Ultrafast laser spectroscopy has made the central contributions to the understanding of photo-machinery in nature such as photosynthesis and photosensory receptors, leading to the important applications in energy utilization for the former and optogenetics for the latter.Here,we present our recent studies of important biological systems, repair of UV-damaged DNA by photoenzyme photolyase to prevent the potential skin cancer and triggering of signal transduction by UV photoreceptor UVR8 to prevent UV damage.