Perhaps the most famous prop in Star Trek, characters use the fictional tricorder to instantly analyze and identify objects. Point and click, and the handheld device instantly performs environment scans, data recording and data analysis.
Working to distinguish plant populations on the top of Alaskan mountains, researchers with Chicago’s Field Museum thought it would be especially handy to have a tricorder—especially given how long it normally takes scientists to differentiate between plant species.
Typically, researchers must collect plant samples, store them, get permits to move them to the lab, then go through the many steps to actually sequence the plants’ genetic codes and compare them—a process that can take weeks or even months.
While the fictional tricorder with its instantaneous results would be perfect for this project, Dawson White and his team had to find another method that could reveal DNA differences quickly. In a new study published in New Phytologist, White demonstrates how and why spectroradiometers are the perfect alternative.
“In this new study, we’ve shown that you can use light instead of DNA to define plant populations, at a similar level of detail,” explains White, a postdoctoral researcher at the Field Museum. “This new method is a lot faster and cheaper than genetic testing, which could dramatically increase our efficiency at mapping and monitoring biodiversity.”
Spectroradiometers measure how much light reflects off a surface and what wavelengths that light contains. Agricultural scientists typically use spectroradiometers to analyze light bouncing back off of leaves to detect disease. But, White’s study reveals that the light bouncing off leaves varies from one population of plants to the next.
For their study, White and his colleagues from the Schoodic Institute and the University of Maine brought a spectroradiometer up to alpine habitats in Alaska where they could study a small evergreen shrub called Dryas. The researchers scanned the plants’ leaves and collected samples that they could analyze back in the lab.
The researchers found that, from one mountaintop to the next, the leaves of Dryas reflected back different amounts of light at different wavelengths. Even more surprising, once they sequenced the plants’ genomes, the team saw that these differences in reflectance corresponded precisely with plants’ genetic differences.
“Leaves have evolved to interact with light, and these machines are recording differences in the light after photons have entered the leaves and been absorbed or bounced around based on different chemistry and structure,” said White. “A spectroradiometer reads the visible and infrared light that bounces back off of the leaf, and that can give you a tremendous amount of information about the chemistry and structure of the leaf.”
This finding means researchers can use the light a plant reflects as a quick, reliable, in-field substitute for lengthy genetic testing when trying to determine if a population of plants is unique. It also holds positive implications for mapping and monitoring biodiversity and conservation. For scientists working to preserve threatened populations, being able to tell one genetic population of plants from another is critical.
The research team says they will continue to use this method for sampling, while keeping an eye on the technology while it continues to improve. In the future, they hope to be able to use unmanned aerial vehicles to detect plant genetic diversity with the same level of accuracy afforded to them today via portable spectroradiometers.
Photo: Dryas plants on an Alaskan mountaintop. Credit: Catherine Chan