Category Archives: Fungi

Friday Fellow: Pear Rust

by Piter Kehoma Boll

Beautiful and deadly, today’s fellow appears during spring as gelatinous orange projections coming out of juniper trees in Europe and North America. Its name is Gymnosporangium sabinae, commonly known as the pear rust.

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The jelly-like horns of the pear rust on a juniper tree. Photo by Mark Sadowski.*

The pear rust is a basidiomycete, i.e., a fungus of the phylum Basidiomycota, therefore related to the common mushrooms, but belonging to a different class, the Puccioniomycetes.

During winter, the pear rust remains in a resting state inside branches and twigs of juniper trees. After wet days in spring, the fungus sprouts and appears as horn-like growths covered by an orange gelatinous mass, which are called telia. The telia produce wind borne spores called teliospores that can infect pear trees.

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The pear rust on pear leaves. Photo by Jan Homann.

Once reaching the pear tree, the teliospores germinate and infect the leaves of the new host. The infection appears in summer as rust-colored spots on the leaves, hence the name pear rust. In heavily infected plants, the effects of the pear rust can be severe, sometimes causing the plant to lose all its leaves.

In pear trees, the fungus produce reproductive structures known as aecia. They come out from the underside of pear leaves and produce spores called aeciospores, which are able to infect new juniper trees.

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The aecia coming out of the rust on a pear tree. Photo by H. Krisp.**

Due to the economic importance of pear trees to humans, the pear rust is a species of great concern. Some countries have policies intended to reduce the spread of the disease, such as preventing transportation of juniper trees from areas known to have the fungus to areas in which it is unknow. In areas where the fungus exist, the solutions to reduce the damage include the use of chemical fungicides, the removal of infected branches in juniper trees and sometimes the removal of any juniper tree around the areas where pear trees are cultivated.

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References:

Fraiture, A.; Vanderweyen, A. (2011) Gymnosporangium sabinae: such a beautifiul disease. Scripta Botanica Belgica 11: 193–194.

Ormrod, D. J.; O’Reilly, H. J.; van der Kamp, B. J,; Borno, C. (1984) Epidemiology, cultivar susceptibility, and chemical control of Gymnosporangium fuscum in British Columbia. Canadian Journal of Plant Pahology6: 63–70.

Wikipedia. Gymnosporangium sabinae. Available at < https://en.wikipedia.org/wiki/Gymnosporangium_sabinae >. Access on April 27, 2018.

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Friday Fellow: Irregular Earth Tongue

by Piter Kehoma Boll

Let’s move back to the land this week and look very close to the ground, and very close to the base of one of the main phyla of fungi, the Ascomycetes.

With the name Neolecta irregularis, usually adapted as the common name “irregular earth tongue”, this fungus can be identified in the woods of North America and Japan by its irregular and unbranched yellow fruiting bodies that appear sprouting from the ground near trees.

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Fruiting bodies of Neolecta irregularis in the USA. Photo by Walt Sturgeon.*

At first the irregular earth tongue looks just like any other fungus, but it holds a secret to the evolution of the ascomycetes, the largest phylum of these organisms. The diverse phylum Ascomycota includes both unicellular fungi, such as yeasts, which do not produce fruiting bodies, and multicellular complex fungi, usually called “mushrooms”, with well-developed fruiting bodies. For a long time it was thought that the ancestor of the ascomycetes was a yeast-like species, and that large and complex fungi evolved only later. The genus Neolecta, however, came to challenge that.

Molecular studies have revealed that the genus Neolecta is not closely related to any other ascomycete that produce fruiting bodies, but holds a basal position within the phylum, grouping with fission yeasts and other unicellular groups. This hints to the possibility that the first ascomycete was actually much more complex than previously thought and that the yeast lineages as a result of simplification.

However, there is still much to learn from the irregular earth tongue and its relatives. Most of its ecology and life cycle are still a mystery. We don’t even know for sure if it is a parasite or what. Research has to go on!

