The photo-protective role of vitamin D in the microalga .

An essential interaction between sunlight and eukaryotes involves vitamin D production through exposure to ultraviolet (UV) radiation. While extensively studied in vertebrates, the role of vitamin D in non-animal eukaryotes like microalgae remains unclear. Here, we investigate the potential involvement of vitamin D in the UV-triggered response of , a microalga inhabiting shallow ocean depths that are exposed to UV. Our results show that produces vitamin D and D in response to UV. We further demonstrate that responds to external administration of vitamin D at the transcriptional level, regulating protective mechanisms that are also responsive to UV. Our data reveal that vitamin D addition enhances algal photosynthetic performance while reducing harmful reactive oxygen species buildup. This study contributes to understanding the function of vitamin D in and its role in non-animal eukaryotes, as well as its potential importance in marine ecosystems.