Jacob Belding and Ava Forystek, Ph.D. students of Cornell University, Ithaca, NY, USA, have developed genetically engineered tomato plants that turn vivid red when the soil nitrogen levels are low. Their so called RedAlert Living Sensors are expected to help gardeners and farmers to detect nutrient deficiencies early, rather than waiting for the typical late-stage yellowing and wilting of leaves and plant starvation. Currently farmers 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.
Using the plant’s native nitrogen-sensing pathways that detect nitrogen levels around the roots and transmit the signal to the rest of the plant. The new tomatoes produce red pigments of varying intensity to indicate nitrogen levels in the root zone.
The project is a finalist in the Collegiate Inventors Competition hosted by the National Inventors Hall of Fame.
- Krishna Ramanujan, Students’ color-changing tomato reaches national contest finals, Cornell Chronicle September 29, 2025. (accessed October 8, 2025)
