A farmer scans his crop with a hand-held device that measures the plants’ chemical content or detects a particular protein marker.
Sensors glow and an infection is confirmed. Calls are made. More measurements are taken. Producers head to their fields, and state and federal agents fly overhead with devices that call to mind the Star Trek tricorder. Within a few days the extent to which an entire region’s crop is threatened by a pathogen is assessed and mitigation efforts are in place.
It may sound farfetched, but research in the UT Institute of Agriculture Department of Plant Sciences could bring this futuristic scenario closer to actual practice than to a script destined for the Syfy channel.
Dr. Neal Stewart, a professor of plant science who also holds the Racheff Chair of Excellence in Plant Molecular Genetics, is the lead character at UT, and his laboratory is filled with graduate students, postdocs, and other researchers in supporting roles, eager to bring their ideas to fruition.
The concept is driven by a need to protect modern-day monoculture crops from a single source of infection. “We’re working to prevent the massive loss of an important food or fiber crop from a naturally occurring disease or from a pathogen or a chemical that could be intentionally released,” says Stewart.
One way is to produce “sentinel plants.”
Scientists in Stewart’s lab are genetically modifying plants to emit a unique spectral signature during the early stages of infection; that is they would “change color” before a farmer would normally detect other signs of infection. “The sentinels could be planted on a grid along with the other crops to monitor plant disease in real time,” says Stewart. “Their genetic makeup could allow for the early detection of a plant disease before it is able to damage an entire crop.” Special photonic sensors—the “tricorder” of sorts—would be needed to detect the subtle changes in color in the sentinel plants. Stewart’s project “Phytosensors for Crop Security and Precision Agriculture” was recently awarded a $1-million federal grant for the vision that combines biotechnology and photonics.
For many planners and government agencies, the events of 9/11 helped focus attention on the vulnerability of today’s widespread monoculture, or -single-crop, agricultural production methods. A single pathogen introduced by Mother Nature or by those with intent to harm could devastate an entire region’s crop. “In the case of either a natural infection or one introduced by agri-terrorists, an early warning system would be invaluable for protecting our food supply or a region’s economy. If farmers know about an outbreak of a disease before symptoms show, then crops can be treated and rescued with minimal economic losses,” Stewart says.
The science involved is anything but simple. Stewart’s team—Mitra Mazarei, Mary Rudis, Murali Rao, Laura Abercrombie, Wusheng Liu, and Yanhui Peng—has been working to synthetically fuse fluorescent reporter genes with plant proteins produced in response to pathogens. When the team’s modified plants encounter pathogens, they produce fluorescent proteins whose glow, though not visible to human eyes, can be detected by instruments. The lab has been testing the technology in tobacco and Arabidopsis, a small plant from the mustard family, because the genetics of these plants is well documented. But once the technology is perfected, the plan is to transfer the concept to crops like corn, cotton, and soybeans.
Another approach the team is considering is producing plants that respond to the presence of particular pathogens by altering their physical characteristics.
Stewart says, however, that it’s important to apply the technology to targets other than pathogens. For example, the team has been working on genetic markers that can detect arsenic, TNT, or other compounds that can leak from landmines. Sentinel plants in old minefields could be used to detect long-hidden threats. The United Nations’ Electronic Mine Information Network estimates that between 15,000 and 20,000 people are killed or injured by these weapons every year in at least 78 countries around the world, including Afghanistan and Sudan.
Stewart sees a number of other future applications of the technology for biosecurity. For example, Hong S. Moon, another Ph.D. student in Stewart’s lab, is extending the technology to monitor the flow of genes via pollen grains from genetically engineered cultivated plants to their wild relatives. Governmental regulators of crop biotechnology worldwide are concerned about the effect the science might have on the natural world. Moon is first author on a paper on the topic that appeared in the January 2010 issue of Trends in Biotechnology.
“I expect the future will also include precision agriculture phytosensors for the monitoring of field fertility and water stress, which can aid our environmental stewardship of natural resources and economic farm management,” Stewart predicts. “The technology could fundamentally change the way crop health is monitored and protected.” — Patricia McDaniels