Biology of FUNgi. A look back...

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1 Biology of FUNgi Lecture 09 Filamentous ascomycetes II Perithecial and apothecial ascomycetes A look back... Ascomycete life - asci and ascospores? Four groups of ascomycetes. Laboulbeniales? Cleistothecium? Eurotiales? 1

2 Taxonomy: Phylum (subphylum) Ascomycota Order - Hypocreales Family - Clavicipitaceae is the causal agent of the ergot which refers to (most often) rye grain which has been infected and turns into fungal sclerotium. ascocarp. perithecial ascocarps emerging from the sclerotia Normal grain and Claviceps purpurea infected one turned into a fungal sclerotium. is a typical perithecial ascomycete. Perithecia are embedded into the stroma which emerges from the sclerotium. perithecial ascocarps emerging from the sclerotia Ascocarps are basically an elevated stroma containing perithecia on the outer margin. 2

3 The mycelial, somatic phase colonizes the ovaries of cereals (rye and barley in particular) and native grasses. The infection eventually destroys the whole ovary. Conidiospores are produced in an acervulus-like conidiomata and not aerially dispersed but mixed in a sweet nectary secretion. The conidiospores can be dispersed by insects. sclerotia and healthy grain. life cycle includes overwintering sclerotium. Following spring the ascocarps are produced from the sclerotium. The long ascospores are wind-dispersed and find their ways to the host pistils. sclerotia and ascocarps. 3

4 Why do we need to know about Claviceps? Chronicles from Kanten (Lower Rhine in Germany) 857 A.D.: great plague of swollen blisters that consumed the people with loathsome rot, so that their limbs were sclerotia and loosened and fell before death. healthy grain. Ergot poisoning is a result of exposure to three groups of ergot alkaloids: ergotamines, ergobasines and ergotoxines. These three affect muscle control including the smooth muscles in the blood vessels and excite nervous system, especially parts of the midbrain. All this turns into a great combination of convulsions and hallucination. These toxins cause two groups of symptoms: gangreous and convulsive ergotism. The former results in constriction of blood vessels, in extremities in particular. The latter will cause whole body to go through violent and sudden convulsions. sclerotia and healthy grain. The convulsions combined with the blood vessel constriction and hallucinations have been related to being possessed by evil spirits. These symptoms are likely to relate to the inquisition and witch-burning as the popular medieval past time. THE EXORCIST may not have had anything to do with the 1973 horror movie. 4

5 A potential example of ergot symptoms and their outcomes may be the Salem witch trials (1692) - other hypotheses including the real possession by evil spirits do exist. The argument is that the climatic pattern at that time seemed favorable for ergot. Eight young girls were thrown into convulsive fits; in search of the culprits 19 women were found guilty of witchcraft and hung. sclerotia and healthy grain. Salem witch trials and the results of those trials Although lesser in importance in modern times, ergot is not only a historical problem although the last great epidemic might have been in 1880 s in France. In 1926 and 1927 there were 12,000 reported cases of convulsive ergotism in Russia; in people suffered from ergotism symptoms and 5 died in France. The ergot-related spontaneous abortions and loss of limbs still occur among livestock. sclerotia and healthy grain. Salem witch trials and the results of those trials 5

6 Ergot as medicine: Long history: first existing record - use of ergot to precipitate child birth in Germany This did not last, however, since use of ergot led to spasms and danger to the child. The practice was discontinued sometime in the 1900th century Use ergot alkaloids in childbirth was due to the properties resulting in blood vessel constriction, in addition to inducing childbirth this reduced the risk of internal bleeding. Albert Hofman (1930 s) Currently, ergot alkaloids are being explored for use in migraine treatment. Ergot products are available under CafErgot, Ergate, and Migril trade names. Ergot as medicine: As said, ergot contains a good mixture of alkaloids. The core of these alkaloids is lysergic acid. One of the derivatives - lysergic acid diethylamide is better known as LSD. LSD stimulates midbrain and has a serotonin blocking effects. Albert Hofman, an Austrian biochemist, discovered LSD by accident - he was feeling funny after a long-day in the lab. He assumed that his symptoms were due to absorption through skin. According to Albert Hofman, LSD produced symptoms which included dizziness, feeling of anxiety, visual distortions, symptoms of paralysis, and desire to laugh. Hofman explored the potential of LSD with his colleagues on so-called business trip. Albert Hofman (1930 s) 6

