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Undergraduate student, Kristin Reed and Julie Etterson

Seeds Will Tell the Story of Climate Change

Ada Tse polinating early flowering plants with other early flowering plants. She is in the Integrated Biosciences Ph.D program.
Etterson with Michael Benson, a student working on a directed research project.

Julie Etterson’s research team at UMD has shifted the timing of flowering in a native plant species by five days in just a few years of artificial selection. Earlier flowering may be adaptive as climate changes in Minnesota. Now her newest initiative, Project Baseline, will prepare a living seed bank that can be resurrected in the future to study how natural selection has changed wild plant populations over time. Etterson, associate professor, Department of Biology, and principal investigator for the project, was recently awarded a $1.2 million from the National Science Foundation to fund the collection of seeds for a massive seed bank.

The four-year project will fund the collection of millions of seeds from a variety of wild plant species in the U.S. “In 5, 10, or even 50 years, we’ll be able to grow ancestral seeds withdrawn from the seed bank side-by-side with contemporary collections to directly observe evolutionary changes that have occurred. Plants grown from this seed bank could show how a species reacts to drought, insect invasion, or other changes in their surroundings,” Etterson says. “We’ll be able to document adaptive evolution more accurately than we have even been able to before.”

Along with co-principal investigators Steven Franks, Fordham University; Susan Mazer, University of California, Santa Barbara; and Ruth Shaw, University of Minnesota-St. Paul, Etterson will orchestrate dozens of people from research scientists to volunteers, as they collect seed from 34 target species in 20 broadly distributed locations. They’ve divided the working groups into Eastern, Midwest, and Western regions of the country.

At each location, 50 seeds from 200 representatives of each species will be gathered. Another 50 plant species will supplement the collections with an additional 5 million seeds. Seeds will be frozen in liquid nitrogen at a germplasm facility with space donated by the National Center for Genetic Resources Preservation in Fort Collins, Colo.

“It’s important to do this now so future evolutionary biologists can examine how changes, including climate change, have affected these species," Etterson says. Etterson and UMD will manage $816,200 of the funding for the acquisition of seed samples from the Midwest for the next four years.

Chromosome Count

Etterson is also working on another NSF-funded research project utilizing aid from UMD work-study students, students in the UMD Medical School’s Pathways program, directed research students, graduate student researchers, and Undergraduate Research Opportunity Project (UROP) participants.

Etterson is examining whether the amount of genetic material per cell, or the chromosome count, plays a role in adaptation. “Plants have an amazing ability to tolerate genome doubling, a process that results is twice as many chromosomes per cell as would be typical.” Etterson says. “The goldenrod plant species I am working on includes plants with two, four, and six sets of chromosomes. We are examining whether this kind of genome doubling, that is common in plants in general, increases the opportunity for adaptive evolution with climate change.”

Etterson’s experiments at the University of Minnesota Research and Field Studies Center examine differences among plants with different genome sizes for traits such as drought tolerance and flowering time. Her preliminary work suggests that plants with additional genetic material adapt faster. “If goldenrod were to fall behind in the race against climate change,” Etterson said, “it could very well diminish the biological diversity of native plants in our area. A loss of local flora would not only be detrimental from an aesthetic viewpoint, but could also have negative effects on the wildlife that depend upon plant diversity.”

Cross Pollination

In a study which began over five years ago, Etterson and her staff have also been manipulating goldenrod pollination through the process of artificial selection in an effort to produce plants which flower at more extreme times. By breeding early-flowering plants only with other early-flowering plants and late-flowering plants with other late-flowering plants, Etterson and her students have shifted the timing of flowering. Over the course of five years, she has produced populations of plants that flower about three days earlier and a different group that flowers five days later. “As the climate changes and the earth warms, birds arrive earlier and flowers bloom sooner," Etterson says. “By genetically manipulating flowering time (using artificial selection) we are able to determine if plants are blooming earlier as a passive reaction to warmer weather or if they are truly adapting to climate change.” Etterson’s research will improve our understanding of whether changes that we are already observing in the timing of events in wild organisms are just acclimation or adaptive evolution in response to climate change.

Written by Cheryl Reitan with assistance from Zach Lunderberg. October 2011

pollinating floweringtimes seeds
Katie Winkler, a student in the Ph.D. program in Integrated Biosciences, pollinates plants. Two plantings show the goldenrod plants with fewer chromosones (on the left) bloom later. Collecting the seed and the plant material

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