According to a study co-led by Dr Cassius Stevani of the University of São Paulo and Prof Jay Dunlap of the Geisel School of Medicine at Dartmouth, the green light emitted from bioluminescent fungi attracts the attention of insects, including beetles, flies, wasps, and ants, which are apparently good for the fungi because the insects spread their spores. The study also shows that their bioluminescence is controlled by a temperature-compensated circadian clock.
Neonothopanus gardneri. Image credit: Marina Capelari et al, doi: 10.3852/11-097.
Bioluminescence is simply the ability of organisms to produce light on their own. Jellyfish and fireflies might be the most familiar bioluminescent creatures, but organisms from bacteria to fungi to insects and fish make their own glow through a variety of chemical processes.
Glowing fungi have captured the imagination of cultures around the world. They have been well-known for centuries, from the bright orange and poisonous Jack-o-Lantern Mushroom (Omphalotus spp.) to the phenomenon known as ‘foxfire,’ where the nutrient-sipping threads of the Honey Mushroom (Armillaria spp.) give off a faint but eerie glow in rotten logs.
Only 71 of more than 100,000 recognized species of fungi produce light in a biochemical process that requires oxygen and energy.
Biologists had believed in most cases that fungi produce light around the clock, suggesting that perhaps it was a simple, if expensive, metabolic byproduct.
The new study, published online March 19 in the journal Current Biology, suggests that just isn’t so, at least not in the case of Neonothopanus gardneri, one of the biggest and brightest of glowing fungi.
Prof Dunlap, Dr Stevani and their colleagues found that the Neonothopanus gardneri’s glow is under the control of a temperature-compensated circadian clock. They suggest that this level of control probably helps the fungi save energy by turning on the light only when it’s easy to see.
To find out what that green glow might do for the fungi, the team made sticky, fake fungi out of acrylic resin and lit some from the inside with green LED lights.
When those pretend fungi were placed in the forest where the real Neonothopanus gardneri is found, the ones that were lit led many more staphilinid rove beetles, as well as flies, wasps, ants, and ‘true bugs,’ to get stuck than did sticky dark fungi.
The scientists said they are interested in identifying the genes responsible for the bioluminescence in fungi and exploring their interaction with the circadian clock that controls them. They are also using infrared cameras to watch the interaction between Neonothopanus gardneri and arthropods, especially larger ones, more closely.
“The findings are not only cool, they are also important in understanding how mushrooms are dispersed in the environment,” the scientists said.
“That’s key because fungi such as Neonothopanus gardneri play an important role in the forest ecosystem.”
_____
Anderson G. Oliveira et al. Circadian Control Sheds Light on Fungal Bioluminescence. Current Biology, published online March 19, 2015; doi: 10.1016/j.cub.2015.02.021
