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Last week the Internet lit up with news of spinach plants that could send emails. The culmination of a body of scientific research had enabled the plants to sense materials associated with explosives in the soil, and to transmit this information via electronic mail.
It sent the Twittersphere into raptures, with the subject sparking countless bad jokes about Spam and ‘you’ve got kale’. The fact that the research dated back to 2016 seemed to go over most people’s heads, but it also begged the question: if this is what MIT was able to do with plants then, what are they able to do today?
Photo Credit: Bryce Vickmark
Professor Michael Strano’s lab at MIT is responsible for the paper on the emailing spinach. He works with plants and nanotechnology in a new field of research known as Plant Nanobionics, a study that uses nanoparticles to impart functions onto living plants. The 2016 paper on emailing spinach proved a seminal work that has seen a new, incredibly exciting field open up.
“When that paper came out, I had videos and demonstrations, it was pretty out there, but it has started a new field of research internationally,” says Strano.
“Just last December, we made plants, including spinach and rice, which can detect arsenic in the water. It operates in the same way and you can make one of the most sensitive detectors of arsenic in groundwater. This is becoming an area of technology whereby we build on to plants. The plants become machines; it’s a really fascinating field of research."
Photo Credit Bryce Vickmark
Anyone who keeps house plants or tends their own garden may feel that their plants have a certain intelligence, however, it’s not something professor Strano is particularly willing to discuss.
“You’ve got to be careful about using the word ‘intelligence’,” he says. “For decades there was a debate about whether plants have behaviour or not. Do they have psychology? They don’t have a central nervous system, so we normally reserve those words for things that have a brain. But the arguments can go either way, depending on who you are. To some extent, you may ask ‘what is intelligence’? Plants are living, they take in information, they respond to external stimuli, they do have algorithms, but they can’t pass a Turing test, so you could never confuse them for a human.”
Harnessing plants' innate abilities and imparting new functions on them is the focus of Strano’s work, and it is a brave new world of enhanced biological life. One that has real-world applications today.
Arsenic is a big problem for growing rice where natural aquifers are contaminated with it. It’s hard to detect in trace amounts, however, plants are great at detecting it.
“We made this plant, we tested it, and it turns out it’s the best detector for trace amounts of arsenic in the water. It sits there transpiring water, activating nanoparticles in the leaves and sending an infrared signal to a user’s cell phone."
Nanotechnology can make a wide variety of particles with different properties. So Strano can put very small nanoparticles into something and make it magnetic, he can make plastics become electronics, and can even make a living leaf become a conductor of electricity. Gold nanoparticles, if put into glass, can take on colour. They are somewhat like ingredients that are baked into a cake, allowing it to behave differently than it would otherwise. And it is MIT, and Strano’s lab in particular, that is leading the way.
Glowing Watercress Photo Credit Seonyeong Kwak
“We made a big breakthrough at MIT, which was very surprising. We developed a theory that could put nanoparticles deep inside the plant. We figured out the rules for a plant to accept these nanoparticles. A plant is a machine, it generates its own energy, it stores that energy, it pumps water from the ground, it self-repairs… This started an area of research that begs the question ‘what can we get a plant to do?’
“Can you replace electronics components with living plants? There are huge benefits to that, energy benefits, sustainability benefits, reduced carbon footprint, recycling benefits, safer for the environment...," says Strano.
It may sound like science fiction but it is very real. Strano can point to his laboratory, where they have created a light-emitting plant – turning a plant into a lamp. They have created the brightest living thing.
“We have been working on light-emitting plants and it is going very well, with the next generation about to arrive. The idea is to take a living thing that can take some of its energy and radiate it as chemiluminescence. We demonstrated the first one in 2019, and now we are making the plant radiate longer and brighter. If we can get to 12 hours, then you can have the plant recharge during the day and illuminate at night."
Fifty years ago we were moving into the age of plastics and today, despite our best efforts at recycling, the vast majority of polymer plastics end up in landfill - 50 million metric tonnes each year. With all of that goes all the energy and all the solvents, the environmental impact is so much more than just the tonnage that goes in the ground. If this technology had existed 50 years ago, our planet might look very different today.
In the near term, there is huge potential for this technology in big agriculture and urban farming – sensors for agriculture and the sector has taken notice. The Singapore government helped Strano set up a satellite lab, which he did through MIT’s Smart Program, to create tools that can revolutionise agriculture.
And it would seem that plants have a lot to say if you know how to listen to them. Just a couple of months ago the lab published a big paper showing that you can intercept the signals that are inside a living plant. While a plant is alive they are sending packets of chemicals, communicating with themselves. If you cut open basil, you’ll smell the volatiles that are produced, the plant is constantly talking with itself.
“At MIT we’ve made a variety of sensors that can detect things like plant hormones, signalling pathways, in real-time. We can take a living plant, put a small amount of nanoparticles in it and with something like a cell phone you can see the plant tell you what kind of stress it’s experiencing. If an insect bites a plant, you can actually see on your phone, the stress response within minutes and these signals tell us the type of stress, there’s a language within the plant. It’s really exciting."
“If you infect a plant with harmful bacteria, if you shine too much light on a plant if its temperature is not correct... I’m not going to weigh in on whether plants are intelligent or not, but we have found language, which means farmers can get information about their crops that they couldn’t get before."
In theory, farmers would know the first time an insect that’s a pest bites a plant, long before they had yield loss. It turns out plants are very sensitive detectors of the environment around them. They know long before we do that there’s a drought coming, that it’s too hot or that they need more nutrients. Trained farmers can look at a leaf and see there’s a nitrogen deficiency, but by then the plant is dead, they’ve had 30% yield loss. That’s the attraction for agriculture - turning the plant itself into a sensor as an early warning system.
Crucially, plants modified with nanoparticles do not replicate. Everyone is familiar with the fact that GMO crops spread and reproduce easily. You can have a particular crop in one field but pretty soon, you find it down the road, in another field. It’s a major part of the public’s opposition to the concept.
As to the reason for Strano’s research trending on Twitter five years after publishing, the professor is at a loss to explain it. People have been stuck at home for a long time because of the pandemic, they feel in many cases, disconnected from the natural world. Perhaps the idea of plants trying to communicate with us was something we needed to hear.
“I don’t control the Internet so I really don’t know what happened,” he says. “I think there are these algorithms and people tweet and retweet, I think a million people wanted to tweet a joke about a plant sending an email. You can look at hundreds of the tweets people are making really bad jokes."
You wonder, in the future, will plants appreciate those jokes or will they just face-palm?