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References:

Landvik, S. (1996) Neolecta, a fruit-body-producing genus of the basal ascomycetes, as shown by SSU and LSU rDNA sequences. Mycological Research 100(2): 199-202. DOI: 10.1016/S0953-7562(96)80122-5

Redhead, S. A. (1977) The genus Neolecta (Neolectaceae fam. nov., Lecanorales, Ascomycetes) in Canada. Canadian Journal of Botany 55(3): 301-306. DOI: 10.1139/b77-041

Wikipedia. Neolecta. Available at < https://en.wikipedia.org/wiki/Neolecta >. Access on February 22, 2018.

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Friday Fellow: Reishi Mushroom

by Piter Kehoma Boll

The first Friday Fellow of 2018 is here, and it is a beloved parasite from the Far East. This lovely mushroom is scientifically known as Ganoderma lucidum and has no native common name in English, being usually called the reishi mushroom, from its Japanese name 霊芝 (reishi), or lingzhi mushroom, from its Chinese name 靈芝 (língzhī).

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The beautiful and shiny kidney-shaped reishi. Photo by Wikimedia user Mokkie.*

The reishi mushroom, as other species in the genus Ganoderma and in the order Polyporales, grows on tree trunks, usually parasitizing live trees and continuing to grow on them after they die. The mature fruiting body is kidney-shaped and may or may not have a stalk, which is displaced to the side, below the concave side of the cap. The cap has a red-varnished color with a lighter rim. It is easily mistaken for some of its closest relatives, such as Ganoderma tsugae and G. lingzhi.

Traditionally used in Chinese medicine, the reishi mushroom was considered the “mushroom of immortality” and said to improve the heart and the mind. Recently, it has demonstrated, in laboratory studies, to have many potential uses for the treatment of different illnesses. For example, their fruiting bodies release polysaccharides that showed the ability to increase the cytokine production of human white blood cells, which increase anti-tumor activities. Other studies have identified compounds with potential anti-HIV activity and the ability to reduce the levels of blood sugar.

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References:

El-Mekkawy, S.; Meselhy, M. R.; Nakamura, N.; Tezuka, Y.; Hattori, M.; Kakiuchib, N.; Shimotohnob, K.; Kawahatac, T.; Otakec, T. (1998) Anti-HIV-1 and anti-HIV-1-protease substances from Ganoderma Lucidum. Phytochemistry49(6): 1651–1647. https://doi.org/10.1016/S0031-9422(98)00254-4

Wang, S.-Y.; Hsu, M.-L.; Hsu, H.-C., Lee, S.-S.; Shiao, M.-S.; Ho, C.-K. (1997) The anti-tumor effect of Ganoderma Lucidum is mediated by cytokines released from activated macrophages and T lymphocytes. International Journal of Cancer70(6): 699–705. Doi: 10.1002/(SICI)1097-0215(19970317)70:6<699::AID-IJC12>3.0.CO;2-5

Wang, Y.-Y.; Khoo, K.-H.; Chen, S.-T.; Lin, C.-C.; Wong, C.-H.; Lin, C.-H. (2002) Studies on the immuno-Modulating and antitumor activities of Ganoderma lucidum (Reishi) polysaccharides: functional and proteomic analyses of a fucose-Containing glycoprotein fraction responsible for the activities. Bioorganic & Medicinal Chemistry, 10(4): 1057–1062. https://doi.org/10.1016/S0968-0896(01)00377-7

Wikipedia. Lingzhi mushrom. Available at: < https://en.wikipedia.org/wiki/Lingzhi_mushroom >. Access on December 31, 2017.

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Friday Fellow: Yellow Morel

by Piter Kehoma Boll

Time for our next fungus, and this time it is a delicious one, or at least I think so, as I have never eaten it. Scientifically known as Morchella esculenta, its common names include common morel, yellow morel, true morel or simply morel.

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A fruiting body of the yellow morel in France. Photo by Henk Monster.*

Common in North America and Europe, as well as in some parts of Asia, especially in wooden areas, the yellow morel is a popular edible fungus of the phylum Ascomycota, so it is not closely related to the more common mushrooms, but it is a relative of the truffles, for example.

