A ray gun-like device helps scientists see plants in a different light

By Ashley Strickland, CNN

Scientists are aiming little ray gun-like devices, called leaf clips, at plants in an attempt to better understand biodiversity as environments respond to the climate crisis.

Not unlike the tricorder used to perform environment scans in “Star Trek,” the nifty gadget is a type of spectroradiometer that helps record how plant leaves reflect light differently — which actually reveals how genetically diverse one plant population is from another.

In a new study, a team of scientists used the leaf clip to record light reflected off plant leaves of two species of an evergreen shrub on different Alaskan mountains. The two plants were Dryas alaskensis and Dryas ajanensis. The populations of plants that the team analyzed on neighboring mountains were genetically different. This means that even though they are only separated by a few miles, the populations are genetically isolated because they aren’t sharing pollen.

Understanding the genetic diversity of these plants, as well as their need for conservation, fits into the broader goal of protecting Earth’s natural biodiversity.

The study published Tuesday in the journal New Phytologist.

“While trained biologists can usually walk into the field and identify species with their eyes, it takes expensive genetic analyses to reveal the populations — groups of individuals of the same species within a gene pool — that are so important for conservation and evolutionary research,” said co-lead study author Dawson White, a postdoctoral researcher at Chicago’s Field Museum, in a statement.

“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. This new method is a lot faster and cheaper than genetic testing, which could dramatically increase our efficiency at mapping and monitoring biodiversity.”

When botanists study plants to better understand their chemistry or genetics, it means collecting and storing plant samples, and taking careful measurements using microscopes, chemical testing or gene sequencing — all of which can be costly and time consuming, said Lance Stasinski, study co-lead author and graduate student researcher at the University of Maine.

A valuable field tool

But the leaf clip “opens up many doors into studying plants” that can limit the time and money typically spent on these analyses, Stasinski said. And it’s a much more immediate result that can be gathered in the field.

“There is a lot of information that can be gathered from light reflected from leaves,” he said. “A short list of features includes: leaf pigments, leaf structure, water content, nitrogen and carbon content, and more. You can then use that light to differentiate species considering individual plants within the same group share the aforementioned features.”

“For example, we see the concentration of pigments that underlie photosynthesis, the concentration of defense compounds used to deter pests, how much water a leaf holds, the amount of carbon that a plant invests per leaf, among many other things,” added Joseé “Dudu” Meireles, study coauthor and assistant professor at the University of Maine.

Light readings taken at leaf level can also be compared with measurements collected from aerial drones, aircraft or satellites as well.

“The future holds many space-based versions of these types of sensors so I am excited to use these larger foot-print datasets in combination with fine, ground-based or airborne spectrometer data,” said Peter R. Nelson, forest ecology director at Schoodic Institute at Acadia National Park and associate faculty at the University of Maine, School of Forest Resources.

Genetic diversity for species health

Understanding the genetics of plant populations can help scientists preserve those that are threatened or endangered.

“Genetic diversity is really the driver of evolution and a mechanism that ensures the long-term survival of a species in a changing world,” Stasinski said. “The more genetic populations we conserve, the more likely that species will contain genes within its gene pool that will allow it to adapt to change. The genetic differences between two populations could hint at how each are responding to local climate change.”

If a plant population needs to adapt to increasing temperatures, the genes may adapt over generations and correspond to attributes that help the plant dissipate that heat.

“Now that we understand that each one of these mountaintops is genetically unique, that means that there are implications for conservation,” said Rick Ree, a study coauthor and curator at the Field Museum, in a statement. “If we want to try and maintain genetic diversity through time, especially given the shrinking habitats of alpine ecosystems due to climate change, then the implication (is) that we should be sampling from every mountaintop.

Biodiversity is an essential part of maintaining clean water, fresh air and healthy soils, Stasinski explained. A diversity of species across ecological niches help maintain healthy ecosystems, he said.

“Humans are not disconnected from ecosystem health, so it is crucial that we study and maintain biodiversity to, at the very least, ensure the survival of our species, but optimally to preserve the beauty and diversity of life that we are fortunate enough to cohabitate with,” Stasinski said. “This concept of conserving biodiversity is especially crucial in the face of climate change considering that biodiversity is already responding to the changing world.”

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