Fungi; Ascomycota; Sordariomycetes; Hypocreales; Clavicipitaceae [Others may be used. Use NCBI link to find]
'Claviceps purpurea,' Common Name: rye ergot fungus, Anamorph: Sphacelia segetum''
Description and Significance
The fungus Claviceps purpurea is responsible for causing the fungal disease ergot of rye. Claviceps is capable of replacing the seeds of many forage grasses and cereal grains with alkaloid containing sclerotia. These sclerotia, which are purplish-brown masses of hardened mycelia, can cause human poisoning, called ergotism, when consumed. It is hypothesized that ergotism caused "bewitchment," the strange behavior reported during the Salem Witch Trials (3). Symptoms documented included hallucinations, vomiting, psychosis, and delirium . Of the approximate 40 species of Claviceps described, C. purpurea is of the most importance due to its potential for economic loss in rye crops and its significant toxicity to both humans and animals (1).
Life Cycle, Cell Structure, Metabolism
C. purpurea is unique in that it only infects the ovaries of mostly young unfertilized plants (1). Ascospores are dispersed by wind and land on plant stigma alongside pollen grains. These spores infect the ovary and hyphae begin to develop. Following hyphal development, conidia are formed and dispersed with the help of insects who are attracted to a sticky honeydew created by a combination of fungal conidia and sap from the host plant. The infected plant ovary is then replaced by sclerotia, or ergot, which consists of hardened mycelia used for protection, dormancy, and survival. When the crop is harvested, the sclerotia is harvested along with the grain, leading to contamination. Contamination comes from alkaloids present in the sclerotia, which are categorized into three groups: clavines, ergopeptines, and amides of lysergic acid, the latter being a derivative used to produce LSD (4).
Organism: Claviceps purpures Strain: 20.1 Genome GC: 0.52 CDS GC: 0.55 non-Rpt-IG GC: 0.50 Rpt GC: 0.50 (5)
Ecology and Pathogenesis
C. purpurea has been known to infect over 400 grass and cereal species and can found in temperate regions around the world (2). Though the loss of crops due to ergot is typically low, only 5-10% (2), the health effects that consumption can have on humans can be severe. In historical accounts ergotism caused hallucinations, fever, convulsions, loss of fertility, miscarriage, and loss of limbs in humans. Due to modern management strategies, the risk of exposure to ergotism today is low in comparison to historical times (1). Today, compounds isolated from Clavicepshave been used to create medicines to treat migraine headaches, heavy menstrual bleeding, bleeding after child-birth, and neurological and cardiovascular disorders.
1. Schumann, G.L. and Uppala, S. (2000). Ergot of rye. The Plant Health Instructor. DOI: 10.1094/PHI-I-2000-1016-01 Updated 2017. Retrieved December 2018 from http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/pages/ergot.aspx 2. Miedaner, T., & Geiger, H. H. (2015). Biology, genetics, and management of ergot (Claviceps spp.) in rye, sorghum, and pearl millet. Toxins, 7(3), 659-78. doi:10.3390/toxins7030659 Retrieved December 2018 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4379517/ 3.Matossian, Mary (July–August 1982). "Ergot and the Salem Witchcraft Affair". American Scientist. 70 (4): 355–7. Bibcode:1982AmSci..70..355M Retrieved December 2018 from https://en.wikipedia.org/wiki/Ergotism 4. Money, Nicholas (2015) The Fungi. Elsevier Publishing Retrieved December 2018 from https://www.sciencedirect.com/science/article/pii/B9780123820341000128?via%3Dihub 5. Schardl, C.L., (2013). Plant-Symbiotic Fungi as Chemical Engineers: MultiGenome Analysis of the Clavicipitaceae Reveals Dynamics of Alkaloid Loci.PLOS Genetics.February 2013 | Volume 9 | Issue 2 | e1003323. Retrieved December 2018 from www.plosgenetics.org
Page authored by Gayle J. Nance, student of Dr. Marc Orbach, University of Arizona .