Fungi

1. Fungi Barbara Musolf Clayton State University A&S Building G 110-G 678-466-4851

2. Objectives What are fungi characteristics? How do fungi reproduce? What are the origins of fungi? Fungi phylogeny What are the roles that fungi play in our lives?

3. Fungi facts Fungi are huge and often aged organisms. Fungi in Oregon is ~ 2,200 acres, weighs hundreds of tons, and is 2,600 years old. Fungi are a diverse group of organisms�1.5 million species ranging from single to multicellular forms. Inhabit every ecological niche including air, 160 km above ground. Plants depend on a symbiotic relationship to fungi We depend on them to make bread and beer. A tiny fraction produce diseases in plants and animals Fungi helps roots absorb minerals from the soil.Fungi helps roots absorb minerals from the soil.

4. Fungal nutrition Fungi are heterotrophs Digest food by releasing hydrolytic enzymes called exoenzymes. Saprobes digest nonliving organic material Parasitic fungi absorb nutrients from living hosts Pathogenic parasites Mutualistic fungi absorb nutrients from plants and in return helps plants absorb minerals from the soil. Predatory fungi sticky substances secreted by hyphae trap organisms that are then invaded by hyphae Hyphae form nooses that swell and trap organisms Most patients who die of AIDS die of the funcal diseases Pneumocystis carinii and Candida albicans. They also cause ringworm and athletes foot. Fungi are the most damaging plant pathogensMost patients who die of AIDS die of the funcal diseases Pneumocystis carinii and Candida albicans. They also cause ringworm and athletes foot. Fungi are the most damaging plant pathogens

5. Fungi body structure Single cell fungi are known as yeasts. Multicellular fungi Hyphae are composed of tubular cell walls of chitin surrounding the plasma membrane and cytoplasm Mycelia are a mass of hyphae that surrounds the organisms on which the fungi feed. It produces a large surface area for absorption (1km in length found in 1cm3). A mycelium can grow rapidly as proteins used for assembly of the mycelium move through the mycelium via cytoplasmic streaming to the tips of the hyphae. Rapid growth compensates for the fungi inability to move.Hyphae are composed of tubular cell walls of chitin surrounding the plasma membrane and cytoplasm Mycelia are a mass of hyphae that surrounds the organisms on which the fungi feed. It produces a large surface area for absorption (1km in length found in 1cm3). A mycelium can grow rapidly as proteins used for assembly of the mycelium move through the mycelium via cytoplasmic streaming to the tips of the hyphae. Rapid growth compensates for the fungi inability to move.

6. Structure of hyphae Septate hyphae�cells are divided by septa that have pores Mitochondria, ribosomes and nuclei can travel from cell to cell Coenocytic hyphae�continuous cytoplasmic mass with multiple nuclei Coenocytic hyphae are produced by mitosis without cytokinesis (similar to slime molds)Coenocytic hyphae are produced by mitosis without cytokinesis (similar to slime molds)

7. Specialized hyphae Hyphae are modified to form hoops that can constrict a nematode < sec and then hyphae penetrate and digest the tissues.

8. Haustoria Mycorrhizae penetrate plant roots and deliver phosphate and minerals in exchange for organic nutrients. Ectomycorrhizal Endomycorrhizal Ectomycorrhizal fungi form sheaths of hyphae on the outside of the root and grow into the extracellular spaces of the cortex Endomycorrhizal fungi penetrate the cell wall into tubes formed by the root cell membrane.Ectomycorrhizal fungi form sheaths of hyphae on the outside of the root and grow into the extracellular spaces of the cortex Endomycorrhizal fungi penetrate the cell wall into tubes formed by the root cell membrane.

