Horticultural scientist Kevin Folta is decoding plants’ responses to light across the spectrum By Cindy Spence
Kevin Folta is the Dr. Dolittle of the plant kingdom. Folta is interpreting a new language, spoken between the sun and the Earth’s plants — where blue means one thing, red another — so that one day farmers can use light to give plants instructions: grow faster, bigger, more nutritiously.
Through this language of light he coaxes more antioxidants from kale, better flavor from strawberries. One day, he says, plants will come with a recipe for light. Much as farmers today know to use this much water or that much fertilizer, one day they will have instructions for light exposure.
“You may have a plant under a blue light in the morning, a green light in the afternoon and a far-red light overnight, with a two-hour dark break before the blue light comes on again,” says Folta, chair of the Department of Horticultural Sciences in UF’s Institute of Food and Agricultural Sciences. “We can put together combinations of light in a prescription that will change how the plant grows and develops.”
What’s more, those instructions may extend beyond harvest, to the lights in the produce section at the supermarket or in your refrigerator at home.
“Our hope is that we could make food products last longer, especially since 40 to 50 percent of food that’s harvested in the U.S. goes to waste because of after-harvest decay,” Folta says.
Right now, the work is in the early stages, as scientists try to determine how plants respond to different light exposures across the spectrum. Plants possess many light-sensing receptors, like 15 eyes, each one able to “see” a different part of the spectrum. The plant adapts as its receptors sense the presence of each color.
This goes way beyond photosynthesis.
Light visible to the human eye represents just a fraction of the light spectrum. From infrared on one end to ultraviolet at the opposite end, much of the spectrum is invisible to humans, but not to plants.
The colors in the spectrum of light give a plant information — the time of day, the season, its proximity to its neighbors — and the plant uses the information to change its gene expression and growth habits. Changing the light — the information — changes the way a plant grows and develops.
So far, Folta says, experiments have shown that it is possible to affect the size of leaves and stems, important factors in growing a crop like spinach or lettuce. With Assistant Professor Thomas Colquhoun of the environmental horticulture department, they have shown that light also affects flavor and aroma. Going forward they will examine light effects on nutritional content and enhancing nutriceutical compounds with potential roles in cancer prevention.
“We’re really just learning what we can control,” Folta says. “We’re just starting to understand how different parts of the spectrum affect different aspects of plant growth, development and nutritional content.”
Fridge of the Future
Folta began working with plant genes that were affected by light in his undergraduate years and remembers building light arrays from parts bought on eBay and empty shipping boxes. The equipment needed made the research expensive.
“For a long time, we had to build our own arrays, do our own electronics,” says Folta, who remembers threading tiny LEDs — light-emitting diodes — through the holes in pipette shipping boxes.
Today, the cost of LEDs is dropping, and companies now make custom fixtures that can replace Folta’s homemade contraptions of years past.
“We can now realistically use and deploy this technology at an industrial level,” Folta says.
The research has advanced to the point that appliance companies are interested in redesigning refrigerator lights, perhaps even using ultraviolet light to provide an anti-microbial environment. The refrigerator of the future, Folta says, could operate the opposite of today’s refrigerator: instead of the light going on when you reach in for a cold snack, it would go off. The light would go on again, perhaps in different combinations in different compartments, when you close the door.
Light conditions, Folta says, could help retain the nutritional value that is already in a vegetable or fruit in storage.
Even more exciting, lights could be used to amp up the nutritional value.
“We’re testing now how to get plants to produce more beneficial compounds like folate or vitamin C, or important anti-cancer compounds,” Folta says.
The technology was tested using Arabidopsis thaliana, horticulture’s version of a white lab rat, on a grant from the National Science Foundation. Folta’s lab moved up the food chain from there to test kale, strawberries, blueberries and tomatoes. In kale, sequential treatments of darkness, blue light, red and far-red light produced variations in growth, development and nutritional value.
Colquhoun and Folta’s labs also showed that specific light treatments altered fragrance and flavor of blueberries, strawberries and tomatoes. The key is figuring out which wavelengths to use at which intensity, duration and direction. Once the combinations are worked out, a small farmer with a relatively simple light array could use them to add value to a crop by changing its color, size or nutritional content.
“This allows us to be the plant whisperers,” Folta says. “It allows us to tell the plant how to behave, what we want and how to produce it.”
Folta calls the resulting plants EMOs — environmentally modified organisms — in contrast with GMOs — genetically modified organisms, which have become a flashpoint in agriculture globally.
As a scientist, Folta doesn’t understand opposition to modifying plants by methods that have been proven to be safe and effective. He argues — on dozens of radio programs and online forums annually — that from the moment humans began cultivating crops 12,000 years ago, they started changing them, cross-breeding to enhance desirable traits, and today’s food crops only remotely resemble their genetic forbears. One online segment last year on the Huffington Post drew more than 500 comments in an hour. If people only understood GMO technology, he thinks, they would embrace it.
So far, Folta says, no one objects to using lights to tinker with plants, even though the changes are dramatic and sometimes quite unusual.
“We’re changing plant gene expression in a way that never occurs naturally. We create a recipe of lights that, when we turn on that switch, there’s never been a plant that has seen that before,” he says. “It’s way, way, way more involved than genetic modification, but nobody really cares.”
As a teacher, Folta says, he takes it seriously when he hears people make claims that are not scientifically accurate. He says it’s his duty as a scientist to communicate facts — with kindness — to offset a growing anti-science bias he fears will lead to lost opportunities to use beneficial technologies. Lights are only one tool; using all the tools available will be the key to feeding the planet.
Folta predicts the next wave of genetic modification — he calls it GMO 2.0 — will be crops that provide more nutrition with less impact to the environment. And genetic modification may be the best hope for keeping a glass of orange juice on the breakfast tables of Floridians. Beleaguered citrus growers have struggled for years with diseases like canker and citrus greening. Several trials using plant defense genes to impart bacterial resistance to citrus plants look promising, Folta says, and may play a key role in Florida continuing to be known for citrus.
“These are the same genes and same gene products people consume every time they eat a fruit or vegetable, so it shouldn’t be something they’re afraid of,” Folta says, “and when they realize that, they’re not afraid.”
Folta began his career at UF working on strawberry genomics, promoting open access to discoveries as they were made and playing a key role in an international research effort. Thanks to that synergy, in 2010, the strawberry was the 12th plant genome to be sequenced. Today, thousands of plant genomes are sequenced.
Folta hopes to see the work with light modification of plants take off in the same, collegial way, with scientists sharing information between labs to speed up the pace of discovery. The potential exceeds even Earth’s boundaries, he says.
“This technology could be used in outer space. LED lights are very portable and last a long time, 50,000 hours,” says Folta, who is only one UF researcher with his sights on space. Colleagues Anna-Lisa Paul and Rob Ferl have sent plants into space five times to learn more about how plants can support future space missions. The LED experiments may be the contribution of Folta’s lab to such missions.
“If you’re using lights in space to grow crops,” Folta says, “you don’t want to be changing light bulbs.”
So far, from farmers to hobbyists, the people he speaks to are excited about the potential of gardening with LEDs.
“It brings to light how we think about our food,” Folta says. “When I talk about environmental modification, with lights, people ask ‘Where can I get it, can I set it up in my house?’”
So the plant whisperer keeps working on new light recipes.
Kevin Folta, Associate Professor and Chair of Horticultural Sciences