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Title: Pesticide contamination has little effect on the genetic diversity of potato species

Author
item DEL RIO, A - University Of Wisconsin
item Bamberg, John

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2012
Publication Date: 10/1/2012
Citation: Del Rio, A.H., Bamberg, J.B. 2012. Pesticide contamination has little effect on the genetic diversity of potato species. American Journal of Potato Research. 89(5):384-391.

Interpretive Summary: Wild potato populations in nature are the backups for the samples kept in genebanks for research and breeding that lead to an improved potato crop. Some of these wild potato species are known to grow naturally in close proximity to cultivated fields in Latin America, thus are potentially impacted by human activity, including exposure to pesticides. Our previous work found that wild potatoes known to grow in or near pesticide-treated fields in central Peru had significantly less flowering and pollen production when samples were intentionally exposed to the pesticide in greenhouse conditions. It is possible that such reduced fertility could result in the accidental loss of genes over generations. We compared the DNA fingerprints of offspring of pesticide-exposed plants to those of plants not exposed to pesticide and found that they were quite similar. It appears that populations close to farmers’ fields exposed to pesticide may produce less seeds, but those seeds, if collected for the genebank, would be expected to have similar genetic richness as populations collected in more remote areas.

Technical Abstract: Our previous study examining the effects of agrichemicals on the reproductive capacity of potato species revealed that the pesticide carbofuran negatively influenced flowering duration and pollen viability. These changes could limit reproductive ability non-randomly, modify allelic frequencies, and cause genetic drift. This study utilized Simple Sequence Repeat (SSR) markers to examine that possibility by assessing the genetic structure of progenies derived from potato populations exposed to two levels of carbofuran. A total of eight populations of five potato species (acl, buk, hcr, med and rap) were evaluated. An untreated, uncontaminated population was included as control for comparison. The results revealed that most of the 116 SSR allele frequencies assessed did not differ significantly between control and progenies of pesticide-contaminated parents. A few markers showed a significant frequency shift in some species, specifically buk and med. However, this study reveals that although the pesticide reduces reproduction in wild potato species populations, changes in population genetics are minor and do not significantly threaten diversity.