Scientists at Nanyang Technological University (NTU) Singapore have developed a method to boost a plant's natural immune system by modifying its immune receptors. The research used Arabidopsis thaliana, a small flowering plant often used as a model in plant biology studies, which belongs to the same family as common vegetables like chye sim and kai lan. In experiments, plants with the enhanced immune system showed about 53% less bacterial growth compared to normal plants, as measured in lab tests. Importantly, the improved immune response did not hinder the plants' normal growth. The study, published in Science Advances, used synthetic protein engineering to adjust immune receptors, helping plants better fight disease-causing microbes. The researchers have also applied for patents on two technologies through NTUitive, the university's innovation company. This research has potential applications in agriculture, especially in indoor and vertical farming, where crops are grown closely together, increasing the risk of disease spread. The scientists are now exploring ways to apply the same principle to food crops already in use, including the development of "designer stimulants" that could be applied directly to plants to improve their immunity. The goal is to make crops more resilient to diseases without altering their natural growth patterns. Plants have receptors on their cell surfaces that detect harmful bacteria and other microbes. The NTU team discovered that arranging these receptors in the right numbers can put the plant in a higher state of alert, allowing it to recognize threats more effectively. However, overcrowding the receptors led to a strong but short-lived response, as the receptors couldn't be replaced efficiently. "It's like having more guards at a watchtower," explained Miao Yansong, the lead researcher. "The right number helps detect intruders quickly, but too many can cause problems." The study focused on a specific immune receptor called flagellin sensing 2 (FLS2), which detects flagellin, a protein found in many bacteria. Using advanced imaging and protein engineering, the researchers tested various groupings of FLS2 and its partner receptors. They found that an arrangement of two FLS2 receptors and two partner receptors provided the best balance: it strengthened immune signals while allowing receptors to be replaced normally after use. While the experiments used Arabidopsis, the findings could be adapted to leafy vegetables like Chinese cabbage, chye sim, and kale. However, more research is needed to tailor the approach for each type of crop before it can be used commercially. The researchers are now focusing on leafy vegetables and other high-value crops suited for indoor farming. Miao has filed patent applications covering two key technologies. The first is a method to control how receptors group together on plant cells, enabling a stronger and more sustained immune response. The second is a live-cell imaging platform that allows scientists to count how many receptors are assembled on a plant cell's surface. These tools help researchers study and improve immune systems in plants. While the initial study used genetic modification, the team is now exploring alternatives like additives that could be applied directly to existing crops in the field. Miao said the findings open multiple pathways for application, including improved seeds and direct crop treatments. The team is now working to scale up the technology for use in food crops grown in indoor environments and will test its effectiveness against various pathogens under real-world conditions.