Biotechnology offers a holistic approach to restoring endangered forest tree species

WEST LAFAYETTE, Ind. — Many endangered forest tree species are likely to need biotechnology alongside traditional tree husbandry approaches to survive, according to insights published in the July issue of the journal New forests.

Douglass Jacobs of Purdue University and Kasten Dumroese of the US Forest Service led a team of 19 co-authors, including scientists, land managers and regulators, in presenting their findings on biotech risk assessment and forest tree restoration. They New forests the paper, published in a special issue on threatened tree species, presents key findings from a 2021 virtual international conference on the issues.

Among their conclusions: Society drives policy. If genetic engineering is the only way to save some species, its use will require public acceptance.

“Biotechnology is a diverse toolkit that includes different technologies that can be used to impart resistance to pests — it could be insects or pathogens — in our threatened forest trees,” said Jacobs, Fred M. van Eck Professor of Forest Biology. . But many people mistakenly equate biotechnology with genetic engineering.

“Traditional tree breeding, whether breeding different species or different varieties within a species, has been going on for thousands of years. And the regulations on planting trees that have been traditionally bred are open,” he said. “Genetic engineering, on the other hand, is highly regulated, but all biotechnology is certainly not genetic engineering.”

Scientists often use genomics, for example, which involves working with the full set of genetic material in an organism to learn more about what causes disease. Genomics can also help identify genes responsible for useful traits such as resistance to parasites.

Downy mildew began afflicting the American chestnut in the 1900s, killing billions of trees. Despite being the target of decades of tree-raising efforts, the chestnut’s prospects remain uncertain. The endangered species list also includes ash, butternut, and bristlecone pine among other members of the five-needle white pine family.

“I feel a sense of urgency. We can’t take a hundred years like we did the chestnut to move on,” said Dumroese, a research plant physiologist at the Forest Service’s Rocky Mountain Research Station in Idaho.

“Species are going ecologically extinct,” Dumroese said. “They are unable to provide their historical level of ecosystem function because they often do not reach maturity. And this is happening at an ever faster pace. See how rapidly we have lost ash trees from our forests and urban landscapes due to the introduction of the emerald ash borer, a pest insect.”

Western white pine is an example of how the Forest Service, since the 1960s, has actually used traditional tree management to deal with white pine blister rust. However, the white pine population remains below pre-blight blister levels and may never be fully restored.

“But we see a lot more western white pine in the landscape and it’s being planted in the landscape every year because of these efforts,” Dumroese said. “That process only took a couple of decades where we went from a big problem to making improvements. We need that pace for all the species we call endangered.”

Back in Indiana, the Hardwood Tree Improvement & Regeneration Center, a joint effort between Purdue and the Forest Service, has maintained a pest resistance breeding program for years. Nearly all of the center’s efforts to date have focused on traditional tree breeding and genomics.

“The opportunity to work with chestnut and help reintroduce it into the landscape was a major reason I took the job at Purdue in December of 2001,” Jacobs said. “Watching species disappear from the landscape gives me personally a lot of motivation to contribute everything I can to help save some of these endangered species.”

Over the past 10 years, Jacobs has seen remarkable advances in new biotechnologies using genomics and genetic engineering.

“For some species, traditional tree breeding does not appear to be a viable long-term option for disease-resistant trees. In those cases, it will probably be genetic engineering if we are to save the species,” she said.

This is also true for a species such as the downy mildew-afflicted American chestnut, which has been the subject of a 50-year breeding program. “It’s probably not possible to introduce enough chestnut and ash trees to get us back to the pre-disorder level in anyone’s life, but you have to start somewhere,” Dumroese noted.

Participants at the 2021 conference came to a consensus on the applicability of biotechnology to the reintroduction of some threatened forest tree species. They came from academia, the Forest Service, and organizations like the American Chestnut Foundation and the Nature Conservancy.

“Society perception and politics remain the weakest links,” Jacobs said. “There was this constant one-way flow of information from scientists to the public with the idea of ​​’Hey, we’re scientists, trust us.’ Or “We are the government, trust us.” But you need a much more interactive dialogue to be able to change public opinion.”

Support for the conference and related work was provided by the US Department of Agriculture Forest Service and the National Institute of Food and Agriculture.

Writer: Steve Koppes