Morels are usually easily recognizable due to their peculiar appearance. Appearing during spring, their fruiting body is more or less oval in shape, covered with irregular pits and ridges, and hollow.

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An open morel showing its hollowness. Photo by Wikimedia user 00Amanita00.*

Although being one of the most highly prized mushrooms, morels can give you some undesirable effects, such as gastrointestinal problems, if eaten raw or if too old. So, it is advisable to eat young mushrooms and at least blanching them before consumption. As they are hollow, it is common to eat them stuffed with vegetables or meat.

Pharmacological and biochemical studies revealed that the yellow morel has many healthy properties, such as the presence of antioxidants and substances that stimulate the immune system, as well as anti-inflammatory and antitumour properties. It is certainly a food that is worth to include in our diet, too bad that is tends to be kind of expensive…

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References:

Duncan, C. J. G.; Pugh, N.; Pasco, D. S.; Ross, S. A. (2002) Isolation of galactomannan that enhances macrophage activation from the edible fungs Morchella esculentaJournal of Agricultural and Food Chemistry, 50(20): 5683–5695. DOI: 10.1021/jf020267c

Mau, J.-L.; Chang, C.-N.; Huang, S.-J.; Chen, C.-C. (2004) Antioxidant properties of methanolic extracts from Grifola frondosa, Morchella esculenta and Termitomyces albuminosus mycelia. Food Chemistry, 87(1): 111-118.
https://doi.org/10.1016/j.foodchem.2003.10.026

Nitha, B.; Meera, C. R.; Janardhanan, K. K. (2007) Anti-inflammatory and antitumour activities of cultured mycelium of morel mushroom, Morchella esculentaCurrent Science, 92(2): 235–239.

Wikipedia. Morchella esculenta. Available at < https://en.wikipedia.org/wiki/Morchella_esculenta >. Access on October 31, 2017.

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Friday Fellow: Brown spot of maize

by Piter Kehoma Boll

I’ll continue the parasite trend from last week, but this time shifting from human parasite to maize parasite, and from a prokaryotic to a eukaryotic parasite. So let’s talk about Physoderma maydis, commonly known as the brown spot of maize or brown spot of corn.

The Brown spot of maize is a fungus of the division Blastocladiomycota that infects corn (or maize) plants. Its common name comes from the fact that it causes a series of brown spots on the leaves of an infected plant.

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The brown spots seen on this corn leaf are due to an infection by Physoderma maydis. Credits of the photo to Clemson University – USDA Cooperative Extension Slide Series.*

The life cycle of the brown spot of maize is as complex as that of many fungi. The infection of the plants occur through spores that remain in the soil during winter and are carried to the host by the wind, germinating in the rainy season. The germinated spores produce zoospores, flagellated spores able to swim. Swiming through the maize leaf, the zoospores infect single cells and produce zoosporangia at the surface of the leaf. The zoosporangia release new zoospores that infect new cells. In late spring and summer, the zoospores produce a thallus growing deep inside the maize leaf that infects many cells and produces thick-walled sporangia. After the plants dies and the leaves become dry and broke, the sporangia are released and reach the soil, where they wait for the next spring to restart the cycle.

The brown spot of maize is a considerable problem for maize crops in countries with abundant rainfall. Heavy infections may kill the maize plant or severely reduce its fitness before the ears are ready to be harvested. Although fungicides may help in slowing down the infectio throughout the crops, one of the most efficient ways to reduce the damage is to destroy, usually by fire, the remains of the last harvest.

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References:

Olson, L. W.; Lange, L. (1978) The meiospore of Physoderma maydis. The causal agent of Physoderma disease of maize. Protoplasma 97: 275–290. https://dx.doi.org/10.1007/BF01276699

Plantwise Knowledge Bank. Brown spot of corn (Physoderma maydis). Available at: < http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=40770&gt;. Access on Agust 7, 2017.

Robertson, A. E. (2015) Physoderma brown spot and stalk rot. Integrated Crop Management News: 679. http://lib.dr.iastate.edu/cropnews/679/

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Friday Fellow: Baker’s Yeast

by Piter Kehoma Boll

Living along humans for centuries, today’s Friday Fellow is certainly one of the most beloved fungi. Scientifically known as Saccharomyces cerevisiae, its common names in English include baker’s yeast, brewer’s yeast or ale’s yeast.

