DARPA has launched a new surveillance program which plans to use genetically engineered plant as battlefield surveillance sensors. DARPA’s new Advanced Plant Technologies (APT) program looks to seemingly simple plants as the next generation of intelligence gatherers. Traditional sensors are not always optimal for obtaining timely, accurate information as national security landscape has grown far more complex and the challenges of monitoring distributed activity far more complicated, says DARPA.
DARPA’s vision for APT is to harness plants’ natural mechanisms for sensing and responding to environmental stimuli and extend them to detect the presence of certain chemicals, pathogens, radiation, and even electromagnetic signals. APT aims to modify the genomes of plants in order to program in these specific types of sensing and trigger discreet response mechanisms in the presence of relevant stimuli, and do so in a way that does not compromise the plants’ ability to thrive.
The program will pursue technologies to engineer robust, plant-based sensors that are self-sustaining in their environment and can be remotely monitored using existing hardware. The technology have already been experimented by many researchers. Engineers from MIT have already demonstrated turning spinach plants into sensors that can soak up explosive molecules from groundwater, detect their presence and then transmit that information to a handheld device. The plants were designed to detect nitroaromatics, which are often used in landmines and other explosives. When one of these chemicals is present in the groundwater sampled naturally by the plant, carbon nanotubes embedded in the plant leaves emit a fluorescent signal that can be read with an infrared camera.
The development from a team at MIT is said to be one of the first demonstrations of engineering electronic systems into plants, an approach dubbed plant nanobionics. “The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions,” said Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the leader of the research team.
If the program is successful, it will deliver a new sensing platform that is energy independent, robust, stealthy, and easily distributed. Such sensors could find application outside of the military too, making it possible, for instance, for communities to safely identify landmines or unexploded ordinance leftover from past conflicts or testing grounds. To meet this demand, the Department of Defense invests heavily in the development of powerful electronic and mechanical sensors, and in the manpower to maintain and operate those sensors.
Plants as sensors
Modern plant biotechnology holds significant promise for addressing a range of Department of Defense (DoD) needs; plants are easily deployed, self-powering, and ubiquitous in the environment, and the combination of these native abilities with specifically engineered sense-and-report traits will produce sensors occupying new and unique operational spaces.
“Plants are highly attuned to their environments and naturally manifest physiological responses to basic stimuli such as light and temperature, but also in some cases to touch, chemicals, pests, and pathogens,” said Blake Bextine, the DARPA Program Manager for APT.
“Emerging molecular and modeling techniques may make it possible to reprogram these detection and reporting capabilities for a wide range of stimuli, which would not only open up new intelligence streams, but also reduce the personnel risks and costs associated with traditional sensors.”
APT aims to go far beyond current practice, which tends to pursue only a minimal number of modifications. DARPA’s goal is to modify multiple and complex traits to give plants new capabilities that enable them to sense and report on numerous stimuli.
To succeed, however, the program must also address how modified plants allocate internal resources and compete in natural environments. Past experiments of this type have reduced the fitness of modified plants by siphoning resources needed to sustain the plants. APT will seek to improve how plants collect and distribute resources, and optimize their fitness so that modified plants thrive despite anticipated interactions with natural stressors such as microbes, animals, insects, and other plants.
The goal of the APT program is to control and direct plant physiology to detect chemical, biological, radiological, and/or nuclear threats, as well as electromagnetic signals. Plant sensors developed under the program will sense specific stimuli and report these signals with a remotely recognized phenotype (e.g., modified reflectance, morphology, phenology, etc.).
Plant sensor platforms developed in the APT program must be based on non-model plants that have the ability to persist for long periods without being affected by normal variation in outdoor conditions (e.g., climate, native biota).
The long-term success of engineered plant sensors requires the ability to ensure plant survivability for months or years in a
natural environment subject to stresses not present in a laboratory environment. Meeting both the sensor and survivability technical goals of the APT program will require a combination of plant genomics emerging technologies, precision gene editing tools, and novel methods for engineering new sensing capabilities and physiological responses. Proposing teams should include experts in diverse fields including plant physiology, gene editing, biochemistry, modelling, phenotyping, remote sensing, and plant ecology.
Initial work on the program will take place in contained laboratory and greenhouse facilities, as well as simulated natural environments, and adhere to all applicable federal regulations with additional oversight from institutional biosafety committees. If the research is successful, later-phase field trials would take place under the auspices of the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service following all standard protocols for plant biosafety.
APT will rely on existing ground-, air-, and space-based technology to remotely monitor plant reporting. Such systems are already capable of measuring plants’ temperature, chemical composition, reflectance, and body plan, among other qualities, from a standoff distance. It will be up to the researchers proposing to APT to determine which plants, stimuli, and modifications to pursue as proofs of concept.
