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Title: Accumulation of genetic diversity in the US Potato Genebank

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

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2016
Publication Date: 5/13/2016
Citation: Bamberg, J., del Rio, A. 2016. Accumulation of genetic diversity in the US Potato Genebank. American Journal of Potato Research. 93(5):430-435. doi: 10.1007/s12230-016-9519-3.

Interpretive Summary: Potato (Solanum tuberosum) is the most important vegetable crop in the US and world, and has a rich resource of about 100 wild relative species that can be used for breeding and research to improve the crop. Our national genebank responsible for keeping this resource is the US Potato Genebank, near Sturgeon Bay, Wisconsin. The genebank has been in operation since 1948, and has slowly acquired samples, either as donations from other scientists or from collecting expeditions in natural wild habitats. One basic question is, "Was most of the genetic diversity captured in the first few samples acquired by the genebank in its early years, such that we can stop adding now?" To answer this, we probed almost 400 populations of three model species for the presence of genetic markers and plotted the pattern of new genes added over time. Of course, the rate of capture of new genes has slowed over time, but for all species, significant new genetics continue to be added with new samples. So while the genebank already has captured a lot of the genetics of these species, we would expect even more genes and traits to continue to be added with new samples in the future. To use the mechanic's analogy, we already have a lot of good tools that we need to be familiar with, keep sharp, organized, and put to use, but we should not stop looking for those additional useful tools that could be added to our toolbox.

Technical Abstract: Efficient management of ex-situ collections includes understanding how conservation technologies impact the genetic diversity and integrity of these collections. For over 60 years, research at the US Potato Genebank has produced helpful scientific insights on diverse aspects of potato conservation. The current study investigates how genetic diversity has been accumulated over time at the genebank. The genetic marker (Amplified Fragment Length Polymorphism = AFLP) was used. Samples of a total of 397 genebank populations of S. microdontum (mcd), S. jamesii (jam) and S. fendleri (fen) were analyzed as model species. Populations had been acquired as donations from other genebanks and germplasm researchers, or from collecting expeditions. The results revealed that in all cases gains in diversity took place as more populations were chronologically incorporated in each collection. Assuming the oldest population acquired as the baseline, the number of AFLP markers increased by 56% (mcd), 61% (jam) and 55% (fen). Similarly, additional unique AFLP markers were acquired as more populations were added. Comparisons of germplasm acquired before and after 1992 for jam and fen provided insights into the positive influence of intensive collecting on expanding diversity. The results indicated that germplasm originating from more recent explorations and collecting have indeed provided a significant addition of new diversity into the collections of both species. In summary, this study validated that continuing germplasm acquisitions over time has added significant useful genetic diversity.