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January 25, 2021
The wild plants that grow along our roadsides and ditches—like the salt-tolerant wild sunflowers and disease-resistant wild pumpkins—may hold crucial traits that can protect our food supply. Breeding commercial food crops using their wild relatives can help those crops become more pest and disease-resistant and resilient in the face of climate change. But according to a new study, many of the “crop wild relatives” are endangered in their natural habitats and in dire need of conservation.
Colin K. Khoury, the study’s lead author, has been a long-time advocate of wild plants and food crop diversity. He has worked for seed companies and seed conservation nonprofits, including Native Seeds/SEARCH. He currently works (remotely) for the International Center for Tropical Agriculture in Colombia and is also a researcher at Saint Louis University, based at the U.S. Department of Agriculture’s Ft. Collins, Colorado facility.
Civil Eats spoke with Khoury about the study, the threats to these plants, and what can be done to help crop wild relatives thrive.
You have written that “the future is going to be a lot wilder and weedier” and that this wildness and weediness will be key to our success. Why are these wild relatives so important to our future?
Agriculture is this ironic field that requires genetic diversity to persist, but also is always reducing this diversity down. That reduction has to do with our modern system, with technology and the fact that you need uniformity in the field to make industrial-scale agriculture happen. It also has to do to do with the small number of seed companies. At the same time, diversity enables agriculture to deal with pests and diseases; if you have the same plants in the field, it’s a lot easier for a pest to “unlock” that variety and eat it all.
In more traditional systems, farmers plant lots of different crops and varieties. Conventional agriculture, on the other hand, gets away with uniformity by every few years changing the varieties that are grown. This means plant breeders go to the seed banks and find new traits. They’re continually mixing and matching. And our crops’ wild ancestors are the major source of this genetic diversity.
On top of that, climate change is forcing agriculture to change faster. Even the coldest average temperatures are now a lot hotter than they used to be. So, plant breeders need to find varieties of wheat or corn that are more tolerant to heat. Those traits can be found in the wild relatives. They’re the plants that thousands of years ago people figured out how to domesticate.
For example, wild sunflowers grow on the roadside in Colorado. They’re the species from which our cultivated sunflowers come. Those are now grown by farmers across the U.S., in Canada, Eastern Europe, the Mediterranean, and South America, but they came from here.
As people domesticated these crops, they [bred] for taste and size, but left other traits behind. So, in the wild, there is all this genetic material that we’re now finding to be useful. Wild sunflowers can adapt to a lot colder and hotter situations than the ones in the fields. And they are close enough cousins that you can cross them and bring in these traits without too much trouble. They don’t require genetic engineering or expensive technology to move traits from one species to another. The idea behind going back to the wild is that genetic diversity is the foundation of how we are going to make it through.
Interestingly, there are places where the interactions between cultivated crops and wild relatives continue naturally. There are parts of Mexico where wild maize grows, and it is encouraged by traditional farmers because they know that a little bit of mixing helps make their crop more resilient. It’s amazing. That knowledge is indirect and goes way back.
Have these wild relatives already been used to improve current commercial crops?
Virtually every crop we eat from the supermarket has already benefitted from breeding with a crop wild relative. So, it’s not an esoteric or marginal practice. You could not have industrial tomato production without a lot of breeding with wild relatives.
The biggest seed companies have their own seed banks, although they also use the USDA’s public seed bank system. In the developing world and in the U.S., university programs also act as seed banks and do genetic breeding using wild crop relatives.
These crops have also actually saved commercial crops a number of times. North American native grapes saved the European grape industry in the 1800s. When a soil-burrowing insect pest called phylloxera was brought to Europe from North America, it wiped out vineyards in France and other countries. Researchers found that the roots of wild grapes in North America were resistant to it, so they encouraged European growers to graft their varietals on top of those roots.
Indigenous communities have used wild plants for millennia to feed themselves and for cultural purposes. They have also for many years called for their conservation. Is the scientific community just catching up?
Some conservationists in agriculture have been warning for decades that we’re losing important diversity to human activity. That’s not really new. But the combined voices are getting stronger because there is more science underneath it. That’s the reason we were able to publish our paper in a high-level scientific venue. Compiling information on hundreds and hundreds of species, in a way where you can compare them all, has taken many decades of people recording who the species are and where they live.
