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!
Tagged: life cycle
follow fungi from spore to mushroom
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.
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.”
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.
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.
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.
Rust fungi – which are so named because of their characteristic, rust-colored spores – have the most complex life cycles of any fungi. These fungi are all obligate plant parasites and most have two hosts. To successfully cycle from one host to the other over the course of a year, rust fungi produce up to five different types of spores.
Commonly known as the Split Gill, this little mushroom is easily distinguished by its small gills, which appear to be split lengthwise. The Split Gill is a notable mushroom because of its unusual morphology, ecology, and genetics. Before I get into the bizarre world of fungal sexes, I would like to describe the physical characteristics of this distinctive mushroom.
Frosty Pod Rot, caused by the fungus Moniliophthora roreri, is one of the most significant pathogens of cacao trees (Theobroma cacao). The disease has been around a long time: it was first recognized in Ecuador in 1917 and first described in 1933. roreri likely evolved in Columbia, where the greatest diversity of the species is located and where cultivated cacao trees grow near closely related trees. Up until the 1950’s, Frosty Pod Rot was limited to northwestern South America. Since then, it has spread throughout Central America and into Peru and Venezuela. In these areas, Frosty Pod Rot is the most destructive cacao disease, resulting in the loss of about 30-40% of total production. The disease has not yet made it to Asia or Africa, where most of the world’s chocolate is produced, but it may just be a matter of time.
Lichens are composite organisms made up of two mutualistic, unrelated species: a photosynthetic organism and a fungus. I find that most people don’t really understand what lichens are, and that’s not surprising, considering the definition above. OK, so we’re all familiar with lichens: the green/grey/orange/brown crusts that form on sidewalks/trees/rocks/etc. But what, exactly, are they? Most people would probably classify them as plants or, more specifically, as mosses. This would seem reasonable, as they are often found growing alongside mosses and in other similar habitats. However, this is not the case at all. Lichens are actually composed of two or more separate species growing together as one organism. This unusual type of organism is known as a “composite organism.” Lichens always include one fungal partner (the mycobiont) and at least one photosynthetic partner (the photopiont). The photobiont can be a green alga (kingdom Plantae) or a cyanobacterium (a.k.a. blue-green alga,...