Tag Archives: Fungi

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.

Saccharomyces_cerevisiae

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:

Botrytis_cinerea

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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Friday Fellow: Common Stinkhorn

by Piter Kehoma Boll

Today things are getting sort of pornographic again. Some time ago I introduced a plant whose flowers resemble a woman’s vulva, the asian pigeonwing, and now is time to look at something of the other sex. And what could be better than the shameless penis? That’s the translation of the scientific name of this mushroom, Phallus impudicus, whose common name in English is much more discrete: common stinkhorn.

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Standing proud and shameless. Photo by flickr user Björn S…*

Found throughout Europe and parts of North America in deciduous woods, the common stinkhorn is easily recognizable for its phallic shape and even more for its foul smell that resembles carrion. This odor attracts insects, especially flies, that carry the spores away. This is a different method from the one used by most fungi, which simply release the spores in the air. Some people may mistake the common stinkhorn for morels (genus Morchella) but the two are completely unrelated, being from different phyla.

Despite the foul smell, the common stinkhorn is edible, especially in its first stages of development, when it resembles an egg. Due to its phallic shape, it is also seen as an aphrodisiac in some culture, as it is common with genitalia-shaped lifeforms.

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The immature fruiting body of Phallus impudicus is the most commonly eaten form. Photo by Danny Steven S.*

The common stinkhorn seems to have some anticoagulant properties and can be used for patients susceptible to thrombosis in the veins, such as patients treating breast cancer.

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ResearchBlogging.orgReferences:

Kuznecov, G., Jegina, K., Kuznecovs, S., & Kuznecovs, I. (2007). P151 Phallus impudicus in thromboprophylaxis in breast cancer patients undergoing chemotherapy and hormonal treatment The Breast, 16 DOI: 10.1016/s0960-9776(07)70211-4

SMITH, K. (2009). On the Diptera associated with the Stinkhorn (Phallus impudicus Pers.) with notes on other insects and invertebrates found on this fungus. Proceedings of the Royal Entomological Society of London. Series A, General Entomology, 31 (4-6), 49-55 DOI: 10.1111/j.1365-3032.1956.tb00206.x

Wikipedia. Phallus impudicus. Available at <https://en.wikipedia.org/wiki/Phallus_impudicus&gt;. Access on March 7, 2017.

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Friday Fellow: Black Bread Mold

by Piter Kehoma Boll

Today’s Friday Fellow lives in our houses and our gardens, among our food and our crops. And every time we notice it, we get upset, because it means that something we were supposed to eat is now spoiled. Its name is Rhizopus stolonifer, or black bread mold.

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The black bread mold growing on a peach. Photo by University of Georgia Plant Pathology Archive.*

Having a worldwide distribution, the black bread mold is mainly saprotrophic, growing on decaying fruits and bread. During its reproductive phase, it can be noticed as a black and hairy mold, as in the photo above. Eventually, this species can also cause an infection in human face and oropharynx, but most commonly it can be a pathogen of many plant species, thus being of economic concern.

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A closer look at the sporangia of Rhizopus stolonifer. Photo by Stanislav Krejčík.*

The black bread mold is a fungus of the order Mucorales, known as pin molds because their sporangia (the structures that contain the asexual spores) remember a pin. These sporangia, which are black, are what one usually notice growing on decaying food. When the sporangia are mature, they release spores of two kinds that germinate and originate two kinds of hyphae (known as + and -) and when two hyphae of opposite type come into contact, they fuse and create a zygospore, which then grows to originate new sporangia.

Due to its importance as an economic pest, there are many studies trying to find ways to get rid of it and very few studies trying to understand the fascinating things that it hides. What a pity.

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ResearchBlogging.orgReferences:

EOL – Encyclopedia of Life: Rhizopus stolonifer. Available at <http://eol.org/pages/2944808/overview >. Access on January 14, 2107.