9. Generalized fungi life cycle Propagate through production of spores that travel by air Nuclei of pores and hyphae haploid except during a brief transitional state. Sexual reproduction is initiated through release of pheromones that bind to receptors and cause growth of hyphae towards the pheromone releasing hyphae. Fusion occurs. The fusion of the cytoplasm of two parents is plasmogamy, however the nuclei are not fused at this time and they remain in an heterokaryotic state with nuclei with different genetic content. In some species heterokaryotic mycelia become mosiacs Some mingle and may exchange chromosomes and genes. Some have two different nuclei pair up and are dikaryotic. The nuclei can undergo cell division in each cell without fusing Karyogamy is the fusion of the two parent nuclei to form a diploid cell. Meiosis restores the haploid condition and the mycelium produces specialized reproductive structures that produce the spores.Nuclei of pores and hyphae haploid except during a brief transitional state. Sexual reproduction is initiated through release of pheromones that bind to receptors and cause growth of hyphae towards the pheromone releasing hyphae. Fusion occurs. The fusion of the cytoplasm of two parents is plasmogamy, however the nuclei are not fused at this time and they remain in an heterokaryotic state with nuclei with different genetic content. In some species heterokaryotic mycelia become mosiacs Some mingle and may exchange chromosomes and genes. Some have two different nuclei pair up and are dikaryotic. The nuclei can undergo cell division in each cell without fusing Karyogamy is the fusion of the two parent nuclei to form a diploid cell. Meiosis restores the haploid condition and the mycelium produces specialized reproductive structures that produce the spores.

10. Generalized fungi life cycle

11. Generalized fungi life cycle Clones are produced by mitotic production of spores which are distributed by air or water. Molds and yeasts commonly reproduces asexually. Clones are produced by mitotic production of spores which are distributed by air or water. Molds and yeasts commonly reproduces asexually.

12. Reproduction in molds and yeasts Yeast cells bud off of parent cells. Some yeasts produce filamentous mycelia. Molds and yeasts are referred to as deuteromycetes because they are �imperfect�; they do not sexually reproduce.Yeast cells bud off of parent cells. Some yeasts produce filamentous mycelia. Molds and yeasts are referred to as deuteromycetes because they are �imperfect�; they do not sexually reproduce.

13. Evolution of fungi Evolved from flagellated unicellular ancestor A member of the opisthokont clade (animals, fungi and protistan relatives). Ancestors of animals and fungi diverged 1.5 billion years ago Fossil evidence is from 460 million years ago. Opisthokont refers to the location of the flagellum (posterior) Multicellularity was evolved independently in fungi and animalsOpisthokont refers to the location of the flagellum (posterior) Multicellularity was evolved independently in fungi and animals

14. Fungi phylogeny Dashed lines indicate groups thought to be paraphyletic, traced to presence or loss of flagellum.Dashed lines indicate groups thought to be paraphyletic, traced to presence or loss of flagellum.

15. Chytrids Found in lakes, soil, and marine environments Saprobes and parasites Parasites of protists, plants or animals Have flagellated spores called zoospores

16. Zygomycetes Fast growing and diverse Rot agricultural food products Parasites or commensal symbionts of animals Hyphae are coenocytic and only form septa where reproductive cells are formed. Asexual reproduction during plenty and sexual reproduction in response to deteriorating environment. Zygosporangia are resistant to freezing and drying

17. Zygomycetes Microsporidia are unicellular parasites of animals and protists. Parasitic lifestyle led to reduced and tiny organelles.

18. Zygomycetes Pilobolus has a novel way to find animal dung to decompose�get eaten Pilobolus faces the light and releases spores that can travel up to 2 m. The goal is to spew the spores onto grass that grazing herbivorous animals can eat. Once they are in the digestive tract they can survive until the food is processed down to the dung.Pilobolus faces the light and releases spores that can travel up to 2 m. The goal is to spew the spores onto grass that grazing herbivorous animals can eat. Once they are in the digestive tract they can survive until the food is processed down to the dung.

