Assessing under-estimation of genetic diversity within wild potato (Solanum) species populations

Authors: Bamberg, John; DEL RIO, ALFONSO - University Of Wisconsin

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2020
Publication Date: 10/5/2020
Citation: Bamberg, J.B., Del Rio, A. 2020. Assessing under-estimation of genetic diversity within wild potato (Solanum) species populations. American Journal of Potato Research. 97:547-553. https://doi.org/10.1007/s12230-020-09802-3.
DOI: https://doi.org/10.1007/s12230-020-09802-3

Interpretive Summary: Genebanks aim to maximize the preservation, classification, evaluation and distribution of germplasm in their collections to researchers and breeders who improve the crop for growers and consumers. The US Potato Genebank has many populations of wild potato species' seeds. Some recent reports claim that new DNA markers show that individuals within these populations are quite genetically uniform. In this report we provide evidence that individuals within populations often have quite a lot of variability, and explain the why others' analysis have underestimated it. It is a very important practical difference. If a population is like a toolbox, its usefulness for fixing genetic problems is a lot greater if the tools are of many different kinds rather than if, for example, all the tools in the box are one kind of screwdriver.

Technical Abstract: Genebanks seek to understand the partitioning of genetic diversity among species, populations, and individuals in their collections since this informs decisions for adopting the most effective sampling. Recent reports have suggested that diploid wild species have much less heterogeneity within populations than cultivated forms. We here review past empirical phenotypic trait variation data and examine previous and new DNA marker datasets. We also examine simulation datasets and calculations designed to mimic the effects of artificial biases against wild species heterozygosity due to ascertainment, ploidy, and allele frequencies. Trait data suggests large practical variation exists within populations. Similarly, DNA markers on multiple individuals within diploid wild potato species populations show that substantial heterogeneity in a species is partitioned within populations. Simulations illustrate that biases due to ascertainment, ploidy, and allele frequencies account for much of the apparent homogeneity of wild diploid potato species.