Fungus Fact Friday

Tagged: life cycle

follow fungi from spore to mushroom

0

Fungus Fact

#011: Characteristics of Fungi

What is a fungus?  That question has been answered many ways over the years, reflecting an evolving understanding of this strange group of organisms.  Initially, fungi were classified as a class in kingdom Plantae.  As our understanding of the chemistry, life history, and evolution of fungi improved, Fungi was elevated to the rank of kingdom.  Kingdom Fungi is placed in domain Eukarya and belongs to the major clade Opisthokonta.  Opisthokonta also includes the kingdom Animalia, which makes animals close relatives of the fungi.  But going beyond taxonomic definitions, what makes a fungus a fungus?  It’s hard to answer that question because the fungal kingdom is very diverse and there are many similar organisms in other kingdoms.  As a simple answer, Fungi are heterotrophic filamentous (or unicellular) eukaryotes with a chitin cell wall that reproduce by spores and digest their food externally.

1

Fungus Fact

#019: Apiosporina morbosa, Black Knot

And now for something completely different: how to recognize different types of trees from quite a long way away.*  Black Cherry (Prunus serotina) is the easiest tree in eastern North America to identify, thanks to the fungus Apiosporina morbosa, commonly known as Black Knot.  Most Black Cherry trees are infected with A. morbosa, which causes dark swellings on branches and trunks.  Older tree trunks are often marred by large swellings caused by A. morbosa that are up to twice the size of the trunk.  These “knots” are easy to spot from a distance (especially in winter), so take advantage of this and amaze your friends by pointing out Black Cherry trees without relying on bark, leaves, or other details!  On twigs and smaller branches, Black Knot makes the branches lumpy and thickened in places, looking remarkably like “dried cat poop on a stick” (thank Michael Kuo for that apt analogy).

1

Fungus Fact

#085: Schizophyllum commune, The Mushroom with Over 28,000 Sexes

If you think dating is complicated in the human world, be glad you’re not Schizophyllum commune.  Humans have two basic biological sexes and six or more gender identities to deal with, but S. commune has to choose from over 28,000 different sexes!  This overly complex system is based on genetics and the weird way fungi reproduce.  But this isn’t just a weird example, it’s also one of the most common mushrooms in the world.  You can probably find the mushroom out now, and identify it easily.  The little white mushroom is easily distinguished by its small gills, which appear to be split lengthwise.  This unique feature has led to its common name, the “Split Gill” or sometimes “Common Split Gill.”

Massospora cicadina infected cicada 0

Fungus Fact

#221: Massospora cicadina

It’s hard being an insect. Despite being numerous, insects have many predators, have to deal with human pesticides and cars, and are susceptible to dreadful fungal pathogens. Some of these entomopathogenic fungi take control of their hosts’ bodies in innovative but disturbing ways. One such fungus is Massospora cicadina, which infects periodical cicadas (Magicicada spp., which appear in eastern North America every 13 or 17 years). After spending over a decade in the soil waiting for its hosts to emerge, the fungus infects the cicadas and causes their abdomens to pop off. The cicadas then fly around and try to mate with each other, spreading the fungal infection both through the air and through contact. It’s hard to imagine a more horrific sexually transmitted infection, even in the insect world.

Cedar-Apple Rust telial horns 8

Fungus Fact

#087: Gymnosporangium juniperi-virginianae, Cedar-Apple Rust

Gymnosporangium juniperi-virginianae is a rust fungus known as Cedar-Apple Rust (sometimes abbreviated to CAR) that causes disease in Eastern Red Cedar and in apple trees. This fungus is unique among rusts because it produces large fruiting bodies. On cedar trees, the fruiting bodies resemble lumpy brown golf balls with long gelatinous orange tentacles bursting out of them. On apple trees, the disease causes more damage but produces only orangish spots. The complex life cycle of Cedar-Apple Rust means the fungus is easy to control, although these control methods resulted in a legal case that was argued before the Supreme Court of the United States!

Wheat Leaf Rust, Wheat Stripe Rust, and Wheat Stem Rust 1

Fungus Fact

#208: Rust Diseases of Wheat

Wheat is the most widely grown crop in the world and is a staple food for billions of people. Diseases affecting wheat are therefore of utmost importance to food security. Some of the most destructive and difficult wheat diseases are the rusts. Wheat rust comes in three varieties: Leaf Rust, Stem Rust, and Stripe Rust, each caused by a different species of fungus. These all look slightly different but all cause rust-colored blemishes on wheat surfaces. The three species are closely related and have nearly identical life cycles. Despite this, managing the diseases is complicated and requires using resistant wheat strains, proper cultural practices, and fungicides.

Inky cap gill face 36

Fungus Fact

#013: Characteristics of Division Basidiomycota

Division Basidiomycota (also called Phylum Basidiomycota) accounts for about 37% of all described fungal species. This division contains the fungi that people are most familiar with. The classic “Mario mushroom” (based on Amanita muscaria), the grocery store button mushroom and other varieties of Agaricus bisporus, shiitakes, oyster mushrooms, and even the major “magic mushrooms” are all basidiomycetes. However, the Basidiomycota also include rusts and smuts, which are economically important plant pathogens, some yeasts, and a few lichenized fungi. Like the Ascomycota, the Basidiomycota fill a variety of different ecological roles. Many form mycorrhizas with plants, others parasitize plants, a lot decompose organic material, and some live in a variety of symbioses with insects. The Basidiomycota are commonly referred to as “basidiomycetes,” “basidios,” or “club fungi.”

arbuscules in root 2

Fungus Fact

#015: Characteristics of Division Glomeromycota

The Glomeromycota are unusual and poorly understood organisms. Fungi from this division rarely produce easily visible structures and cannot be grown without a plant host, so investigating them is very difficult. Glomeromycotan fungi are some of the most important fungi on Earth because they form arbuscular mycorrhizas, which provide essential nutrients to the vast majority of terrestrial plants.

#132: Microbotryum spp., the Anther Smuts 0

Fungus Fact

#132: Microbotryum spp., the Anther Smuts

Of all the sexually transmitted infections in the world, the anther smuts are probably the most bizarre. Fungi in the genus Microbotryum infect plants in the pink family (Caryophyllaceae) as well as a few other species.  When a plant infected with an anther smut tries to produce flowers, the fungus hijacks the process and forces the plant to make anther-like structures filled with fungal spores instead of pollen.  The spores are primarily transmitted to new flowers by pollinators, but can also be spread by wind or splashing raindrops.

#131: Class Ustilaginomycetes, Smut Fungi 0

Fungus Fact

#131: Class Ustilaginomycetes, Smut Fungi

These fungi are obligate plant pathogens with life cycles similar to the rust fungi. Thankfully, the smut fungi have much simpler life cycles: only one host and only two spore types.  To make matters easier, smut fungi only infect flowering plants (angiosperms), with just five known exceptions out of the over 1,400 described species.  Wondering about their common name?  Although the word “smut” has come to mean “something obscene,” it originally meant “dirt” or “excrement.”  Smut fungi produce copious amounts of powdery, black spores, which look like dirt en masse.  “Smutted wheat,” therefore, is wheat that has had its seeds replaced by the dirt-like spores of a smut fungus.