Press release: Evolution of algal sunscreen
No. 84 - 15.06.2026
Research team at Göttingen University study how plants' algal relatives survive harsh sunlight
A new study sheds light on how the ancestors of modern land plants survived one of the most challenging aspects of life outside water: exposure to harmful ultraviolet (UV) radiation. By examining a microscopic alga closely related to the earliest land plants, researchers have uncovered a sophisticated and dynamic system for coping with sunburn – one that likely helped plants to colonize land over 500 million years ago. The results were published in Current Biology.
When plants first moved from water onto land, they faced a barrage of new stressors, including dehydration, temperature fluctuations, and intense sunlight. Among these, UV radiation posed a serious threat, capable of damaging DNA, proteins, and cellular structures. Understanding how early plants dealt with this challenge has long been a key question in evolutionary biology. To investigate, the research team studied Mesotaenium endlicherianum, a single-celled green alga belonging to the zygnematophytes – the closest known relatives of land plants. Because of this evolutionary position, these algae provide a unique window into the biological toolkit that may have enabled the first plants to survive on land.
Upon exposure to UV-B radiation in the lab, Mesotaenium cells reacted almost immediately. Within an hour, their photosynthetic efficiency dropped significantly, indicating stress. At the same time, the cells began to reorganize internally, forming specialized compartments called “vacuoles” and altering the positioning of their chloroplasts – structures responsible for photosynthesis. “These changes suggest the cells are actively protecting themselves, possibly by reducing light absorption and compartmentalizing harmful byproducts,” explains Cäcilia Kunz, first author and senior PhD researcher, Göttingen University. At the genetic level, the algae activated a wide range of stress-response genes. Many of these genes are also found in modern land plants, indicating a strongly conserved system that pre-dates the transition to land. This included UV-sensing proteins detecting harmful radiation, pathways that relay stress signals, DNA repair machinery for UV-induced damage, and regulators of photosynthesis that adjust energy production under stress. The study also identified activation of kinase signalling networks – molecular “switchboards” that coordinate cellular responses – as well as elements linked to hormone signalling pathways known from land plants.
Beyond genetic responses, Mesotaenium produced a wide array of chemical compounds in response to UV exposure. Many of these belong to a class called phenolics, which are known in land plants to act as UV sunscreens and antioxidants. “We also found a range of previously unknown chemical derivatives, suggesting the presence of untapped and unique metabolic pathways” says Professor Jan de Vries.
“This study provides a comprehensive model of how early plant relatives responded to UV radiation,” Kunz concludes. “Many of these mechanisms were likely already in place before plants moved onto land, forming the foundation for terrestrial life.” Understanding how early plants adapted to UV radiation not only answers fundamental questions about evolution but also has current implications. Insights into stress tolerance mechanisms could inform crop improvement, especially as plants face increasing environmental stressors.
This research was supported by the German Research Foundation (DFG), the European Research Council (ERC), and other international funding bodies.
Original publication: Kunz C et al “Chemodiverse cell system responses to UV in an algal sister of land plants”. Current Biology 2026, DOI: 10.1016/j.cub.2026.04.015
Contact:
Cäcilia F Kunz
University of Göttingen
Institute of Microbiology and Genetics
Department of Applied Bioinformatics
37077 Göttingen, Germany
Email: caeciliafelicitas.kunz@uni-goettingen.de
Professor Jan de Vries
University of Göttingen
Institute of Microbiology and Genetics
Department of Applied Bioinformatics
37077 Göttingen, Germany
Email: devries.jan@uni-goettingen.de
www.uni-goettingen.de/en/613776.html