U of G researchers clone a century-old survivor. New research institute advances in vitro technology
Story by Lori Bona Hunt / Photo by Martin Schwalbe
“The wonder is that we can see these trees and not wonder more.” – Ralph Waldo Emerson
There is an American elm tree that has stood, majestic and formidable, on the University of Guelph campus for more than 100 years. The tree has witnessed a century of change and survived against all odds. It towers near Macdonald Hall, its branches and leaves creating a massive, cascading umbrella of green in the sky.
The elm has managed to live, year after year, while nearly all of its kind has died, the victims of Dutch elm disease. The imported fungal infection is so deadly that it has decimated the American elm population that had dominated the North American landscape for centuries.
Before Dutch elm disease took its toll in Canada, American elms were among the most popular and recognizable trees in Ontario, lining boulevards and adorning city centres. Now 95 per cent of them are gone, and most that remain are struggling to stay alive.
Yet the tree near Macdonald Hall has endured. It possesses something the others did not, a natural edge that helps it stand up to the biggest killer of its species.
First discovered in the United States in the 1930s and Canada in the 1950s, Dutch elm disease interferes with water transport and stops nutrients from circulating in the tree. Only about one in 100,000 American elms appear to be able to tolerate the pathogen naturally. U of G is lucky enough to have one tree on the Guelph campus that has survived.
This specimen extends nearly 80 feet into the air. The secret of its success lies within: tangled in its roots, creeping through the branches to the buds of new leaves.
“Any elm tree that has survived initial and subsequent Dutch elm epidemics has tolerance to the disease and is even potentially disease-resistant,” says U of G plant scientist Praveen Saxena. But it is this tree, the gentle giant at the north end of campus that holds a key to developing conservation technologies for reviving the American elm across Canada and beyond.
Tissue samples from its buds are being grown into new plantlets that are genetic clones. If the old adage holds, these “chips off the old block” should indeed be like their parent – natural survivors, able to avoid or tolerate Dutch elm disease.
Cell culture technology could then allow researchers to select germplasm with the desired traits, eventually developing a germplasm that is highly resistant to Dutch elm disease. This process may also broaden our understanding of the basis of plant resistance to pathogens, says Saxena.
Finding ways to produce stronger, heartier elms to reintroduce in Canada has become his quest in recent years. “Despite the knowledge of tissue culture methods for decades, natural American elm trees have been extremely difficult to clone.”
“Look deep into nature, and then you will understand everything better.” - Albert Einstein
Saxena’s pursuit goes beyond bringing back the American elm. Perfecting cloning technologies may also help protect and conserve the Earth’s other endangered plants and trees. And there has never been a more critical time. “Up to 50 per cent of the world’s plant species face the danger of extinction within three decades due to disease, pollution, climate change and other human activities,” he says.
Such rapid loss of plant diversity threatens the health and resilience of all ecosystems and the quality of human life. “The need to conserve endangered plant species is crucial and urgent. We owe it to future generations.”
Philip and Susan Gosling
Saxena has moved closer to his goal with a groundbreaking discovery this spring and the launch of a brand-new research institute at U of G – both achieved with a little help from his friends. Those friends include the members of his plant cell technology lab and his co-investigator, plant agriculture professor Alan Sullivan; Kevin Hall, U of G’s vice-president (research); and Philip and Susan Gosling of the Gosling Foundation, a non-profit organization for ecological preservation and environmental education.
Saxena is known internationally for his work protecting valuable plant species through in vitro multiplication and preservation; he met the Goslings through Sullivan about three years ago. “It was a turning point in my career,” says Saxena. The couple share a fondness for trees and an understanding of the science needed to preserve and conserve them.
In fact, the Goslings have supported other U of G efforts to save the American elm. The late Henry Kock, former interpretive horticulturist at the Arboretum, started the Elm Recovery Project in about 1998. He recruited volunteers to search for surviving elm trees in Ontario to create a seed orchard and cultivate disease-resistant trees. The Goslings supported Kock’s efforts as well as other research and education programs in the Arboretum.
When Saxena met the couple, Susan Gosling, who has a master’s degree in plant genetics, was looking for a research project involving disease resistance; she hoped to help save her husband’s beloved elm trees.
“That really appealed to me,” Saxena says. “I was looking for something that would allow me to apply my scientific expertise and directly benefit people and the environment they live in.”
During their first meeting, Saxena recalls, Philip Gosling kept reminiscing about how elm trees were once abundant in Guelph. Several of the giants had grown in his garden, and a northern oriole used to build a nest in the same tree each year.
That elm is gone now, and so is the oriole.
“Philip is a very intelligent man, and a very direct man,” Saxena says. “He listened to what we had to say and then asked, ‘If the propagation technology is as good as you say it is, then why isn’t anyone using it to save my elm trees?’”
“I speak for the trees, for the trees have no tongues.” - from The Lorax by Dr. Seuss
Saxena remembers explaining the complexity of the research to the Goslings and the challenge in finding private-sector support for expensive work whose only apparent beneficiary is the environment. Most funding candidates want a better return on their investment, says Saxena. “But Philip Gosling said that hearing the musical greeting call of the oriole each spring was a good enough return for him.”
