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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION AND UTILIZATION OF POTATO GENETIC RESOURCES Title: Intuitive visual impressions for identifying clusters of diversity within potato species

Authors
item Bamberg, John
item Del Rio, Alfonso -

Submitted to: American Journal of Potato Research
Publication Type: Proceedings
Publication Acceptance Date: March 27, 2013
Publication Date: February 1, 2014
Citation: Bamberg, J.B., Del Rio, A.H. 2014. Intuitive visual impressions for identifying clusters of diversity within potato species. American Journal of Potato Research. 91(1):32-74.

Technical Abstract: One of the basic research activities of genebanks is to partition stocks into groups that facilitate the efficient preservation and evaluation of the full range of useful phenotype diversity. While much time and effort has gone into carefully measuring defined physical taxonomic characters and DNA markers, the resulting species limits in potato have been shown to have low predictivity for most useful traits. We sought to test intraspecific grouping done with the ultimate of simplicity: rapid, replicated, visual impressions by multiple un-coached observers, or "unsupervised classification" in the terminology of categorization science. All of the 14 populations of the wild species Solanum okadae in the genebank were thus examined in two separate grow-outs for a total of 21 times by 7 genebank staff members. We coined the term "cog" to represent a group of populations "known" as associates for unspecified reasons by a simple unbiased visual impression. Consistency of cogs varied among and within individuals, but the composite provided an unmistakable consensus of two cogs, one containing 4 populations, and the other containing the remaining 10 populations. Upon examination of these cogs, it was found that they perfectly match the natural country of origin (Bolvia versus Argentina). The four-member cog was early referred to as "big-leaf" or "big oka". Indeed, AFLP markers resolved two genetic groups of populations that exactly matched the two cogs and associated the big-leaf cog with sympatric populations of S. microdontum, a related species with larger vines and leaves. After cogs are examined and their practical basis validated, we propose they would be given descriptive names or take the rank of "form" in the genebank inventory.

Last Modified: 10/24/2014
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