I fully agree that Native people’s traditional knowledge has incredible wisdom and it has not been listened to enough. The way that crop wild relatives have contributed to modern agriculture is mostly through a stream of public and private research, companies, and people with money . . . and Native people have largely been outside of that conversation.
Really inclusive research, that’s not just extracting information from Native peoples, is collaborative and requires a different timeframe and trust building. Those brought up in western science are not used to doing this and that’s why the amount of research that’s truly collaborative and inclusive is a very minor portion of it. But it’s slowly changing and that’s exciting.
What are the biggest threats to crop wild relatives?
The primary threat is the modification of their natural habitats by people, including developing it into farmland and constructing new homes. The second driver for the loss of for wild species in general is climate change.
Most of the information on the impact of climate change on crop wild relatives is still obtained by modeling future climates, rather than already seeing effects. One famous study predicts that species may completely disappear . . . but the more likely scenario is that a species may lose its range size and many of its populations, but others will be able to hold on. In addition to modeling, there is now real evidence coming in from [Israel, part of the] the Fertile Crescent that some populations of wild wheat and barley relatives have already been affected by hotter and drier temperatures.
There are also issues with over-harvesting in some places. Many wild relatives are not that exciting, but others—like wild chili peppers—are very much in demand. People go out and collect them and even prefer them to the commercial varieties because they’re hotter and have different tastes. So, a lot of these populations are disappearing because there are more people in the world and more demand. But you can’t just stop people from collecting culturally important plants. You have to find a balance between the local needs and conservation, and include people in conservation efforts.
We don’t necessarily think of the U.S. as a hub of plant diversity. Yet your study found a richness of wild crop relatives across the country. Was this a surprise?
Yes. My colleagues and I have been doing this work for a while, but despite this we were surprised by how much diversity of agriculturally relevant plants there is. Unlike Mexico, South America, the Fertile Crescent, or South and Southeast Asia, this part of the world is not known as the breadbasket of agricultural historically. So, it was surprising that we have so many cousins of crops that come from other places. The geographic breadth of this diversity was also a surprise. I knew certain parts of the U.S. were rich, like the Southern border, because it’s closer to Mexico where there is more diversity. But we found a diversity of crop wild relatives from the top of Alaska to the U.S. Virgin Islands and Hawaii. It’s everywhere, and that’s amazing and also daunting.
Your study found that half of the plants you surveyed are endangered in their natural habitats, including 7 percent that are critically endangered, and most of the others are vulnerable or nearly threatened. Can you give a few examples of the species we should be most concerned about?
I like to talk about the ones that are listed for protection under the Endangered Species Act. One is called the paradoxical sunflower. It grows only in salty little wetlands in New Mexico and Texas, which are largely on private ranch lands. It’s closely related to the domestic sunflower and it’s super salt-tolerant. We do have some collections of it and the public plant breeders in North Dakota have bred more salt-tolerant sunflowers using paradoxical sunflowers.
Another example comes from Florida, a wild pumpkin called the Okeechobee gourd, and it only grows on the side of Lake Okeechobee, close to Orlando. There’s not much left of it and the species is resistant to diseases that threaten commercial crops in the pumpkin family.
Then there is the Texas wild rice, which occurs only in very clear water on a two-mile stretch of the San Marcos River, the only place in the world, and it’s related to the wild rices that are so important to the Native peoples of the Upper Midwest. There are many other examples.
How should we improve conservation efforts for these plants? Who should be responsible for these efforts?
There are established methods for taking care of these plants. One approach is conserving the plants in seed banks or botanical gardens. It is easier because seed banks are a controlled environment. All you have to know is how to collect the seeds at the right time and how to dry them. Then the seed banks can take care of these seeds for decades and centuries and researchers, educators, and breeders can access the diversity.
The second approach is conserving the plants where they live, in their natural habitats, so they can continue to evolve, so they’re still interacting with pests and diseases, so they continue to serve their functions in the ecosystems, and so they are available to local users. Methods to do that are also well established: Monitor the populations and make changes if populations are declining.
Who should be doing this conservation work is less clear. The USDA is already doing it. But, I want to emphasize that the enormity of the task and the trajectory of how quickly these plants are threatened means it would take us many decades, at the current pace, to get the work done. We need a large effort to verify where the species live today and to do the collecting. And that really requires a lot of field work. Because it’s such a big effort and the USDA has only so much money and people, we’re trying to involve more people—citizen scientists and hobby gardeners.
