TED Talks Daily - The food that fertilizes itself | Giles E.D. Oldroyd

Episode Date: February 20, 2025

Could the key to a sustainable food system already be growing in the world’s farms? Plant scientist Giles E.D. Oldroyd explores how a special quirk of soybean plants allows them to naturally partner with networks of fungi and bacteria to access essential nutrients in the air and soil — eliminating the need for synthetic fertilizers. He shows how harnessing these microscopic powerhouses could help scientists rewire crops to make their own fertilizer, reducing pollution, increasing yields and improving livelihoods for smallholder farmers. Hosted on Acast. See acast.com/privacy for more information.

Support for this show comes from Airbnb. Last summer my family and I had an amazing Airbnb stay while adventuring in Playa del Carmen. It was so much fun to bounce around in ATVs, explore cool caves, and snorkel in subterranean rivers. Vacations like these are never long enough, but perhaps I could take advantage of my empty home by hosting it on Airbnb while I'm away. And then I could use the extra income to stay a few more days on my next Mexico trip. It seems like a smart thing to do since my house sits empty while I'm away. We could zipline into even more cenotes on our next visit to Mexico.

Your home might be worth more than you think. Find out how much at airbnb.ca slash host. This episode is sponsored by Audible Canada. I'm excited to tell you about a new podcast that offers a fresh perspective on how we define success. It's called The Unusual Suspects with Kenya Barris and Malcolm Gladwell. As a podcast host, I'm always curious about what makes exceptional people tick. The Audible Original Podcast offers an insightful exploration into the minds of notable figures from various fields like entertainment, sports, and business.

The show's hosts Kenya and Malcolm combine their unique perspectives in a casual living room style conversation with guests like Jimmy Kimmel, Ursula Burns, and Ava DuVernay. No scripts, no agendas, just raw honest chats about their journeys. In this 8 episode series, you'll hear unfiltered stories of perseverance, resilience, and the sometimes unconventional choices that have led to the guests' achievements. Go to audible.ca slash unusual suspects podcast and listen now. This episode is sponsored by Cozy. Remember the last time you moved a couch? Nightmare, right? Well, Cozy is changing the game. They're a Canadian company making modular, high-quality furniture that arrives in compact boxes that are easy to carry. And Cozy's pieces grow

with you. Start with a love seat, then easily expand to a sectional as your family grows. And comfort? Their Cielo collection is like sitting on a cloud, perfect for unwinding after a long day of hosting podcasts. What really stands out is the adaptability. These pieces are built to last, designed to be disassembled and reassembled without losing stability. It's furniture that evolves with your lifestyle. Customize your perfect piece today. Your back and your style will thank you. Transform your living space today with Cozy. Visit Cozy.ca spelled C-O-Z-E-Y to start customizing your furniture. Cozy. Modern living made simple for you. Modern Living made simple for you.

You're listening to Ted Talks Daily, where we bring you new ideas to spark your curiosity every day. I'm your host, Elise Hugh. We're about to get a little geeky about soybean plants. That's right. In his 2024 talk, plant doctor Giles Oldroyd lays out the rather magical way soybean plants work and the important role they can play in sustainable agriculture. Enjoy.

So I believe this soybean plant is a prototype for sustainable food production on this planet. So on the roots of this soybean plant are nodules, and these nodules do an amazing thing. They harbor millions of bacteria inside the cells of the nodules, and those bacteria are able to capture nitrogen out of the atmosphere and confeed it to this soybean plant. Now, all plants require a source of nitrogen. They need it so they can make DNA, RNA and proteins.

But plants can't access the most prevalent form of nitrogen on the planet, the 78 percent of the air that you're currently breathing, that is molecular dinitrogen. Only bacteria that possess the enzyme nitrogenase can convert this very inert form of nitrogen and convert it into ammonia, a reactive form of nitrogen that bacteria and plants can use to make their DNA, RNA and proteins. So the bacteria inside the nodules of this soybean plant are fixing nitrogen out of the air, converting it into ammonia

and then feeding that ammonia to this soybean plant. In return, the soybean plant is feeding the bacteria with a source of carbon in the form of sugars, derived from photosynthesis in the leaves. This is what we call a mutualistic symbiosis. It's beneficial to the soybean plant, but it's also beneficial to the bacteria inside those nodules. Now, the roots of the soybean plant are doing a second amazing thing,

and to see that, we have to look under a microscope. The roots are heavily infested with a beneficial fungus called mycorrhizal fungi, and these fungi are heavily colonizing the soil and make much greater contact with the soil surface than the plant root alone is able to achieve. In so doing, they create a much more efficient platform for the uptake of nutrients,

nutrients such as phosphates, nitrates, potassium and water. The fungus isn't only out there in the soil, it's also colonizing the roots of this soybean plant, where it makes these highly branched fungal intrusions into the cells of the root that we call our arbuscules. So the fungus is out there in the soil, capturing nutrients from the soil, and it feeds those nutrients to this soybean plant

through these arbuscular intrusions. In return, the soybean is feeding the fungus with carbon from photosynthesis. Again, it's a mutualistic symbiosis. So this soybean plant can get almost all of its phosphate and the totality of its nitrogen needs met through these beneficial microbial associations. And that provides a free and sustainable means

to support its crop production. And out in nature, most plants are engaging with one or more of these beneficial microorganisms to help them capture these limiting nutrients from the environment. But in agriculture, it's a really different situation. There, we're applying these nutrients at high concentrations in the form of inorganic fertilizers to support our crop production. And while inorganic fertilizers have underpinned global food security

for the last 60 years, they cause significant environmental pollution, they cause significant greenhouse gas emissions, they contribute to a lot of the costs in our crop production, and at the other end of the spectrum, smallholder farmers lack access to those fertilizers and their productivity suffer as a result. For all of these reasons,

myself and my colleagues in the ENSA project are working to eradicate, or at least greatly reduce, our reliance on inorganic fertilizers. To do that, we want to make all of our crop plants, particularly our cereal crops, behave like this soybean plant, able to get their nutrients through these beneficial microbial associations.

