Scientists have discovered the key molecule involved in the glow of bioluminescent fungi (Sci. Adv. 2017, DOI: 10.1126/sciadv.1602847). Numerous plants and animals exhibit bioluminescence. The biochemical pathways involved in this glow phenomenon have been, for the most part, well characterized. But though scientists recently identified one of the components involved in fungal bioluminescence, the full mechanism has remained a mystery. Now, a large international team led by Ilia V. Yampolsky of the Russian Academy of Sciences has identified and characterized fungal oxyluciferin, the molecule in glowing mushrooms that emits photons of a characteristic energy (or color) as it relaxes from an excited state to the ground state. Bioluminescence generally arises from a combination of a species’ unique luciferin molecules with an enzyme known as luciferase, plus oxygen and light. The reactions produce species-specific oxyluciferin in its excited state, which exhibits a species-specific color. Yampolsky’s team isolated oxyluciferin from extracts of Neonothopanus gardneri, a Brazilian fluorescent mushroom, and N. nambi, which is found in the rain forests of southern Vietnam. The team also discovered that fungal luciferase is “promiscuous”—that is, able to combine with multiple types of luciferins. This biochemical flexibility could allow scientists to tweak luminescence color and intensity.