Different compounds in flower petals form a “bulls-eye” for pollinating insects, according to a Clemson University professor whose study provides insight on chemical changes in flowers that allow them adjust to environmental changes, including climate change, that may jeopardize their existence.
Matthew H. Koski, an assistant professor of biological sciences in the Clemson College of Science, led a research team that studied the bright, yellow flowers of Argentina anserina, a member of the rose family commonly known as silverweed, to learn how pigments in the petals visible only in the ultraviolet spectrum play an important role in the plant’s plasticity, or its ability to respond quickly to a changing environment. Lindsay M. Finnell, Elizabeth Leonard, and Nishanth Tharayil of Clemson University were also members of the team.
The results were highlighted on the cover of the journal Evolution’s March issue.
The researchers researched silverweed at various altitudes in southern Colorado to better understand the functions of the numerous UV-absorbing compounds in the plants’ petals and how these chemicals act to help in pollination and, hence, reproduction.
Although humans cannot see the UV patterns on the flower’s petals, many of its pollinators can, according to Koski.
“I’ve always been fascinated with how [flower color variation] arises, how it evolves, and what factors drive the evolution of color variation,” Koski explained, “so I became interested in thinking about how we perceive color versus how organisms that interact with flowers more frequently perceive color.”
“Insects, for example, pollinators, see in the UV spectrum,” he explained. “Flowers that reflect or absorb UV wavelengths, for example, offer pollinators the sense of distinct hues that humans cannot perceive. I’ve been curious in what these UV signals could be doing functionally in terms of pollination. When I consider the attribute of interest in UV absorption, I think of biology. It’s a biological characteristic that causes differing perceptions of UV absorption and reflectance.”
According to Koski, UV-absorbing compounds are concentrated at the base of the flower’s petals, while UV-reflecting chemicals are concentrated at the tips of the petals. According to him, this results in an overall “bulls-eye” effect that leads insects in their quest for pollen.
The researchers hoped to learn more about how plants adapt to flourish in varied settings, in this instance, a 1,000-meter variation in height. They discovered that flowers at various elevations adjust to their surroundings by creating varying levels of UV-blocking or UV-absorbing compounds.
“There are usually more UV-absorbing chemicals or a bigger spatial region of UV absorption on the petals at higher altitudes, compared to low-elevation populations,” Koski said.
This, according to the researchers, indicates the plant’s plasticity, which Koski characterized as how various features emerge in the same species under different environmental settings. This is an important step in understanding how organisms adapt to change.
“What’s interesting about plasticity is that when we think about climate change and global change, plasticity is one way by which natural populations can adjust fairly quickly to changing climates and remain in those climates,” he said. “The process of evolution, in which changes in the genetic code occur through time, is assumed to move more slowly than just reacting plastically to environmental change.”
One concern presented by the findings, according to Koski, is whether plastic reactions to environmental conditions are adaptive. Do they provide any benefit to an organism, or are they alterations in how a characteristic develops as a result of the environment that have no influence on plant fitness?
“One thing our research discovered is that the plastic shift in UV pigmentation helped the plant, particularly those at high altitudes, since increases in ultraviolet absorption on the petals resulted in greater pollen viability,” he said.
According to Koski, the findings will help scientists better understand how organisms adapt to environmental changes and even forecast whether or not particular creatures would be able to endure fast environmental change, such as that caused by global climate change. He believes the discovery might be useful in agriculture since several of the UV-sensitive pigments found in silverweed are also found in commercial crops such as mustard and sunflowers.
“It’s intriguing to think about how, if abiotic variables like UV or temperature are affecting the expression of these features, how that would effect how pollinators perceive the blooms, and how that will affect things like yield and seed generation in crops, for example,” Koski said.
The team’s findings might be useful for home gardeners attempting to attract certain species of pollinators to their plants.
“I believe one thing people think about is growing a variety of flowers with various colors and morphologies to attract many different sorts of pollinators, like a pollinator-friendly garden,” said Koski. “One issue to consider is that we frequently don’t know all of the intricacies of what colors pollinators see and how that may change with the seasons. Although things may seem to be quite similar to us, they may be highly varied to pollinators and may attract a different set of pollinators than we anticipate.”
