The strange mushroom glows in the dark

Author: Dennis E. Desjardin, Department of Biology, San Francisco State University

At the end of the afternoon on a new moon day, we arranged for things to go on the road including hiking boots, pants, long sleeves, knife belts and GPS attached, head mounted hats, backpacks. It was filled with water, food and horse bottles. Our expedition has 7 members. We drove 30 minutes on dirt roads leading into the forest. When the place came, the local people guided us to take us further 6 kilometers to the center of the forest.

We are the mushroom research team on the way to look for bioluminescent fungi. They can glow 24 hours a day but can observe the phenomenon best at night.

Photo of Mycena lucentipes has just been named in Sao Paolo, Brazil.(Photo: Cassius V. Stevani, Chemistry Institute, University of Sao Paulo)

Our study area is a special place, this is one of the few remaining places of the Atlantic Forest habitat in southern Brazil. At night the forest is full of buzzing, clattering sounds of thousands of insects, crawling spiders, scurrying small mammals, bull snakes crawling or mottling quietly but deadly. This is an extremely interesting place to enjoy and admire even when we no longer look at it.

The stars are at the feet

Our group went to explore at night so we clung to each other. But the fear of leopards prefers individual prey to not be as great as the fear of being lost.

Dark photos of Mycena lucentipes.(Photo: Cassius V. Stevani, Chemistry Institute, University of Sao Paulo)

By the time it stopped, it was so dark that I could not see my hand even in front of me. After turning on the lights on the hat to illuminate the way to the destination, we turned it off and fell groping in the dark looking for tiny yellowish green lights. We hope it is luminescent mushrooms.

We looked down on the ground looking as if looking at the starry sky. We see a lot of things that look like fireflies, only they don't blink and don't move. They turned out to be tiny mushroom caps belonging to a species we named Mycena asterina (meaning little stars).

Going deeper into the forest we encountered a moss-covered tree glowing with the mushroom Gerronema viridilucens - a new species. Next to a log is the glowing Mycena fera. That night we all discovered 8 different luminescent mushrooms, more than anywhere in the world.

How and why?

There are about 85,000 species of the Mushroom Kingdom, with about 9,000 species forming the organism of the fungus family called Agaricales (Basidiomycota, Agaricomycetidae). The focus of NSF-funded research is to document the diversity of Agaricales in untreated tropical forests and to study the evolutionary relationships among species.

An image of an unnamed fungus is often called Mycena luxaeterna.(Photo: Cassius V. Stevani, Chemistry Institute, University of Sao Paulo)

Part of our research is about bioluminescent fungal species. Interestingly, only about 65 species in the Kingdom are detected with luminescence. The Cassius Stevani Institute of Chemistry, University of Sao Paulo also contributed to the study.

The questions that we are trying to answer include: Why are there so few luminescent fungi? What is the mechanism of luminescence? When and how many times does luminescence evolve? Why are they glowing?

Here's what we've learned so far: All 65 species of fungi that have luminescence are capillary fungi, which produce white gametes with thin walls to spread. They are both capable of digesting both cellulose and lignin in plant crumbs. The tropics have the largest diversity, although very few fungi live in temperate regions. They glowed continuously, emitting yellowish-green light with frequencies of 520 - 530 nanometers. Not all parts of the mushroom are glowing, in some species only the cap or leaves in the hat glow. While some other species have this ability only in the mushroom body. Some species are not glowing but there are fibers called mycelium that the fungus has grown so bright.

Dark photo of Mycena luxaeterna mushroom.(Photo: Cassius V. Stevani, Chemistry Institute, University of Sao Paulo)

Cassius Stevani was a project chemist, and he collaborated with us to study the bioluminescence mechanism of fungi. It is the luciferin-luciferase intermediate reaction that produces light when water and oxygen are present. This reaction is both the same and the other reacts in luminescent bacteria, dinoflagellates or animals. Currently, the exact compound used as substrate (luciferin) and enzyme (luciferase) has not been discovered, but we are approaching very close to them.

Some answers are few

In my lab, my colleague Brian Perry is establishing the DNA sequence of 65 luminescent fungal species to understand the evolution of luminescent phenomena. We know that there are 4 different mushrooms that can glow. Common North American fungi such as Truffles (Omphalotus spp.) And Honey Mushrooms ((Armillaria spp.) Belong to two different mushrooms.

They are the most diverse of the four fungal families, mycenoid (Mycena and relatives), with 46 out of 65 species discovered, accounting for 75%. All 8 fungal species we discovered in one location in the Brazilian territory belong to this family. The most interesting thing is: when we looked at the relationship of 500 species of mycenoid mushrooms, we found that 46 species of luminescent mushrooms belong to 16 different families.

The photo was taken from the Brazilian research group in March 2007. The leader of the group was Dr. Cassius V. Stevani and Dr. Dennis E. Desjardin in the middle of the top, from the left.(Photo: Dennis E. Desjardin, Department of Biology, San Francisco State University)

Does this mean that the ability to glow has evolved 16 times different? Not really. Our data suggest that the original light source of fungi originates from the losses that light-emitting capacity brings.

Why are they glowing? The data suggest that some fungal species glow to attract night-active animals to spread gametes. This is extremely suitable for dense forests of canopy trees where the wind cannot be judged. Some other species glow to attract enemies that come to eat mushrooms by insects, this is a plan to make friends with the enemies of mushrooms. Some species are glowing for reasons that we cannot explain yet. And we're trying to find that out.