A team led by plant biologists at the universities of Freiburg and Göttingen in Germany showed for the first time that algae had a mechanism to protect them from the cold that was previously known only in flowering plants. Professor Ralph Riske at the Center of Excellence for Integrative Biological Signal Studies (CIBSS) at the University of Freiburg and Professor Evo Feusner at the Center for Molecular Biological Sciences (GZMB) at the University of Göttingen have shown that this mechanism is evolutionarily independent of origin – algae and flowering plants use a similar mechanism that relies on distant related genes. Moreover, it protects the organisms from pathogens as well as the cold. The moss Physcomitrella and the flowering plant Arabidopsis served as model organisms. The team published its study in the journal Nature plants.
More than 500 million years ago, plants began to leave water and colonize the earth. Algae and flowering plants evolutionarily diverged from a common ancestor plant. However, both of them had to find ways to protect themselves from the freezing temperatures on Earth. For example, it is essential that all plants maintain the fluidity of their cell membranes. Only liquid membranes allow transport across the septum that surrounds the plant cell as a protective covering. When the temperature drops, the membrane stiffens and becomes less permeable, which impairs cell functions. Plants can counter this because their cell membranes contain lipids that contain fatty acids. The more unsaturated fatty acids these fats contain, the lower the temperature at which the membrane solidifies.
The research team from Freiburg and Göttingen identified a novel protein that plays a key role in regulating fluidity in algae. It affects the degree of saturation of fatty acids in a group of membrane fats known as sphingolipids. When the researchers deleted the gene responsible for making this protein, they found that the plants were more sensitive to cold. At the same time, they were more susceptible to fungal infection – filamentous organisms associated with algae that include plant pathogens such as downy mildew and potato blight.
“Sphingolipids are important building blocks for cell recognition and signal transduction in humans, animals, and plants. We have discovered a previously unknown regulator of these sphingolipids in algae and have shown that it also works in a flowering plant. This opens up entirely new possibilities in synthetic biology,” Riske explains.
“Our work shows that algae and flowering plants have followed different pathways during evolution to adjust membrane fluidity in cold conditions in a similar way. This is a great example of convergence in plant evolution at the molecular level,” Vosner adds.
How the algae acquired this specific gene is unclear. The team also found it in genome data for fungi, flagellates, diatoms and a small group of single-celled algae that hasn’t been studied much yet.
Hannu Christophe Riesman, Cornelia Herforth, Kristen Wusner, Ellen Hornung, Anna K. Ostendorf, Jasmin Joman, Jennifer Mettag, Nico van Gisel, Jan de Vries, Gotta Ludwig Muller, Jennifer Markham, Ralph Riske, Evo Fossner (2021): Convergence from Sphingolipid desaturation over more than 500 million years of plant evolution. at: Nature plants. DOI: 10.1038 / s41477-020-00844-3
Prof. Dr. Ralph Rusky
College of Biology
University of Freiburg
Phone: +49 761 203 6969[email protected]
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