ARS | Publication request: LACK OF ASSOCIATION BETWEEN GENETIC AND GEOGRAPHIC ORIGIN CHARACTERISTICS FOR THE WILD POTATO SOLANUM SUCRENSE HAWKES

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 5, 2002
Publication Date: September 1, 2002
Citation: Del Rio, A.H., Bamberg, J.B. 2002. Lack of association between genetic and geographic origin characteristics for the wild potato solanum sucrense hawkes. American Journal of Potato Research. 79:335-338

Interpretive Summary: Potato genebanks keep genetic resources that are easily and rapidly accessible by breeders and other scientists. To maximize the usefulness of their stocks, genebanks want to capture as many different genes as possible. So genebanks want to have samples of the broadest possible array of natural populations. What factors might predict which populations are most diverse in their genetics? Germplasm collectors have generally assumed that populations separated by long distances or from very different altitudes would tend to be different genetically. This assumption was tested by looking for an association between differences in latitude, longitude, and altitude of natural population of Solanum sucrense, a wild potato species, and differences in their genetic make up. Genetic make up was tested by random DNA markers. Surprisingly, no good associations were detected. Apparently, one cannot very well maximize genetic diversity by collecting populations that are separated by physical distance or altitude. Knowing this makes us aware of the need to find other approaches. Pursuing these other approaches will allow genebanks to maximize the contribution of germplasm to improving the potato crop.

Technical Abstract: Collecting germplasm to broaden breeding resources is an essential activity of genebanks. Research to understand how genetic diversity is partitioned in nature might help to identify collections rich in diversity. Previous studies among wild populations of S. fendleri (disomic polyploid selfer) and S. jamesii (diploid outcrosser) revealed no significant associations between genetic and ecogeographic variation. Even physical separation did not predict genetic differences. In this study, 28 populations of S. sucrense Hawkes (2n=4x=48), a Bolivian species with another breeding system (polysomic polyploid oucrosser) were evaluated. The objective was to assess whether genetic differences between populations are predicted by differences in geographic parameters at the natural site of origin. Genetic differentiation was estimated by using 216 polymorphic Random Amplified Polymorphic DNA (RAPD) markers. The average genetic distance (GD) found between pairs of populations was 31% (ranging from 8% to 44%). Correlations of GD with latitude, longitude, altitude and distance were not significant. Multiple regression analysis also confirmed that GD was not explained by the geographic parameters used. We conclude that geographic origin data is not very useful in gauging interpopulation genetic diversity in the genebank.