Ultraviolet-B(UV-B) radiation is a key environmental signal that is specifically perceived by plants to promote UV acclimation and survival in sunlight.In contrast to phytochrome-,cryptochrome- and phototropin-sensing systems,with considerable knowledge accumulated,the UV-B photoreceptor UV Resistance locus 8 (UVR8) was only recently described at the molecular level.UV-B perception was thought to induce dissociation of the UVR8 homodimer,allowing its subsequent interaction with Constitutively Photomorphogenic 1(COP1) and activation of UV-B responsive genes.Here,we review the recent studies of the UVR8 photoreceptor in the context of UVR8 discovery,UVR8 structure,UV-B perception mechanism,UVR8 redimerization and the commonalities and differences between UV-B and visible light signaling.