ARS | Publication request: Successful prediction of genetic richness at wild potato collection sites in southeastern Arizona

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 2, 2011
Publication Date: October 1, 2011
Citation: Bamberg, J.B., Del Rio, A.H., Penafiel, J. 2011. Successful prediction of genetic richness at wild potato collection sites in southeastern Arizona. American Journal of Potato Research. 88(5):398-402.

Interpretive Summary: Potato is the top US vegetable, so advances in the quality of varieties have a great positive impact on potato farmers and the US consumer. Relatives of the commercial potato growing in remote, mountainous wild habitats hold much value for infusing “new blood” into the crop through potato breeding, but capturing them can be difficult, time consuming and expensive work. Thus there is much to be gained by identifying collection locations with relatively high concentration of unique genes. Our previous work identified one such spot in the Santa Catalina Mountains of Arizona, near Tucson, so this area was prioritized for more thorough collecting in September of 2009. When the new collections were compared with DNA markers to those already collected from nearby sites, predictions that many new genes would be captured were fulfilled. This work demonstrates that DNA markers provide a good objective basis for identifying collecting sites with the best prospects for providing a rich yield of new genes for breeding improved potatoes.

Technical Abstract: Much time, money, and effort is needed to collect even a fraction of the potential geographic range of wild potato species, so there is efficiency to gain if one could predict and prioritize spots particularly rich in unique alleles for collecting. A previous experiment that used AFLP markers to compare “remote” versus “easy” collection sites for Solanum stoloniferum, (previously S. fendleri) within three mountain ranges identified the Santa Catalina Mountains (CAT) of SE Arizona as making a particularly large contribution of unique alleles, despite existing CAT collections being few and all close to roads. This situation motivated a collecting expedition in September 2009 to more thoroughly collect CAT. That expedition resulted in samples of 16 populations, most from new sites never previously described or collected. An analysis was done with 871 AFLP loci, comparing populations from the same three mountain ranges and including the 2009 CAT collections. Results confirmed the prediction of unique allele density of certain location categories within mountain ranges. The new CAT collections captured three times as many unique alleles as contained in the previous collections from that location, and 24 of these were new (unique) among all mountain ranges. One particular new collection, PI 658180, accounted for 46% of the new unique alleles collected in CAT. This study demonstrates the power of DNA markers to empirically identify locations with genetic richness, guiding the most efficient allocation of resources for collecting, preservation, and evaluation of germplasm.