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Just Cloning Around: Getting to the Root of Genetic Diversity

In August, CREW staff traveled down to Daniel Boone National Forest in Kentucky to accompany the US Forest Service in their annual survey of our Cumberland sandwort experimental outplanting. The Cumberland sandwort is a small, delicate plant that clings precariously to the sandy soil of sandstone rock formations in the Cumberland Plateau of southern Kentucky and northern Tennessee. It is endangered, in large part due to trampling by hikers and people scavenging for Native American artifacts. CREW has been working with the US Fish & Wildlife Service to help preserve and protect this little plant.

Cumberland sandwort (Arenaria cumberlandensis) in bloom.

Cumberland sandwort (Arenaria cumberlandensis) in bloom.

Using seeds collected in 1994 from Pickett State Park in Tennessee, CREW established 10 genetic lines of the Cumberland sandwort in our tissue culture lab, and we banked each line in liquid nitrogen in our CryoBioBank. In 2005, to test whether the plants grown by tissue culture could be used to re-establish a population if needed, CREW and the US Forest Service planted 77 plants from our tissue culture lab in a sandstone cave in Daniel Boone National Forest that had a habitat similar to the native habitat of the sandwort. On our August 2013 trip to that experimental outplanting, we counted 160 plants!

collecting

CREW staff collecting leaf samples. Left: Omer Donmez Right: Megan Philpott

It looks like our experimental outplanting is flourishing in its new location, so now we want to look at the genetic diversity of the outplanting. Genetic diversity in a population is important because it allows the population to adapt to changing environments, or to survive and develop resistance to disease. Although we had started with 77 plants, they were all clones of the 10 original genetic lines established in our tissue culture lab. On our trip, we collected leaf samples from 35 individuals to analyze using microsatellite markers. For comparison, we also traveled down to the two locations in Pickett State Park that our original seeds were collected from and collected about 150 total leaf samples from the two large populations. Now we’re working on extracting DNA from the nearly 200 leaf samples collected this August. We should be able to compare the amount of genetic diversity generated in the experimental outplanting with the amount of genetic diversity naturally found in the original populations. This study is part of a larger study where we are evaluating the genetic stability of tissues that have been stored in liquid nitrogen for up to 20 years – a project that is supported in part by a grant from the Institute of Museum and Library Services, as well as CREW’s Eisenberg Fellowship. It should give us insight into how to manage and protect threatened and endangered plant populations more effectively. Keep an eye out for our results!

Sandstone rock habitat of Cumberland sandwort

Sandstone rock habitat of Cumberland sandwort

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