As the climate changes, a Clemson University biologist is leading an international effort to understand how flowers keep from overheating.
Matthew Koski, an associate professor in the Department of Biological Sciences, received a $1.2 million grant from the Human Frontier Science Program, an international organization that funds collaborative, high-risk scientific research spanning multiple countries and disciplines.
The project connects researchers from Clemson, the University of Cambridge in the United Kingdom and the National Institute for Materials Science in Japan to investigate how flowers regulate temperature under climate stress. The study combines plant biology, developmental genetics and materials science.
“Under warming climates, plants can’t get up and move to suitable micro habitats,” Koski said. “They’re just out there experiencing pretty extreme temperatures.”
The three-year project focuses on one of the most vulnerable stages in a plant’s life cycle: the flowering stage, when excessive heat can damage pollen and ovules, reduce successful reproduction and reduce seed production.
Scientists have long studied how flowers warm themselves in cold climates through traits such as petal cupping to retain heat and heliotropism, or the daily movement of plant parts to follow the sun’s path across the sky.
Staying cool
Far less is known about whether flowers possess traits that help them stay cool.
“There are a lot of ways that we know plants can warm up their flowers,” Koski said. “But we’re particularly interested in the ways that plants can cool their flowers because that should be more important in the conditions we’re experiencing now of rapid climate warming.”
The researchers will investigate microscopic structures on flower petals known as epidermal cells. These cells vary in shape and texture and may influence how sunlight reflects off petals. Some flowers have flatter cells that may reflect more solar radiation, while others have conical or ridged cells that absorb more heat, he said.
“All of these microscale differences in petal cell shape affect how light is going to bounce off that petal,” Koski said.
Using genetically modified hibiscus plants developed in Cambridge, the team will compare flowers that differ only in petal cell structure. That allows researchers to isolate whether specific cell shapes alter flower temperature.
Satoshi Ishii’s lab in Japan will contribute thermodynamic modeling and advanced materials engineering. Researchers will also fabricate artificial flowers to test how petal textures influence heat independently of other biological traits.
The project will expand beyond hibiscus to examine 60 flowering plant species across the United States, the United Kingdom and Japan. Researchers hope to determine whether plants growing in hotter climates have evolved traits that help flowers remain cooler.
Agricultural implications
Koski said the research could have implications for agriculture as global temperatures rise. In addition, the research could benefit pollinators. Koski said pollinators can overheat while foraging inside flowers. Some small pollinators must take “cooling flights” because they can get dangerously hot while feeding inside flowers exposed to strong sunlight.
“There might be some other benefits to identifying these cooling traits because they might be in flowers that are more attractive to pollinators under warming conditions and might better support pollinator health,” he said.
Another focus of the project is identifying cooling mechanisms that do not depend on water. Plants often cool themselves through evaporation, similar to sweating, but drought conditions may limit that ability.
In addition, Koski said the research has the potential to contribute to bioinspired cooling designs for buildings and any product exposed to high levels of radiation.
