|Del Rio, Alfonso|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2001
Publication Date: N/A
Citation: Interpretive Summary: Potato genebanks want to collect and store samples that are as genetically diverse as possible. Since wild populations grow in many different locations and habitats, an obvious question is: Do eco-geographical aspects of the sites of origin for wild potato populations predict the genetic differences among those populations? For example, are genetic patterns correlated with differences in altitude, rainfall, average temperatures, latitude, etc.? When genetic differences among 96 populations of wild potato species from the southwest USA were assessed with DNA markers (RAPDs), a surprising lack of any such correlations were found. Even the physical distance of separation was not a very good predictor of genetic differences between populations. This work shows germplasm collectors that "common sense" assumptions about how to sample from the wild may not be very reliable. So, perhaps the best way to be sure to maximize the capture of genetic diversity from a region is to collect as many samples as possible. Then the most diverse populations can be be selected for deposition in the genebank later based on DNA tests. Genetic improvement is one of the pillars on which the promise of better potato varieties rests. This research shows genebanks how to more efficiently and effectively gather samples of potato genetic diversity. This will make it easier for breeders to produce varieties that are more productive, nutritious, and affordable yet profits the farmer while reducing the use of chemicals that threaten the environment and human health.
Technical Abstract: Collecting germplasm would be more efficient if we could identify factors in the wild that predict areas and habitats associated with greater genetic differences and diversity. The objective of this research was to investigate whether eco-geographical variables have significant associations with patterns of genetic diversity. This study examined 96 wild potato populations collected from the southwestern United States: 43 populations of Solanum fendleri (2n=4x=48) and 53 populations of S.jamesii (2n=2x=24). RAPD markers were used to assess populations in two ways: determination of simple genetic difference between pairs of populations, and genetic diversity of a population, based on the frequency of its RAPD markers in the whole set. Results from 2,282 comparisons indicate that patterns of genetic differences are not associated with any differences in eco-geographical structure assessed. Even geographical separation of populations, a parameter usually considered important when collecting germplasm, did not predict genetic difference very well. Latitude, longitude and heat-related factors significantly predicted genetic diversity in S. fendleri but not in S. jamesii. This experiment revealed few associations between eco-geographic parameters and genetic variation in the wild. Thus, collecting across the range of geography and habitats may not result in the similarly representative genetic sample one might expect. The recommendation, therefore, is to collect from as many populations as possible and, if necessary, select and incorporate a manageable subset into the genebank based on empirical measurements of genetic diversity.