To accomplish the above program goals, proposers will leverage state-of-the-art plant gene alteration techniques towards three specific and complementary technical objectives:
Phase1: Identify, test, and integrate genetic components for plant sensing and reporting. Proposers will engineer sense-and-report traits into plants by designing and engineering the appropriate gene sequences and pathways for sensor and signal transduction components and for the production of response phenotypes. Modified plant sensors must persist for the life of the plant without degrading the environment, so plants must also be designed to optimize their ecological interactions.
Phase 2: Tailor plant resource collection and allocation to support sense-and-report traits. Proposers will modify the genetics of the plant chassis to ensure sensing and reporting capabilities by collecting energy, nutrients, water, and other potentially limiting substrates that negatively affect the plant’s ability to sense and report target stimuli.
Phase3: Ensure long-term sense-and-report capability by engineering plants to be robust in intended environments. Proposers will modify the plant chassis for robustness in the environment, by enhancing interactions with other species of plants, insects, and microbes, without disruption to native ecological communities. The targeted stimulus modalities, response phenotypes, and other innovative traits must be clearly identified in the proposal and the choices sufficiently aligned with the overall program goal of producing a robust plant-based sensor platform.
“Advanced Plant Technologies is a synthetic biology program at heart, and as with DARPA’s other work in that space, our goal is to develop an efficient, iterative system for designing, building, and testing models so that we end up with a readily adaptable platform capability that can be applied to a wide range of scenarios,” said Bextine.
UTIA Awarded $7.5 Million to Lead Study of Potatoes as Sentinel Plants
Researchers with the University of Tennessee Institute of Agriculture will lead a new effort worth up to $7.5 million to use plants to detect environmental threats to deployed troops and help protect civilians living in post-conflict settings. The goal is to innovate a new, revolutionary sensor platform.
Awarded by the U.S. Defense Advanced Research Projects Agency, also known as DARPA, under its Advanced Plant Technologies program, the 4-year effort will combine the expertise of plant biologists, biochemists and engineers. Researchers at UT and the Massachusetts Institute of Technology will work to modify potato plants to detect and report potential threats such as nerve agents, radiation and plant pathogens.
Neal Stewart, a professor of plant sciences in the UT Herbert College of Agriculture who also holds the endowed Racheff Chair of Excellence in Plant Molecular Genetics, will serve as the lead principal investigator of the effort. Stewart is well known in scientific circles for his efforts to use genetic markers to develop sentinel plants that can detect environmental problems or nutritional deficiencies in efforts to help farmers increase yields. He is also co-director of the recently formed UTIA Center for Agricultural Synthetic Biology. CASB is the first university research facility dedicated to the use of gene editing and other synthetic biology methods to endow radical improvements to the sustainability of crop agriculture.
Scott Lenaghan, an assistant professor in the Department of Food Science who also holds an adjunct position in the UT Department of Mechanical, Aerospace and Biomedical Engineering is co-director of the CASB. He will serve as the project and overall team lead for this DARPA effort.
The work at UT will mainly focus on engineering of plants for sensing and reporting environmental stimuli to make “talking plants.” Stewart says the potato plant was chosen for this study because it is the easiest crop plant for engineering both the main genome and the one housed in chloroplasts. “It’s got all the engineering and growth traits that will make for an effective ‘talking plant’,” says Stewart. Our preliminary research convinced us the potato is the right crop for this ‘Phytosensors 2.0’ project. Potato even makes a convenient storage organ—the tuber—which is the plant’s ‘battery’.”
Other faculty involved in the project at UT include Feng Chen, a professor of genomics in the Department of Plant Sciences; Tessa Burch-Smith, an assistant professor in the Department of Biochemistry and Cellular and Molecular Biology; and Howard Hall, a professor in the Department of Nuclear Engineering. Their contributions range from engineering insect resistance to root-to-shoot communication, to radiation experiments, all designed to support development of effective plant sensors that can survive and thrive.
In partnership with UT, are professors Chris Voigt and Angela Belcher with the Department of Biological Engineering at MIT. They bring world-class expertise and capabilities of synthetic biology to the team. John DiBenedetto, a Department of Energy scientist, will support the project with equipment and expertise in sensing equipment. He and Stewart collaborated in some of the first published phytosensor projects.
While the focus of this project is the development of plant sensors for the military, Stewart hopes that advances gained through this and other efforts in synthetic agricultural biology will eventually result in crops that can tell farmers exactly what, where and when they have problems with pests, water and nutrients in their fields. “This project is very exciting with regards to translating our findings into plant ‘devices’ that can help farmers,” he says.