The Anti-Icing Mechanism of Plants
By Jasmine Biju
March 4, 2023
UPDATED 12:00PM
[Photo Credit: Northwestern]
The magnificent ability of plants to live through frost phases has been intensively scrutinized by scientists. At the Zoological Institute of Christian-Albrechts-Universität zu Kiel (CAU), researchers utilized a cryo-scanning electron microscope in order to depict the microscopic imaging of the icing process that occurs on the surface of plants, specifically those native to Germany and Antarctica. The findings demonstrate that plants obtain special properties and structures that serve as a defense mechanism against freezing temperatures.
Airplanes avoid frosting by the usage of chemicals or a heated surface. Similarly, plants have their own structural advantages that allow them to prosper despite frigid environmental conditions. To further scrutinize the existence of such advantageous adaptations, researchers have concentrated on chemical processes. To do so, scientists meticulously studied the link between ice crystals and diverse native wild plant species. The conclusion deduced that fragile hair-like structures called trichomes and waxy surfaces are responsible for the regulation of ice development.
To conduct research, scientists utilized a cryo-scanning electron microscope to identify nano-scale ice crystals. The samples collected were not dried, but rather frozen, in order to retain their original structure. This was accomplished by exposing the leaves to liquid nitrogen at negative 196 degrees Celsius. Using the microscope, clear images of ice crystals could be depicted. When the plants were placed at room temperature, the ice crystals proceeded to melt. The repetition of this cycle emulated the natural melting process with the exposure of sunlight.
An intriguing finding within this research is the variety of defense mechanisms used among diverse plant species. In other words, different leaves have adapted different characteristics in order to deal with polar external conditions. For instance, plants that have adopted trichomes, such as daisies, are oftentimes hydrophilic - meaning that it has a strong affinity towards water. The formation of ice crystals on these plants begins at the leaf tips and rapidly melts, which leaves the leaf layer beneath unharmed.
On the other hand, various leaf surfaces obtain nanoscale wax projections, which are superhydrophobic. This has the opposite effect of trichomes, meaning water molecules are immediately repelled. The Lotus Effect encompasses this process in which the nanoscopic architecture of the leaf helps to decrease water adhesion to its surface. In the cases in which water droplets are not hindered, the underlying leaf layer also remains unharmed.
The German scientists further scrutinized the prevalence of this adaptation in other plants specifically native to subzero temperatures. Deschampsia Antarctica, one of two flowering plants native to Antarctica, obtains augmented protection in which two protective layers, superimposed - or stacked - on top of each other, exist. Researchers have theorized that this is due to natural selection in response to extreme weather conditions. Some plant species, though, showcase a higher susceptibility to ice crystal formation. For instance, Prunus Laurocerasus, also known as cherry laurel, obtains soft leaves in which ice crystals effortlessly form; however, scientists have deemed that its ability to survive harsh winter conditions can be attributed to the prevalence of an antifreeze defense mechanism in its structure.
Though the anti-freezing processes exemplified by different plant species are still being further investigated by scientists, the current findings derived from a multitude of studies have showcased the prevalence of specific and purposeful structures within the leaf. Over time, plants have gradually adopted new mechanisms embedded within their surface-level nanoscale architecture to protect from polar external conditions.
Refernces
University, Kiel. “Special microscope shows different anti-icing strategies of plant leaves.” Phys.org, 2022, https://phys.org/news/2023-01-special-microscope-anti-icing-strategies.html
Gorb, Stanislav. Gorb, Elena. “Anti-icing strategies of plant surfaces: the ice formation of leaves visualized by Cryo-SEM experiments.” Springer Link, 2022, https://link.springer.com/article/10.1007/s00114-022-01789-7
“How do plants protect themselves against icing?” Kiel University Christian-Albrechts-Universität zu Kiel, 2022,
https://www.uni-kiel.de/en/details/news/017-anti-icing