19. Glomeromycetes All are arbuscular mycorrhizae Form a symbiotic relationship with 90% of plants by pushing into the root cells and forming branchlike structures called arbuscules by pushing into the root cells and forming branchlike structures called arbuscules

20. Ascomycetes (sac fungi) Live in a variety of marine, freshwater and terrestrial habitats Produce sexual spores in saclike asci Asexual reproduction though release of conidia from conidiophores 40% live in symbiotic relationship with green algae or cyanobacteria as lichens. Neurospora crassa (bread mold) is a model organism in genetic studies�has a mechanism to prevent buildup of junk DNA Conidiophores are formed from the tips of specialized hyphae that tend to form clusters or long chains Used to formulate one gene, one enzyme hypothesis. The genome has been sequenced and it has 10,000 genes Neurospora crassa has been used to study circadian rhythms. Conidiophores are formed from the tips of specialized hyphae that tend to form clusters or long chains Used to formulate one gene, one enzyme hypothesis. The genome has been sequenced and it has 10,000 genes Neurospora crassa has been used to study circadian rhythms.

21. Ascomycetes (sac fungi)

22. Basidomycetes (club fungus) Named for the basidium, the cell in which the transient diploid stage occurs. The club-like shape of the basidium led to the common name of club fungus The basidiocarp is the fruiting body that we know as the mushroom. Saprobic basidiomycetes are very effective at decomposing lignin.

23. BasidomycetesLife cycle Have a long-lived dikaryotic mycelium The basidiocarp is sexually reproduced and erected in a few hours.

24. Basidomycetes Life cycle The mycelium below the �fairy ring� expands 30cm per year. The myecelium can be centuries old. A common mushroom can release billions of spores Asexual reproduction is less common

25. Fungal ecological relationships Decomposers�decompose cellulose and lignin and almost any carbon based compound. Returns inorganic substances to the soil

26. Fungal ecological relationships Symbionts�with plants, algae, cyanobacteria and animals Mycorrhizae provide essential nutrients for plants Help digest plant material in animal guts. Ants farm fungi Ants (leaf cutting ants)provide food for the fungi�gather it and the fungi breaks down the plant cellulose into a form that they can digest an live onAnts (leaf cutting ants)provide food for the fungi�gather it and the fungi breaks down the plant cellulose into a form that they can digest an live on

27. Lichen Lichen form symbiotic relationship with photosynthetic microorganisms Photosynthetic partner is usually cyanobacteria or green algae Provides carbon compound and fixes nitrogen Fungal partner is usually an ascomycete, although some basidomycetes form lichen Provides protection, minerals, water and gas exchange Lichens reproduce sexually by forming ascocarps or basidocarps

28. Lichen Fruticose Foliose Crustose

29. Fungal pathogens About 30% of fungi are parasites Dutch Elm disease was caused by an ascomycete 10-50% of fruit harvest is lost to fungus Aspergillis found on grains and peanuts produces aflatoxin, a carcinogen Mycosis�fungal infections Ringworm Systemic infections such as Candida albicans and Coccodoidomycosis, which produces TB like symptoms in lungs Stachybotrys chartarum, an ascomycete responsible for �sick buildings� Claviceps purpurea forms purple structures called ergots on rye, which is a toxin that can cause gangrene, nervous spasm, burning sensations, hallucinations, and termporary insanity. One of the compounds found in this toxin is LSD.Claviceps purpurea forms purple structures called ergots on rye, which is a toxin that can cause gangrene, nervous spasm, burning sensations, hallucinations, and termporary insanity. One of the compounds found in this toxin is LSD.

30. Fungal benefits Food Mushrooms, truffles, morels Used in producing cheese, beer (Saccharomyces cerevisiae), bread Medicine Antibiotics�Penicillium Blood pressure medication from ergots Genetically engineered to produce insulin Used as model organisms to study genetics of eukaryotes Mushrooms are a good source of fiber and provide vitamins such as thiamine (B1), riboflavin (B2), niacin (B3), biotin (B7), cobalamins (B12) and ascorbic acid (C), as well as minerals, including iron, selenium, potassium and phosphorus. Mushrooms have been gaining a higher profile for containing antioxidants Ergothioneine and Selenium. Mushrooms are a good source of fiber and provide vitamins such as thiamine (B1), riboflavin (B2), niacin (B3), biotin (B7), cobalamins (B12) and ascorbic acid (C), as well as minerals, including iron, selenium, potassium and phosphorus. Mushrooms have been gaining a higher profile for containing antioxidants Ergothioneine and Selenium.