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Saccharomyces cerevisiae under the scanning electron microscope. Photo by Mogana Das Murtey and Patchamuthu Ramasamy.*

Under the microscope, the cells of this single-celled species are ellipsoid or sphere-shaped and usually show small buds from new cells growing from the larger one. But you may have seen this species being sold as tablets or grains in the supermarket, as they are used to make bread and many alcoholic bevarages, such as wine and beer, but the baker’s yeast is much more interesting than just that.

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Grains of dried but yet alive baker’s yeast as it is sold commercially.

The cells of the baker’s yeast occur naturally on ripe fruits, such as grapes, and this was likely the original source of the strains currently cultivated by humans. The yeast reaches the fruits through many wasp species that have it growing in their intestines, an ideal environment for the fungus’ sexual reproduction.

As it is easily cultivated in the lab and has a short generation time, the baker’s yeast has become one of the most important model organisms in current biological studies. It was, in fact, the first eukaryotic organism to have its whole genome sequenced more than 20 years ago.

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Saccharomyces cerevisiae growing on solid agar in the lab. Photo by Conor Lawless.**

More than giving us food and drink, this amazing yeast has increased our understanding of gene expression, DNA repair and aging, among many other things. Live long the yeast!

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References:

Giaever, G.; Chu, A. M.; Ni, L.; Connelly, C. et al. (2002) Functional profiling of the Saccharomyces cerevisiae genome. Nature 418 (6896): 387-391.

Herskowitz, I. (1988) Life cycle of the budding yeast Saccharomyces cerevisiae. Microbiological Reviews 52 (4): 536-553.

Wikipedia. Saccharomyces cerevisiae. Available at < https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae >. Access on July 25, 2017.

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Friday Fellow: Gray Mold

by Piter Kehoma Boll

Today’s Friday Fellow will show you how beauty is only a matter of perspective. Being an ascomycete fungus, it is commonly known as gray mold and is usually found growing on decaying vegetables, especially fruits such as the strawberry in the photo below:

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Gray mold growing on a strawberry. Most people would not see it as a beautiful image. Photo by Wikimedia user Rasbak.*

The gray mold has a controversial biological nomenclature, as many other fungi. The most common name is Botrytis cinerea used for its asexual stage (anamorph), which is the most common. Its sexual stage (teleomorph) is known as Botryotina fuckeliana. I guess this issue, which was common in naming fungi with rare or unknown occurrences of sexual stage, has already been settled, but as I’m not a taxonomist of fungus, I cannot speak much on the subject.

More than only having a controversial name, this fungus has also a controversial interaction with humans. It is a notable pest in wine grapes and may lead to two different infections on them. One of those is called “grey rot” and happens under wet conditions, leading to the loss of the grapes. The other is called “noble rot” and is a beneficial form of the infection that happens when the wet condition is followed by a dry one and produce a fine and sweet vine due to the concentration of sugars in the grape.

Out of the vine world, however, the gray mold is not something that you want growing on your crops. As as it attacks more than 200 species, many of them being important food crops, there is a big interest in developing strategies to reduce the damage it causes. And these strategies include the use of pesticides, plant essential oils or even other organisms that may parasitize the gray mold.

But one cannot deny that if you look closer, even the gray mold is beautiful:

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A beautiful tiny forest of gray mold on a strawberry. Photo by Macroscopic Solutions.**

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ResearchBlogging.orgReferences:

Wikipedia. Botrytis cinerea. Available at <https://en.wikipedia.org/wiki/Botrytis_cinerea&gt;. Access on June 2, 2017.

WILLIAMSON, B., TUDZYNSKI, B., TUDZYNSKI, P., & VAN KAN, J. (2007). Botrytis cinerea: the cause of grey mould disease Molecular Plant Pathology, 8 (5), 561-580 DOI: 10.1111/j.1364-3703.2007.00417.x

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