Students' color-changing tomato reaches national contest finals

An invention developed by two Cornell doctoral students that turns engineered tomato plants a vivid red when soil nitrogen levels are low has been named a finalist in the national Collegiate Inventors Competition.

The RedAlert Living Sensors, created by Jacob Belding and Ava Forystek, is one of five finalists contending in the graduate student category of the competition, run by the National Inventors Hall of Fame.

Developed through the National Science Foundation's Center for Research on Programmable Plant Systems(CROPPS), the students' genetically modified sensor plants could one day help gardeners, farmers and hydroponic growers assess if their plants need more nitrogen. When the sentinel plants turn red, growers may then target where and when to fertilize. Farmers currently apply up to 50% more nitrogen than needed, which has led to run-off that pollutes groundwater and lakes, where it promotes harmful algae blooms.

The two students will present their invention in a "Shark Tank" style pitch to a panel of judges composed of some of the most influential inventors and invention experts in the country on Oct. 16 in Washington, D.C. The judges, including National Inventors Hall of Fame inductees and U.S. Patent and Trademark Office officials, will select two top teams and a people's choice award, each of which will receive cash prizes and a form that fast-tracks patent acquisition. An undergraduate contest will also take place.

Currently, one common method for detecting nitrogen deficiencies in plants assesses yellowing and wilting in leaves. By the time leaves turn yellow, the plant is already stressed from low nutrients.

"We like to use the analogy of a dog that whines when it's hungry," said Forystek, who works in the lab of Neil Mattson, professor in the school of Integrative Plant Science Horticulture Section in the College of Agriculture and Life Sciences. "It would be kind of ridiculous to wait until you feel its ribs to feed it."

The RedAlert Living Sensors take advantage of a native pathway where the plant detects nitrogen around its roots and translates those signals to the rest of the plant. The tomato plants used in the project were genetically modified to express a red pigment when root zone nitrogen is low. Shades of redness also reflect varying gradients of available soil nitrogen.

"We're taking a signal from the roots where the plant first notices there's not enough nitrogen in the soil and it translates that into visible pigment, so we can see on the plant that it is hungry for nitrogen, but it's not already starving," said Belding, a member of the lab of Abraham Stroock, the Gordon L. Dibble '50 Professor in the Smith School of Chemical and Biomolecular Engineering in Cornell Engineering.

Stroock and Mattson are team advisers, along with Margaret Frank, associate professor in the School of Integrative Plant Science, Plant Biology Section, in CALS, who first came up with the idea for the nitrogen-sensing plants.

One day, farmers may be able to plant tomato sentinel seeds in their corn fields to monitor nitrogen levels; home gardeners might use them in their backyards; and hydroponic growers might employ them to ensure their systems' plumbing is distributing the necessary nutrients.

"It's amazing to see this technology move from our research labs into the world where it can positively impact sustainable agriculture," Frank said.

In large field systems, tractors already equipped with cameras that read infrared and visible wavelengths could survey crop fields for interspersed sentinel plants, to inform farmers of nitrogen needs. The team is exploring the development of a smartphone app that would directly correlate sensor plant leaf colors to root zone nitrogen levels. In this way, small farmers could monitor their fields with their phones.

"It's kind of a democratization of these smart agriculture tools that have seen a lot of popularity in the past decade, but are mostly restricted to pretty sophisticated, expensive systems, with highly technically trained operators," Belding said. "This could be a smart ag device that is affordable and can be easily used by even a home gardener."

Initial work on the project was done by Brandon Williams, M.S. '23, Ph.D. '25, a former member of Frank's lab, and Yinan Wu, a former postdoctoral researcher in the lab of Sijin Li, assistant professor in the Smith School of Chemical and Biomolecular Engineering in Cornell Engineering. Forystek has helped Belding and other engineers work in the greenhouses and in better understanding challenges of field applications.