Hernández-Lauzardo, A., Bautista-Baños, S., Velázquez-del Valle, M., Méndez-Montealvo, M., Sánchez-Rivera, M., & Bello-Pérez, L. (2008). Antifungal effects of chitosan with different molecular weights on in vitro development of Rhizopus stolonifer (Ehrenb.:Fr.) Vuill Carbohydrate Polymers, 73 (4), 541-547 DOI: 10.1016/j.carbpol.2007.12.020

Wikipedia. Black bread mold. Available at <https://en.wikipedia.org/wiki/Black_bread_mold >. Access on January 14, 2017.

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Friday Fellow: Witch’s Butter

ResearchBlogging.orgby Piter Kehoma Boll

Last week I introduced a cyanobacteria that reminds me of my childhood and that is commonly known as witch’s jelly or witch’s butter. But witch’s butter is also the common name of fungus, so I thought it would be interesting to introduce it today. Its scientific name is Tremella mesenterica.

tremella_mesenterica

Witch’s butter on dead wood. Photo by Jerzy Opiała.*

Also known as yellow brain, yellow trembler or golden jelly fungus, the witch’s butter is found in all continents and appears as a lobed and curly jelly material growing on dead wood and may be mistaken as a saprobic species, a wood decomposer, but that’s not true. The witch’s butter is actually a parasite of saprobic fungi of the genus Peniophora, such as the rosy crust Peniophora incarnata.

The witch’s butter is edible, but usually considered tasteless. Some preliminary results indicate that it may reduce blood glucose levels, therefore having the potential do be developed into a hypoglycemic agent for the treatment of diabetes mellitus.

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References:

Lo, H., Tsai, F., Wasser, S., Yang, J., & Huang, B. (2006). Effects of ingested fruiting bodies, submerged culture biomass, and acidic polysaccharide glucuronoxylomannan of Tremella mesenterica Retz.:Fr. on glycemic responses in normal and diabetic rats Life Sciences, 78 (17), 1957-1966 DOI: 10.1016/j.lfs.2005.08.033

Wikipedia. Tremella mesenterica. Available at <https://en.wikipedia.org/wiki/Tremella_mesenterica&gt;. Access on September 22, 2016.

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Friday Fellow: Rosy Crust

ResearchBlogging.orgby Piter Kehoma Boll

If you are walking through a forest in Europe you may find the bark of some trees covered by a thin rosy or orange crust. Commonly known as rosy crust, its scientific name is Peniophora incarnata.

peniophora_incarnata

Rosy crust growing on a dead branch. Photo by Jerzy Opioła.*

As with most fungi, the rosy crust is saprobic, i.e., it feeds on dead material, in this case dead wood, so that it is more commonly found attached to dead branches. It affects a variety of plant species, especially flowering plants, but may eventually grow on pine trees.

Sometimes considered a pest because of its ability to rotten wood, the rosy crust has also some interesting benefits. It has shown to have antimicrobial activity, being a potential source for the production of antibiotics, and is also able to degrade some carcinogenic products used to treat wood, such as polycyclic aromatic hydrocarbons.

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References:

EOL – Encyclopedia of Life. Peniophora Incarnata – Rosy Crust. Available at: <http://www.eol.org/pages/1009530/overview&gt;. Access on September 22, 2016.

Lee, H., Yun, S., Jang, S., Kim, G., & Kim, J. (2015). Bioremediation of Polycyclic Aromatic Hydrocarbons in Creosote-Contaminated Soil by Peniophora incarnata KUC8836 Bioremediation Journal, 19 (1), 1-8 DOI: 10.1080/10889868.2014.939136

Suay, I., Arenal, F,, Asensio, F. J., Basilio, A., Cabello, M. A., Díez, M. T., García, J. B., González del Val, A., Gorrochategui, J., Hernández, P., Peláez, F., & Vicente, M. F. (2000). Screening of basidiomycetes for antimicrobial activities Antonie van Leeuwenhoek, 78 (2), 129-140 DOI: 10.1023/A:1026552024021

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