7 Ergot as medicine: LSD had the great promise to be a great psychoactive drug to reveal the past and forgotten event in the mental patients history. It also had potential for military intelligence use. For a brief while in 1950 s and 1960 s CIA was the main supplier of psychoactive drugs to the military and public during field trials of LSD. This resulted in legal charges against CIA as some of the unknowing and knowing test objects suffered from LSDinduced flashbacks or fatalities during the tests. Because of potential risks of anxiety and selfdestructive behavior in addition to general hazards to parties not involved in drug testing, recreational use of LSD is now considered illegal. Albert Hofman (1930 s) A look forward Perithecial ascomycetes with selected examples. Apothecial ascomycetes with selected examples. 7

8 Phylum Ascomycota - Perithecial ascomycetes Daldinia perithecium Inoperculate ascus with paraphyses Main characters Perithecia are embedded in a stroma Unitunicate, inoperculate asci Asci are persistent (not evanescent) Ascospores forcibly discharged (compare cleistothecia) Parasites, pathogens or symbionts of arthropods, endophytes of a variety of plants, mammalian and plant parasites and pathogens and finally lignocellulosic saprobes. Proposed relationships among the perithecial ascomycetes Phylum Ascomycota - Perithecial ascomycetes Epichloë on tall f escue leaves (Festuca rubra) Selected pyrenomycetes - Endophytic Hypocreales Endophytes (members of Hypocreales) of grasses. Like the Claviceps, produce toxic alkaloids. Some are systemic colonizers of range grasses, i.e., all plant tissues are colonized. The seeds are already colonized - following generations will also carry the endophytic colonization. The systemic colonizers are often very species specific. 8

9 Phylum Ascomycota - Perithecial ascomycetes Selected pyrenomycetes - Sporothrix schenkii Best know human pathogen of perithecial ascomycetes is Sporothrix schenkii. S. schenkii spores are soil-borne and cause lung infection via inhalation. More typically, S. schenkii will infect skin and adjacent lymphatic system. Due to the origin via skin punctures, this is also known as the rose-growers disease. Most common on skin and lymphatic system, but can disseminate to other parts of the body and infect bone joints. Sporothrix schenkii conidia Sporotrichosis on an Asian female Phylum Ascomycota - Perithecial ascomycetes Cordyceps myrmecophila on an ant Selected pyrenomycetes - Cordyceps Insect associate Cordyceps ssp. (Hypocreales). Typical Hypocrealean sporocarp with embedded perithecia. Cordyceps infects beetles and Lepidoptera and their larvae. Additional Hypocrealean necrotrophic parasites of spiders and arthropods (Torrubiella) and termites (Cordycepioideus). Colony of Torrubiella on an arthropod 9

10 Phylum Ascomycota - Perithecial ascomycetes Selected pyrenomycetes - Cryphonectria parasitica Cause of the devastating chestnut blight. It causes cankers and eventually death of the host due to the destruction of the vascular cambium. First recognized in NY zoological garden in By 1954, 3.6 million hectares - ca 8 million acres - were liberated from the former upper story dominant tree Castanea dentata - American chestnut. Losses on timber alone totaled $82.6 million in Bark cankers, wilting and resprouting below cankers. C. parasitica stroma on chestnut. Perithecia are borne within the stroma and release spores through the long osteolar necks. Discomycetes - the apothecial ascomycetes 10

11 Discomycetes - the apothecial ascomycetes More typical Aleuria aurentia apothecium Inverted cup apothecium of Leotia lubrica Sponge head - multiple joined apothecium of Morchella elata Phylum Ascomycota - Apothecial ascomycetes Things to know about an apothecium: hymenium, ascus, paraphyses. In perithecial, cleistothecial, or stromatal ascocarps we often would encounter pseudoparaphyses and periphyses Structure of a typical apothecium Hymenium in an apothecium; asci interspersed by paraphyses 11

12 Phylum Ascomycota - Apothecial ascomycetes Discomycetous lifestyles Saprobes on lignocellulosic substrates. Lichens. Mycorrhizal fungi. Disturbance-associated fungi (phoenicoid fungi). Plant parasites. Ascus operculum Phylum Ascomycota - Apothecial ascomycetes Selected examples - Monilinia fructicola Stone fruit (Monilinia fructicola Helotiales, Leotiaceae) Infects a variety of fruits. Determinate sclerotia. Compare Claviceps purpurea with overwintering sclerotia. Monilinia fructicola mummifying plums, cherries, apples, peaches and pears. Apothecia of Monilinia emerge from the mummified sclerotia. 12

13 Phylum Ascomycota - Apothecial ascomycetes Selected examples - Monilinia fructicola Monilinia fructicola on peaches Life cycle of Monilinia is characterized by prominent conidiophores on colonized fruit, and the resting sclerotia which give rise to the apothecial ascocarps. Summary Perithecial ascomycetes were characterized by persistent asci embedded in the ascocarp. Apothecial ascomycetes can have a great variation with inverted cups, joined apothecia, even enclosed apothecia. 13