The solution depends on regulators, scientists and public support
Douglass Jacobs, the Fred M. van Eck professor of forest biology at Purdue University, with a butternut tree that was infected with canker. Butternut is on the list of endangered forest tree species likely to need biotechnology alongside traditional tree farming approaches to avoid extinction. (Photo by Purdue Agricultural Communications/Tom Campbell)
WEST LAFAYETTE, Ind. — Many endangered forest tree species will likely need biotechnology alongside traditional tree husbandry approaches to survive, according to insights published in the July issue of the journal New Forests.
Douglass Jacobs and Kasten Dumroese of the US Forest Service’s Purdue University 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. Their New Forests 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, could it 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 you’re breeding different species or different varieties within a species, has been going on for thousands of years. And regulations on planting trees that have been traditionally raised are open, he said. Genetic engineering, on the other hand, is highly regulated, but all biotechnology is hardly 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 breeding efforts, the chestnuts’ prospects remain in doubt. 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. It can’t take a hundred years like we did the chestnut to move on, said Dumroese, a research plant physiologist at the Forest Services’ Rocky Mountain Research Station in Idaho.
Species are ecologically dying out, 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.
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 endangered species that were calling.
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 chance 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 do whatever I can to 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 obtaining disease-resistant trees. In those cases, it will probably have to be genetic engineering if we are to save the species, he 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. Introducing enough chestnut and ash trees to bring us back to the pre-disorder level probably isn’t possible 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’s perception and politics remain the weakest links, Jacobs said. There’s been this consistent one-way flow of information from scientists to the public with the idea of, Hey, we were scientists, trust us. Or I was the government, trust us. But you need a much more interactive dialogue to be successful in changing public opinion.
Support for the conference and related work was provided by the United States. Department of Agriculture Forest Service and National Institute of Food and Agriculture.
—Steve Koppes
Purdue University
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