The evolutionary history of seed plants shows how leaves reflect light...

According to Dudu Meireles, plant reflection spectra or the light profile sheets that are reflected over different wavelengths record the change and diversification of seed plants as a result of evolution. The UMaine assistant professor of plant development and systematics and colleagues from the USA, Canada, Switzerland and England examined how the spectra have developed and diversified over the past 350 million years of plant development.

The researchers found that by measuring the spectrum of light reflected from a leaf, they could identify the plant, learn about its chemistry and development, and determine its place in the tree of life, Meireles says. Spectra can also be used to “provide groundbreaking assessments of leaf development and phylogenetic diversity of plants on a global scale,” the group wrote in their report for the study. Meireles hopes to be able to carry out these measurements remotely with unmanned aerial vehicles, aircraft or satellites at some point.

“We know little about how plant traits and chemistry evolved because collecting the data is difficult and slow, but spectra allow us to collect that data at unprecedented speed,” Meireles says.

New phytologist, an international journal for plant science, published the group’s findings in its October 2020 issue and promoted the study on the cover. The cover also features art by Adriana Cavalcanti from Orono, an intermedia MFA student. According to the magazine, the leaf art created from punch holes in autumn leaves is a reminder of “how light reflection spectra capture the chemical diversity of leaves and reveal the evolutionary history of plants”.

Cavalcanti says she created the artwork, titled Biomimicry, last fall by punching a variety of leaves and gluing the various circles onto scrap wood to form a multi-colored leaf. The way technology is intertwined with science and nature inspired the piece, she says, adding how nature observation has influenced various technological advances.

While working on his research on plant reflection spectra, Meireles encouraged Cavalcanti, who is also a botanist, to submit “Biomimicry” New phytologist, She says. The magazine, which accepts original artwork reflecting the main theme of each issue, selected its piece to portray Merieles’ findings.

“When I heard that my work was being selected for the cover, it was a big surprise. First, because I don’t usually see any artwork on the cover of scientific journals. Second, because it was not created that way. “Cavalcanti says. “For me it’s just one example of how open-minded we have to be towards our own art creations; how important it is to give people space to gain their own perception of art. ”

The research team conducted the study using a data set of more than 16,000 leaf-level reflectance spectra ranging from visible to infrared light from 544 seed plant species in the tropical and temperate latitudes of America and Europe. They measured leaf spectra with two full-spectrum field spectroradiometers, leaf clips, and artificial light sources.

While spectra highlight the phylogenetic history of seed plants, the location of the signal that displays this information in spectra can vary between plant lines, according to researchers. For example, they found that the signal that sets the evolutionary record for the Monocot line of plants is in the near infrared light reflected from their leaves, but the signal for the Gymnosperm line is in the short-wave infrared light that is reflected from the Scroll is reflected. To monitor plant diversity, Meireles says scientists need to measure the full spectrum of light reflected from leaves, rather than a handful of ribbons.

The team created a model that can be used to simulate how different evolutionary dynamics, such as convergent adaptation to the shadow, affect the spectra. Their scaffolding also showed that evolution limits the variation in spectra in seed plants to varying degrees, particularly for the visible range associated with pigments such as chlorophyll and carotenoids.

Meireles and colleagues hope that the increasing availability of high-resolution spectral data not only for leaves but also at the canopy and landscape level will help improve scientists’ monitoring of plant biodiversity.

“The function of the ecosystem and thus also the well-being of humans depend on biological diversity. We need to monitor diversity in order to understand, manage and preserve it. Reflectance spectra are one of the best tools to get this job done efficiently. “Meireles says.