Now, the fungal symbiosis is not limited to legumes like that soybean. It's actually pretty widespread within the plant kingdom, and it's already present in our cereal crops. However, when we fertilize our fields, the crop doesn't engage with the fungus. Why pager the fungus with carbon if the nutrients are not limiting? So while soils in natural ecosystems are packed full of a complex network of these mycorrhizal fungi fed by their host plants,

our agricultural soils are greatly depleted for these beneficial fungi. If we want to really maximize the utilization of this fungal symbiosis in agriculture, then we need to get our crop plants to gauge with the fungus much more proactively, and even when we fertilize our fields. If we can do that, then we can reduce the levels of fertilizers we use,

and we'll lose less of those nutrients out into the environment. So to achieve that, we set about identifying the genetic regulators that control when the plant engages with these beneficial fungi. And we discovered that these protonaceous regulators are only present when the plant is starved for nutrients. And we were able to rewire that system so that now the plant engages with the fungus much more proactively

and even when the plant engages with the fungus much more proactively, and even when the plant is fertilized. In our field trials, we find that these rewired barley plants get 10 times as much fungus inside their roots. That's a lot more fungus in the crop, but it's also a lot more fungus out there in the field. So now we can control when the plant engages with these beneficial fungi. The next step for us is to test, does that mean we can lower the fertilizer levels and still maintain good production? I believe this is a first step

to really getting that fungal association working for us much more proactively in agriculture, and that's going to be really important, especially for how much phosphates we have to apply to our fields. But if we're going to really cure our addiction to inorganic fertilizers, we also need the nitrogen-fixing bacterial symbiosis. Now, unfortunately, the nitrogen-fixing symbiosis is limited to legumes, like that soybean and their relatives.

So we are working on transferring that nitrogen-fixing symbiosis from legumes to our cereal crops. Myself and my colleagues have spent the last 30 years undertaking genetic dissection to try to identify all the genes that, in soybean, allows it to engage with those nitrogen-fixing bacteria. During that time, we've identified many genes that are involved in that process.

But surprisingly, we haven't yet identified a single gene that is novel to that soybean plant. In fact, the genes are already present. Most of them are already present in our cereal crops. Let me give you an example, the symbiosis signaling pathway. This is a set of proteins that are expressed on the cells

on the surface of that soybean root that allow the soybean plant to recognize the nitrogen-fixing bacteria out in the soil. When they recognize the bacteria, they oscillate their calcium in the nucleus. This is essentially the cell saying, I've seen these beneficial bacteria out in the soil, now turn on the gene expression that's necessary

to let those bacteria in. This symbiosis signaling pathway, that in the soybean plant, allows it to perceive the nitrogen-fixing bacteria, is already present in our cereal crops. And that's because it's the same signal transduction pathway that allows all plants to recognize mycorrhizal fungi. What we now understand

is that when legumes evolved this capability to engage with nitrogen-fixing bacteria, they didn't invent anything new. They used the preexisting genetic components associated with the engagement with beneficial fungi to also allow engagement with beneficial bacteria. Essentially, the nitrogen-fixing symbiosis is really just a modified form of the mycorrhizal fungal symbiosis

with a few tweaks. And one of the mycorrhizal fungal symbiosis with a few tweaks. And one of the really important tweaks is to link that symbiosis signaling pathway to root organogenesis to make the nodules that are able to accommodate those nitrogen-fixing bacteria. But even there, these apparently unique nodule structures are not that novel. They use preexisting developmental genes that are already present in our cereal crops.

So essentially, nitrogen fixation uses a whole set of preexisting genetic components, but they re-network them in a novel way to create the apparent novelty of nitrogen fixation. Now, from an engineering perspective, it's much easier to re-network a set of pre-existing genetic components than it is to build those genetic components from scratch. Now, this work is not yet published, but using this knowledge and getting the networking of those preexisting genetic components right,

we have now been able to engineer nodules in non-legumes. Now, unfortunately, at the moment, those nodules don't get infected with the nitrogen-fixing bacteria. That's the step that we're currently working on. However, I believe we are well on track to delivering nitrogen-fixing cereals. And because we're re-networking preexisting genetic components, as opposed to having to build those genetic components from scratch, I'm pretty confident that we can deliver those nitrogen-fixing cereals

within my career. Nature has already shown us how to sustainably feed this planet. I believe the next green revolution is going to be the microbial revolution, using beneficial fungi to deliver phosphates and beneficial bacteria to deliver nitrogen, providing a much more sustainable means to support our food production systems and providing technology that's accessible to all the world's farmers.

Thank you. (*Applause*) That was Giles E.D. Oldroyd at TED's Countdown Dilemma Series on the future of food in 2024. If you're curious about Ted's curation, find out more at ted.com slash curationguidelines. And that's it for today's show. TED Talks Daily is part of the TED Audio Collective.

This episode was produced and edited by our team, Martha Estefanos, Oliver Friedman, Brian Green, Lucy Little, Alejandra Salazar, and Tonsika Sarmarnivon. It was mixed by Christopher Fazy-Bogan, additional additional support from Emma Tobner and Daniela Balarezzo. I'm Elise Huw. I'll be back tomorrow with a fresh idea for your feed. Thanks for listening. From fleet management to flexible truck rentals to technology solutions, at Enterprise Mobility,

we help businesses find the right mobility solutions so they can find new opportunities. Because if your business is on the road, we want to make sure it's on the road to success. Enterprise Mobility, moving you moves the world.