Colorado State University biologists have been awarded a Defense Advanced Research Projects Agency grant to examine the possibility of genetically engineering plants to rapidly lose their green color in response to biological or chemical weapons. The scientists’ goal is to develop simple and affordable plants that can quickly sense deadly agents and warn the public of danger.
"The increasing threat of terrorism presents a great need for simple and robust detectors of harmful biological or chemical agents," said biology professor and principal investigator June Medford. "Plants have evolved elaborate mechanisms to sense and respond to their environment. By using advanced biotechnology methods, we believe we can genetically engineer these mechanisms to produce plant sentinels that can provide an almost immediate warning of biological or chemical agents."
Medford and co-principal investigator Anireddy Reddy are working on phase one of the 18-month DARPA grant to create plants that act as detection systems that are easy to understand, affordable, available to a mass public and can work quickly. The scientists will focus on genetically engineering plants to lose their color in response to a chemical, biological or viral compound introduced into the environment. According to researchers, there is a national need for a simple system that can rapidly report adverse environmental inputs.
"Since Sept. 11, 2001, national defense has taken on a different meaning. America has always been somewhat isolated from global conflict by the Atlantic and Pacific oceans; however, we now must consider that warfare in the form of biological and chemical weapons could be deployed at home by terrorists," said Reddy, who also is a professor of biology at Colorado State. "Our proposed work will use the strength of plant biotechnology to defend America from attacks based on weaponized forms of biological and chemical agents."
According to the researchers, plants, unlike some technologies being proposed to detect biological and chemical agents, are much more affordable and can last for years.
"People are accustomed to plants and not to chemical sensors," said Medford. "Plant sentinels would be unthreatening to the general public and could be deployed in shopping malls and office buildings where people would recognize an immediate loss of green color. In addition, the loss of green color could be rapidly quantified by authorities with portable hand-held equipment."
In vast geographic areas, the researchers said that detector systems could be introduced into trees and plants typical for landscapes, such as evergreens, and aquatic areas, such as algae, allowing satellites to monitor and perceive any change of color in response to detection of adverse agents.
"The plants would provide warnings so people could immediately vacate an affected area, and then experts could verify exactly what the agent is," said Reddy. "Unlike the Bio-Watch plan which would take 12 to 24 hours to detect and report pathogens, the plants would give nearly immediate warnings."
The Colorado State biologists would eventually like to create a separate type of plant and tree that would detect each type of threatening agent: biological, chemical and viral.
In nature, the color loss of plants and trees is a slow process; in the lab, the scientists are working to rapidly speed up that progression. To develop a plant system that will rapidly lose green color in response to harmful agents, the biologists are constructing a de-greening circuit by assembling genes that will simultaneously initiate chlorophyll breakdown while preventing new chlorophyll biosynthesis.
The de-greening circuit will be assembled in a plug-and-play manner, meaning that components of one circuit in one plant can be placed in other types of plants. Additionally, the de-greening circuit will be engineered to respond to specific biological and chemical weapons. The researchers are also building in a redundant system to eliminate false positives: if someone poured a soda in a plant, or if the plant detected another non-harmful agent, it would not lose its color.
During phase one of the DARPA research project, the scientists are not experimenting with any harmful agents, but are developing, through genetic engineering, the plant systems and the de-greening circuit. Once these systems are proven successful, phase two will incorporate advanced research in collaboration with university researchers in microbiology and horticulture, as well as researchers at the Centers for Disease Control.