ITHACA, N.Y. – Bioengineered tomato plants can now alert farmers to low soil nitrogen levels with leaves that turn a vivid red, thanks to multidisciplinary collaboration between Cornell University researchers. The invention, dubbed RedAlert Living Sensors, was created by doctoral students Jacob Belding and Ava Forystek and developed through the National Science Foundation’s Center for Research on Programmable Plant Systems.

While the exact mechanism of the invention cannot be revealed because the researchers are in the process of filing for intellectual property protections, Belding provided a high-level explanation of how the Living Sensors work.

“Plants natively have hormone signaling systems to coordinate their needs for different nutrients, much in the same way that animals such as humans signal hunger with hormones,” he said. “These chemical signals are mobile within the plant, traveling between roots and shoots via the vasculature. This means that information on what is happening nutrient-wise near the roots is available in the aboveground part of the plant in the form of these signals.”

To observe plants’ needs for nutrients, an extra element was added – a naturally occurring red pigment. RedAlert Living Sensors translate information from hormone signals – like if there’s enough nitrogen nearby the roots and if not, how severe the deficiency is – into molecules of a red pigment. The leaves of the plants gradually turn red depending on how much nitrogen is present in the soil.

“Our hope is that adoption of this invention will help growers to have more and better-quality information to work with when deciding on nitrogen management strategy for their operation. Thanks to the horticulturists on our team, we understand that each operation has its own needs, and we hope to empower further refinement of their strategies by providing a low-cost and easy-to-use tool for learning about what the crop is actually experiencing around its roots,” Belding said. “We and the growers we’ve talked to are unsatisfied with existing nitrogen sensing technologies and would like to see RedAlert make high quality information accessible to every operation of any scale.”

Others see value in the invention, too. The two doctoral students were chosen to present at the national Collegiate Inventors Competition, which took place in Washington, D.C. in October 2025. The competition is run by the National Inventors Hall of Fame and was judged by National Inventors Hall of Fame inductees and U.S. Patent and Trademark Office officials.

Belding relayed that while it was nerve-wracking to present to impressive inventors, the presentation went well. The team received the second-place prize for graduate student inventors, taking home $5,000 and a patent acceleration certificate to fast-track their patent application.

Belding added that a similar system could be engineered into any dicot species based on the team’s current understanding of the biology. However, he addeds that it’s not necessary for a RedAlert version of every crop to be made in order for the invention to be useful in different applications.

“(We) envision a ‘sentinel’ model, in which some RedAlert plants are planted alongside or interspersed with your main crop,” he explained.

Still, there are some limitations to this model. For example, RedAlert would not work with maize, as maize is a monocot and its nitrogen needs are enormous. A tomato sentinel plant would detect no issue with an intermediate nitrogen level that might be plenty for tomato but still cause suboptimal yield in maize, Belding said. He noted that the research group has some potential solutions in the works for addressing this issue.

“(We) believe our research is important for the benefits it could bring in providing greater access to smart agriculture tools and in reducing nitrogen waste,” Belding said. “Nitrogen waste has many harmful downstream consequences, including immense ecological harm to our waterways and dangerous contamination of well water in rural areas, and we would love to see these problems reduced.”

Belding shared that his research efforts are currently focused on continuing the characterization of RedAlert and integrating the system with modern computer vision and robotic capabilities. Forystek’s research work is focused on developing and testing optimized growing standards for the emerging market of greenhouse-grown teen leaf lettuce.