Why do fungi glow in the dark?

bioluminescent_fungi

The paper:

Oliveira, A. G., Stevani, C. V., Waldenmaier, H. E., Viviani, V., Emerson, J. M., Loros, J. J., & Dunlap, J. C. (2015). Circadian control sheds light on fungal bioluminescence. Current Biology, 25(7), 964-968.

Simple summary:

Why do fungi glow in the dark? Their super cool bioluminescence is thought to attract insects to help spread their spores in the forest understory. This is important adaptation in forest ecosystems because there is less wind to carry their spores far and wide.

The article abstract:

From the article:

Highlights

  • Bioluminescence in N. gardneri, a basidiomycete, is regulated by the circadian clock
  • Luciferin, reductase, and luciferase, which together make light, all peak at night
  • Prosthetic LED-illuminated acrylic mushrooms can be used to study insect behavior
  • Insects that can disperse fungal spores are attracted to light at night

Summary.

Bioluminescence, the creation and emission of light by organisms, affords insight into the lives of organisms doing it. Luminous living things are widespread and access diverse mechanisms to generate and control luminescence [ 1–5 ]. Among the least studied bioluminescent organisms are phylogenetically rare fungi—only 71 species, all within the ∼9,000 fungi of the temperate and tropical Agaricales order—are reported from among ∼100,000 described fungal species [ 6, 7 ]. All require oxygen [ 8 ] and energy (NADH or NADPH) for bioluminescence and are reported to emit green light (λmax 530 nm) continuously, implying a metabolic function for bioluminescence, perhaps as a byproduct of oxidative metabolism in lignin degradation. Here, however, we report that bioluminescence from the mycelium of Neonothopanus gardneri is controlled by a temperature-compensated circadian clock, the result of cycles in content/activity of the luciferase, reductase, and luciferin that comprise the luminescent system. Because regulation implies an adaptive function for bioluminescence, a controversial question for more than two millennia [ 8–15 ], we examined interactions between luminescent fungi and insects [ 16 ]. Prosthetic acrylic resin “mushrooms,” internally illuminated by a green LED emitting light similar to the bioluminescence, attract staphilinid rove beetles (coleopterans), as well as hemipterans (true bugs), dipterans (flies), and hymenopterans (wasps and ants), at numbers far greater than dark control traps. Thus, circadian control may optimize energy use for when bioluminescence is most visible, attracting insects that can in turn help in spore dispersal, thereby benefitting fungi growing under the forest canopy, where wind flow is greatly reduced.