TROPICAL FUNGI 3-30-10

The key to forest health.

HOW DOES A FUNGUS GROW? The living body of the fungus is a grayish,

stringy mass called a mycelium (= the green plant of a rose bush).

The fruiting body of the fungus is the mushroom (= the rose of a rose bush).

The mushroom produces spores that result in new fungi.

HOW DOES A FUNGUS OBTAIN NUTRITION? Fungi can be saprophytic, meaning that they

feed on non-living materials. Their mycelia use chemicals to dissolve and absorb nutrients.

Fungi can be parasitic, meaning that they feed on living materials. – On plants (smuts, rusts)– On animals (Histoplasma in human lungs)

Fungi can also be mutualistic, living with other organisms.– Lichens

The mycelia of many species of fungi unite with the roots of forest trees. These mutualistic symbiotic mycorrhizal associations provide the fungus with photosynthesized products and the trees with chemically obtained nutrients. The mycelia grow so fast that they capture most of the nutrients.

A nice image of the mycorrhizal association.

The mycelium breaks down organic matter and absorbs phosphorus and potassium.

Several mycelia.

Fairy Ring (so called because people believe that fairies come out and dance in the circle) – Since the mushrooms (fruiting bodies) use a lot of nutrients, they tend to pop up around the periphery of the growing mycelium. The mycelium is consuming nutrients where it exists.

Bracket Fungi, Belize. Remember, the brackets are the reproductive portion, and the body of the fungus is the mycelium that is in the dead limb.

Shelf Fungi – Cockscomb.

Bracket fungus in Trinidad.

Basidiomycete in Belize 2006

Interesting fungi growing among cahune palm seeds in Caracol.

Puffballs are common. When touched, they send out a cloud of grayish spores.

Cute little gray mushroom growing on poo. El Cedral, Venezuela.

Magic mushrooms - aka ‘shrooms – (Psilocybe sp.) growing on cow poo at Crooked Tree, Belize. Beware the effects of psilocybin

Cute! Tambopata, Perú.

Tambopata, Perú.

There is a whole group of mushrooms called stinkhorns due to their putrid smell. They emit putrescine (a polyamine precursor of spermidine, first found in decaying meat but now known to occur in almost all tissues and in some bacterial cultures; a crystalline, slightly poisonous, colorless, foul-smelling ptomaine [a product of bacterial or protein metabolism] produced by the decarboxylation of ornithine, especially in decaying animal tissue) and cadaverine (a foul-smelling nitrogenous base, pentamethylenediamine, produced by decarboxylation of lysine). It is produced in decaying protein material by the action of bacteria, particularly species of Vibrio.

WHAT YOU NEED TO KNOW: Stinkhorns produce putrescine and cadaverine, and both have a horrible odor associated with decaying flesh. Yuk!

What is the selective advantage of emitting putrescine and cadaverine?

To attract flies, which are the agent for the distribution of their spores.

Lacey Stinkhorn, Dictophora, Hato El Cedral, Apure, Venezuela. Its putrid smell attracts flies that spread the spores, as do all stinkhorns.

Bridal Veil Stinkhorn, Dictyophora indusiata, Cockscomb. The vail is technically called an indusium (outgrowth).

Stinkhorn, Belize.

Yet another stickhorn is Clathrus crispus. This one appeared overnight at Chaa Creek during a heavy rain storm in August, 2007. These mushrooms deteriorate quickly, lasting less than one day. Note the flies.

One weird student!

Mushrooms, Cockscomb, Belize.

This fungus has dissolved all of the leaf but the ribs and edges (found in Cockscomb).

Cordyceps – ONE OF THE UNIQUE FUNGI OF THE TROPICS. Cordyceps is a tropical fungus that grows in

the ground. An invertebrate (tarantula, insect, etc.)

brushes against the mushroom and spores stick to its exoskeleton.

Spores begin to grow, entering openings in the exoskeleton.

As the mycelium grows, the carrier can’t resist the urge to climb up vegetation.

At some point, the fungus kills the carrier, which turns white with fungal growth.

MORE ON Cordyceps . . .

The fungus produces spores. The dead carrier ruptures. The spores blow away in the breeze. This whole system seems to have

evolved to help the dispersal of the Cordyceps spores.

http://www.youtube.com/watch?v=Guk-x0BTDTM

LICHENS ARE . . .

Lichens are a mutualistic symbiotic association of a fungus and algae or cyanobacteria.

The fungus gets food from the photosynthesizing algal cells.

The algae get moisture and a place to live from the fungus.

Remember: “An alga took a likin’ to a fungus.”

TYPES OF LICHENS Foliose: leaf-like lichen (curly lobes and

margins)

Types of Lichens (cont.)

Crustose: crust-like lichen (adhere tightly to the surface; rather coarse to the touch)

Types of Lichens (cont.) Fruticose: shrub-like lichen; In fact, they

belong to the genus Usnea (the scientific name of Spanish moss is Tillandsia usneoides – the last word meaning “like Usnea”).

Galápagos guide, Phillipi Degel, wearing an Usnea beard.

Can you identify three types of lichens in this slide?

Christmas Wreath Lichen, Cryptothecia rubrocincta. This occurs in the southern U.S. and in the tropics.

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