In 1978, Kim Steiner, professor of forest biology at Penn State, worked with colleagues to plant 2,000 ash trees on the University Park campus. Today, student Chelsea Kyler is conducting research in that plantation, which was established years before she was born.
The senior forest science major (forest biology option) from Sheffield is focusing on the effects of the emerald ash borer, an invasive beetle native to Asia. She is studying green ash as part of the multi-university Hardwood Genomics Research Project developed by John Carlson, director of the Schatz Center for Tree Molecular Genetics, which is housed in Penn State's College of Agricultural Sciences.
Emerald ash borer infestations spread quickly and easily because the beetle has not been in North America long enough to establish a significant number of natural predators, Kyler explained. The beetle, which first was detected in the United States in 2002, bores into the trunks of ash trees and feeds on nutrient-conduction tissue, eventually killing its host.
Kyler stressed the significance of the destruction caused by the beetle. "Ash trees are an important food source for wildlife," she said. "It's important to know that there are many chains of dependency in nature, and even though we don't always see them or know they are there, they really are.
"The loss of an entire species can have a number of negative effects on the ecosystem."
Kyler noted that some scientists are comparing the emerald ash borer infestation to the chestnut blight, a devastating fungal disease that virtually wiped out the American chestnut tree in the early 1900s.
Although wood from ash trees is used most prominently in manufacturing baseball bats, these trees also have noncommercial importance. "Ash trees are prized for their ornamental value," Kyler said. "Some Native American tribes use ash wood in basketry as a way to express their cultural heritage."
Kyler hopes to determine how genetics influence the susceptibility of green ash trees to the damage inflicted by the emerald ash borer.
"We want to know if there are genes responsible for attracting or defending against the beetle," she said. "If there are, we can use that knowledge to selectively breed ash trees with the more defensive characteristics."
To battle this pest, Kyler is taking DNA samples from every ash tree in the plantation. She will then compare the genes in the ash trees that appear to have some degree of resistance to the beetle to the DNA of ash trees that seem to fall victim to the beetle faster.
The plantation was established originally to study variation in growth traits among different populations of green ash (Fraxinus pennsylvanica) from across the eastern United States and Canada.
"That was long before anyone knew that ash species would be threatened by the exotic emerald ash borer," Carlson said. "Such tree genetics plantations continue to be as important a resource in the current era of genomics as they were to previous generations of students who conducted research at Penn State."
In the present stage of her project, Kyler is collecting tissue as well as extracting DNA. "Considering the large number of trees in the plantation, I have a lot of work to do in a short amount of time," she said. "Each DNA extraction is carried out as a two-day process."
But she will have adequate funding for her work. Kyler applied for and obtained undergraduate research grants for summer and fall semesters from the College of Agricultural Sciences.
"That's a big accomplishment for an undergrad," Carlson said.