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.
Note: This is an archived post. Read the current version of this post here. 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,...
Imagine for a moment that it is the late 17th century and you live in rural America. Your day starts off like any other day: you wake up, have breakfast, and begin working on your farm. However, before too long your daughter starts behaving oddly. At first she just seems agitated, but her symptoms quickly escalate. She convulses, hides under the table, yells unintelligibly, and complains of a prickly sensation in her arms and legs. Terrified, you call for the town doctor. The doctor has never seen a disease like this before and cannot find anything physically wrong with your daughter. After a while, he comes up with the only possible cause: witchcraft. Just then, one of your neighbors bursts in, looking for the doctor. His daughter has been exhibiting the same symptoms! You look at his frightened face and realize what you have to do: in order to protect...
On this first anniversary of Fungus Fact Friday, I would like to introduce a new topic which I have labeled, “That’s Not a Fungus!” Kingdom Fungi has gone through a lot of changes over the years. Many organisms that were once included in the kingdom have since been exiled. There are two reasons why I think these organisms are worth discussing in FFF. First, they were once studied by mycologists, in some cases contributing more to our understanding of fungi than the fungi themselves. Second, it is important to know what a fungus is as well as what a fungus is not. Slime molds are no longer considered fungi because really the only things those two groups have in common are a similar life cycle and “strange” fruiting bodies. Slime molds do not have cell walls and grow as neither hyphae nor yeast. They also engulf (phagocytose) their food before...
Note: This is an archived post. You can find the current version of this post here. Coffee Rust (la roya in Spanish) is a disease of coffee plants that is caused by the fungus Hemileia vastatrix. If you enjoy a fine cup of coffee, then this is one fungus you should be very interested in. The Coffee Rust is currently ravaging coffee trees in Central America, where 60% to 75% of the region’s crops are infected with the pathogen. The result of this has been a 15% drop in Central America’s coffee output and a corresponding loss of more than 100,000 jobs over the last two years. The high-end Arabica trees are particularly susceptible to the disease. America’s major coffee producers have been able to find enough coffee to meet demand without a noticeable impact on price*, but smaller, specialty brewers are having a harder time. And we haven’t seen...
Phylum microspora (not to be confused with the green algae genus Microspora) contains some of the most unusual fungi: the microsporidia. There are over 1200 described species in this phylum (and that is only a fraction of their biodiversity), divided into about 150 genera (plural of genus). These organisms were originally thought to be protozoans, but recent DNA studies have demonstrated that they belong with the fungi. The microsporidia are all obligate parasites of animals and have an extremely reduced cell structure. They do not have mitochondria, so they can only grow and reproduce within the cells of their host. Their very resistant spores persist in the environment for a long time and allow them to spread from one animal to another. The spores are 1 to 40 micrometers long, making them the smallest eukaryotes. The spores are rougly oval and have a cell wall made of chitin that is...
It has recently been demonstrated that the four subphyla historically classified as zygomycota do not make up a monophyletic group. As a result, the phylum zygomycota is no longer used. However, it has not yet been replaced by other phyla. The terms “zygomycota” and “zygomycetes” are therefore only used informally to reference this diverse group of fungi. The distinctive characteristic of the zygomycetes is their method of sexual reproduction (if a sexual stage exists). Their hyphae are almost always haploid. When two compatible (and haploid) hyphae meet they form gametangia, which fuse and become diploid. However, the diploid hypha is immediately isolated from the rest of the fungus. This isolated hypha then undergoes meiosis and develops into one zygospore. The zygospore is usually thick-walled and undergoes an obligatory period of dormancy before it germinates. This helps the spore survive for a long time in adverse conditions. Zygos also tend to...
Note: This is an archived post. You can find the current version of this post here. The Glomeromycota are all fungi which form arbuscular mycorrhizae (AM). Mycorrhizae are a type of mutualism with plants where the fungus gets sugars and gives up hard-to-extract nutrients (especially phosphorous). AM fungi accomplish this by forming structures within the plant’s root cells while not causing a disease reaction. Most land plant species form AM, and only a few families are considered non-mycorrhizal. AM fungi tend to be generalists, colonizing a variety of different plant species. Each plant is usually colonized by multiple AM species. This mycorrhizal network has a variety of different roles in an ecosystem. It supplies nutrients to plants, determines what species make up an ecosystem’s plant community, and allows other plants (like orchids and Indian pipe) to parasitize larger plants via the network. A recent study has also suggested that plants...
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