The Role of Vitamin D inEmiliania huxleyi: A Microalgal Perspective on UV Exposure

An essential interaction between sunlight and eukaryotes involves the production of vitamin D through exposure to ultraviolet (UV) radiation. While extensively studied in vertebrates, the role of vitamin D in non-animal eukaryotes like microalgae remains unclear. To investigate the potential involvement of vitamin D in the response of microalgae to UV, we focus on Emiliania huxleyi , a microalga found in shallow ocean depths that are exposed to UV radiation. Our results show that E. huxleyi algae produce vitamin D 2 and D 3 in response to UV irradiation. We further demonstrate that E. huxleyi algae respond to external administration of vitamin D at the transcriptional level, regulating the expression of protective mechanisms that are also regulated in response to UV. Our data reveal that addition of vitamin D enhances the algal photosynthetic performance while reducing harmful reactive oxygen species buildup. This study contributes to understanding the function of vitamin D in E. huxleyi and sheds light on its role in non-animal eukaryotes, as well as its potential importance in marine ecosystems.