We have been working for several years now on collaborating more with botanical garden communities all over the country, which have their own conservation systems, professionals, and connections with hobby botanists. They may be willing to go out and check crop wild relatives populations. And I hope we can start a big project where over five to 10 years we can get the work done. It’s not just about the money but also the labor, so we need cool innovative approaches like engaging students over the summers, training them to collect the seeds, and sending them out in teams.
In terms of habitat preservation, we’re working with the biggest landowners in the U.S., federal agencies such as the U.S. Forest Service, the Bureau of Land Management, and the Department of the Interior. We need to contact other big landowners, including Native American tribes, military landowners, state forests, the Nature Conservancy. We’ve made slow, steady progress. It’s not that you need to set aside the land or buy new land, it has to do with creating awareness about these plants. Plants get very little funding, so even on public land such as a National Parks, managers need to be aware that crop wild relatives exist and need protection. They need to create management plans, otherwise they have other priorities like elk and other animals.
Speaking of awareness, what should be the role of raising public awareness and creating more public access to these plants?
There’s a term called plant blindness; it means people don’t know much about plants and they don’t notice them. To counter this trend and create more public awareness, we talk about the role of U.S. botanical gardens, which are especially good at connecting with people. They receive more than 120 million visitors annually. Through exhibits, information, and art, these gardens could feature the wild plants our foods come from.
Your study advocates for the urgent conservation of crop wild relatives. How can we make sure that these plants are not only safeguarded, but that their genetic material continues to be accessible to all who need to use them but may not have the financial means to buy expensive seeds?
More needs to be done on accessibility and availability of crop wild relatives. Nobody should own them . . . this tradition of where crops come from, it goes back thousands of years. Who do you attribute a crop to? It doesn’t make sense to have ownership. Unfortunately, we live in a time when you’re allowed to patent life and it’s not going to end anytime soon. So, a balance needs to be reached. I feel good that the seed bank system in the U.S. is a public resource. It’s available for free, including free shipping, to researchers, plant breeders, and Native American tribes. Due to a lack of funding, it is not available to regular gardeners.
There are also a lot of varied opinions about who should own these plants and who has the rights to benefit from them. There are big politics and a movement towards restricting access in places where the plants originate, and many of these countries feel they have been taken advantage of. It’s unfortunate because the history of agriculture and farmers is about sharing seeds. The problem is that the benefits from breeding those plants have not been shared equitably. I feel strongly that diversity should not be owned, but we also need to recognize the innovation of plant breeding. There needs to be a balance between profits and accessibility. And the public seed bank system needs more support from the government and taxpayers.
Going back to the idea of a weedier, wilder future, do you envision that we may go back not just to using some crop wild relatives to improve current commercial crops, but also to actually growing them in their natural areas and using them in our diets?
Diversification is important for reasons other than its own sake: if you want to obtain the right nutrients for the human body, diversity is a good way of doing it. It’s a major pathway towards better health and nutrition. Our Native foods are amazing; they are also tasty. Have you heard of the pawpaw? Its conservation is happening mainly through a network of people who love them. They are yummy to eat, but the plant is also hard to commercialize because it matures quickly and the fruit is only edible for three days before it goes bad.
There’s a whole suit of plants that would be wonderful if they were added to our diets. There are plants in North America that were on their way to being domesticated into major crops, but when Europeans arrived a whole different trajectory started and they disappeared. One example is the potato bean. It’s native to the South, but when white people arrived, it was being grown by Native Americans from St. Louis to Cape Cod. It was likely part of the first Thanksgiving, then it stopped being cultivated as wheat and other crops came along. But it’s still here. I’ve been growing it for some years!
To bring these plants into our diets, we’ll need the hobby gardeners to spread the passion around. Upscaling is also a challenge. A little bit of plant breeding can make some plants much more productive. That’s what happened with quinoa. It wasn’t known as a food outside the Andes 40 years ago and now it has “exploded,” it’s grown in over 100 countries. Quinoa’s success comes partly from people talking about how great it is, but it is also due to the fact that plant breeders figured out how to grow it in many places. Everyone can play a role in the diversification of the food system.
This interview has been edited for clarity and length.
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