What if a plant facing attack from insects or disease could send out an early-warning signal by, say, emitting a glow or turning its leaves purple?
A handful of startups are using gene editing and sensors to do just that, programming plants to "tell" farmers when they are under stress before visible symptoms appear.
The idea is that if plants can show they are struggling earlier, farmers can take targeted action to nip problems in the bud. Instead of spraying huge swaths of farmland with fungicides and herbicides to stave off pests and disease, farmers can treat small sections of their crop as needed, reducing reliance on chemicals that eventually leach into soil, waterways and drinking water.
"Plants naturally give us visible information about their physiology in a number of ways -- wilting, for example," says Alexander Jones, a professor at the University of Cambridge who focuses on plant biology. "But these signs can come too late for us to act."
Shely Aronov, chief executive of California startup InnerPlant, explains that when plants are attacked they start to activate genes to protect themselves. "Those reactions happen very fast and they're different, depending on the stress," she says.
InnerPlant's technology works by engineering plants at the DNA level. Those traits are then passed down to the seeds they produce. "It's kind of like adding a line of code, so that once the plant is reacting to, say, fungal pressure, it's going to start producing a protein that creates an optical signal," says Aronov.
In the case of InnerPlant, that optical signal is a glow given off by the plant that is invisible to the human eye but detectable by tractors with cameras in the field, drones or satellites.
InnerPlant is backed by farming-equipment giant Deere, which invested in the startup in 2022 and has equipped its John Deere smart tractors with cameras that can detect the signals being given off by the plants.
"The plant being able to tell you itself what is going on versus you having to look for visual effects was very compelling," says Dan Leibfried, vice president of marketing and shared services at Deere. "InnerPlant is definitely one of those disruptive technologies that I fundamentally believe will transform the industry over time."
Elsewhere, Indiana-based Insignum AgTech is designing corn crops whose leaves turn purple in reaction to fungal diseases and pests. "When you see disease it's too late," says Chief Executive Kyle Mohler.
Mohler hails from a farming family who grow corn and soybeans. He says that like most farmers, his family used to spray chemicals on every acre every year, whether the crop needed it or not, giving him the idea that more needed to be done in terms of dedicated crop protection.
Insignum uses gene editing to "switch on" traits already within the plant's DNA. "Plants have the ability to respond to disease within minutes from where it starts, but we [the farmers] just do not know for days or weeks," says Mohler, adding that Insignum's technology allows farmers to react much more quickly.
Hurdles await
Some scientists say plants designed to emit early stress signals could provide a productivity boost to farmers battling climate and environmental pressures.
"We're looking at both population growth and changes in global temperatures having impacts on agricultural productivity over the next century, so all of these technologies can help eke out more yield, as growing conditions get stressed in different ways," says Sean Cutler, plant biology professor at the University of California, Riverside, and a co-founder of Living Sensors, which uses a technology similar to InnerPlant's to detect forever chemicals, known as PFAS, in soil.
Stopping issues such as herbicide drift, where farmers spray chemicals onto their land and through wind it moves miles away and damages other crops, would be another advantage, he says.
How quickly these plants work their way into the wider food chain, however, remains a question. Most of the technologies are still in the testing phase, and will require regulatory approval thereafter.
There are other hurdles that could hinder adoption. Some markets, like the European Union, ban the sale of food that has significant edits to its genome like the kind designed by InnerPlant and Insignum. In the U.S., there are some gene-edited crops on the market but many consumers remain wary, worried that genetically modified or edited foods might carry health risks. Adopting new plants also could be costly for farmers, especially if they have to invest in new technologies such as drones and satellites or tractors with cameras.
High costs, slow approval processes and outright bans to using these kinds of technology "makes it tough for these sorts of biology companies to get off the ground and thrive," says Jones, the University of Cambridge professor. Still, he says he believes "the drawbacks are few and minor and no longer justify the legal and policy roadblocks."
Alternative approaches
Some scientists say that if the goal is to boost agricultural output and restore the environment, the emphasis should be on soil health, not genetically modified plants.
"Genetically modifying crops for this purpose means altering future generations of plants to come, and we're not certain what the repercussions might be down the line," says Praveena Sridhar, chief science and technology officer at Save Soil, a nonprofit focused on improving soil health.
Technologies such as photonic monitoring, where light particles are monitored to track plant health or stresses, and improved integrated pest-management systems can deliver the same benefits as genetically modified crops without the unknown long-term risks, Sridhar says. "We can reduce chemical inputs, restore soil health and improve yields through these alternative approaches," she says.
Meanwhile, companies such as British startup Viridys Bio are trying to create biological sensors external to plants to detect when they're in stress. The company's technology stems from sensors used to detect land mines in war zones by looking for explosive residues. The company is rewiring those sensors to detect small molecules released in the air by plants known as volatiles, which are especially useful in greenhouses.
"When an aphid nibbles on a leaf, the volatile release attracts ladybirds in a very simplistic sense," says Stuart Dixon, co-founder of the early-stage company. "If you can tap in to that language, we felt that we could turn that invisible cue into something that was visible," he says.
Dixon says that the technologies should be able to help growers react to issues more quickly and accurately, adding that most crop-protection chemicals rarely hit their intended target.
"Most of it runs off, and obviously that's really damaging," he says.
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