“It was with considerable despair that we saw these wonderful trees die,” says Gosling. “Just think about how a tree sits in the environment: it’s a home for insects, for birds, it produces oxygen, all these wonderful things that we enjoy and take for granted.”
Susan Gosling agrees. “When a tree has Dutch elm disease and needs to be cut down, there is a fair bit of sadness; that’s one of the main reasons why I thought to look at disease resistance. It seems very valuable, not only esthetically in terms of how an elm tree makes the landscape look but also its role in the environment.”
The Gosling Foundation pledged $500,000 initially to support the Guelph researchers’ efforts to develop new cloning techniques for American elm trees. But Saxena knew it would take more, both dollar- and research-wise, to accomplish what he wanted to do.
His break came two years later during a research trip to Jamaica when he met Kevin Hall. Hall had been newly appointed as U of G’s vice-president of research, but this was their first meeting. Saxena explained his dream of taking his elm tree research to the next level, applying the techniques to other species and involving researchers around the world.
Hall recalls: “I told him that this was bigger than what he could do in his lab. It called for a full-fledged institute where we could build a team beyond Guelph. This is advanced science that can make a difference socially, culturally and scientifically. It has the potential to start a whole new vein of research at our university that would help better the planet and distinguish us from all other universities that do plant research.”
Back at U of G, there followed numerous meetings involving the Goslings, Hall and Saxena. This March, the University announced the creation of the Gosling Research Institute for Plant Preservation (GRIPP). Directed by Saxena, GRIPP is supported by a $1.5-million donation from the Goslings through The BetterPlanet Project, the University’s $200-million fundraising campaign.
The institute’s scientists will work to help threatened plants around the world. They plan to develop new interdisciplinary and international collaborations, and run education, outreach and service projects to teach people about the value of conservation, locally and globally.
Profs. Praveen Saxena, left, and
Alan Sullivan with cloned plantlets
“Praveen wants to use world-class science to improve basic human aspects of society and to help the environment,” Hall says. “Creating the institute provides a framework to do this. It opens the door for us to bring new research partners to the table and to attract additional private- and public-sector partners.”
At the institute’s official opening, Philip Gosling said it’s time to get a “GRIPP” on the loss of biodiversity. “We can despair about this, we can regard it as inevitable, or we can say: ‘Let’s do something, let’s save what we can while we can.’ And I think we can do it. We can do research, we can start developing and cloning disease-resistant trees, we can understand how trees and plants develop resistance.”
“The creation of a thousand forests is in one acorn.” - Ralph Waldo Emerson
A couple of weeks after the GRIPP launch, Saxena, Sullivan and their research team made history, announcing they had successfully cloned American elm trees that had survived repeated epidemics of Dutch elm disease. The breakthrough was published March 29 in the Canadian Journal of Forest Research, which is produced by the National Research Council of Canada.
Starting with shoot tips and dormant buds from that Macdonald Hall elm on campus, the scientists produced genetic clones of the parent tree. It’s the first known use of in vitro culture technology to clone buds taken directly from a mature American elm.
Their feat also highlighted what GRIPP can do to preserve and conserve plant species, Saxena says. In vitro conservation technology is efficient and better than seed banks for conserving many plant species. Hundreds of genotypes with known visible features can be conserved in a safe small space and can be easily propagated.
Saxena, Sullivan and Susan Gosling worked on the project with Guelph post-doctoral researchers Mukund Shukla and Maxwell Jones, and with Chunzhao Liu of the Chinese Academy of Sciences in Beijing.
The researchers also announced that they had perfected a way to conserve germplasm over the long term. A germplasm repository now contains 17 accessions collected from surviving mature elms across Ontario, including the specimen on campus.
The research team will now focus on identifying and developing a germplasm that is highly resistant to Dutch elm disease. “While great progress has been made and continues to be made by U.S. breeders working to develop cultivars tolerant of Dutch elm disease, much more remains to be done,” Saxena says. “To our knowledge, no truly disease-resistant germplasm currently exists, perhaps due to our lack of knowledge of complex plant-pathogen interactions.”
Developing a resistant germplasm would allow scientists to grow thousands of genetically identical plants with the same disease resistance, aiding in elm breeding and biotechnology programs around the world, and ultimately allowing American elms to be reintroduced in Ontario and across North America.
Cloning the American elm tree will also serve as a model for propagating and preserving other plants at risk of extinction, Saxena says. He fears ash and maple trees may be next; numerous diseases and human activity are taking their toll. “Canada just isn’t Canada without the maple tree.”
And so it started -- but will not end -- with the majestic elm that has made U of G its home for more than a century. This giant survivor has provided, figuratively and literally, the buds of something that will grow much larger.
That’s the beauty of it, Susan Gosling says. “If we are able to do this with the elm, there are so many more species that need help. This can provide the motivation, the inspiration to carry on. We can be optimistic about the future.”