seven individuals can be identified that capture 93% of the total genetic value. We have combined these seven samples into a single bulk seed lot. This research serves as a model for how genebank curators can seek and create one ultimate seed sample to offer their clients that gives the most efficient representation of a potato species. That should save time and money in germplasm evaluation, thus speeding the incorporation of good traits into the crop for reducing pesticide use, improving eating quality, and promoting profitability.

Technical Abstract: Solanum fendleri (fen) is one of two wild potato species native to the USA. The US Potato Genebank has 269 samples, over 90% of which were collected by the authors in annual expeditions to the states of Arizona, New Mexico, and Texas since 1992. For the ultimate in efficiency for germplasm representation of a species in the genebank one would: 1) acquire many population samples from the broadest possible eco-geographic representation of the range, 2) identify the minimum number of populations that collectively capture the maximum amount of diversity (a core subset), 3) identify the minimum number of individuals which, when combined as parents, collectively capture the maximum genetic diversity in a single new population. In 2016 we published a recommended core subset of fen from the USA. In 2020 we reported the discovery of a single very large “mega-population” of fen near Tucson, AZ that by itself could be considered a core subset of the species, capturing most of the known USA fen genetic diversity. We further optimized sampling of that mega-population site by collecting 160 dispersed individuals, genotyping them at 32K GBS loci, selecting 38 plants that capture 93% of the allele diversity and 71% of unique alleles, and then intermating those 38 plants. This study is presented as a model for composing the ultimate genebank sample of a species-- the richest and most efficient representation of fen diversity in the USA packed into a single seedlot for sharing with researchers, breeders, and other genebanks.