In general terms, describe the importance of fungal associations with plants.
- live in close association with plants
- Mututalism - x change mycorrhizal associations b/t fungi and plant roods = faster growth of plants supply plants with key nutrients carbon, nitrogen & Phosphorus
- decompose dead wood (absorbe cellulose and lignin) = master recyclers of nutrients in terrestrial environments increasing productivity and bodiversity
How are fungi involved in nutrient cycling?
- release nutrients from dead plants and animals key recyclers of carbon, nitrogen, and phosphous
- = increase productivity and biodiversity
- mutualisim - sugars and CO2 for nutrients fro plant
What negative impacts do fungi have on the human food supply?
diseases in crop plants fruit spoilage epidemics in trees -> chestnuts and elms
Human: diaper rash, ringworm, vaginitis, non bactrial phnemonia
Identify Saccharomyces ceriviserae and several common ways humans use it.
bread yeast, beer, wine, cheese, tofu, whiskey
CO2 as a byproduct
Fungi are a poorly studied branch of the tree of life with about 80,000 species described. What is one estimate for the actual number of fungal species?
Identify and describe the two common growth forms that occur among the fungi.
- Single-celled forms—yeasts.
- Multicellular, filamentous forms—mycelia.
Discuss the characteristics of fungal hyphae and variation in septa.
- filaments that make up a mycelium are called hyphae.
- Each filament is separated into cell-like compartments by cross-walls called septa.
- Gaps in septa called pores enable materials to flow between compartments.
Discuss the diversity of reproductive structures in fungi spores
- spores resistant to drying out
- Both the sexually produced gametes
- the asexually produced spores in the chytrids have flagella - only known motile fungal cells.
Discuss the diversity of reproductive structures in fungi - swimming gametes
- flagella spores & gametes in wet environments
- only in Chytrids
Discuss the Discuss the diversity of reproductive structures in fungi - zygosporangia
The zygomycetes have zygosporangia, formed when cells from two yoked-together haploid hyphae fuse.
Discuss the diversity of reproductive structures in fungi d) basidia
Basidia are specialized spore-producing cells that form at the ends of basidiomycetes hyphae.
Discuss the diversity of reproductive structures in fungi e) asci
Asci are sac-like spore-producing cells that form at the end of ascomycetes hyphae.
Where do fungi appear on the phylogenetic tree of life? What morphological traits link fungi and animals?
- DNA sequence data.
- Both animals and fungi synthesize chitin.
- Chytrid and animal flagella are similar in structure and function.
- Both groups store glucose as glycogen.
Deciphering the phylogeny of the fungi is very much a work in progress. Which fungal groups are monophyletic and which are presently paraphyletic?
- The Chytridiomycota and Zygomycota are paraphyletic. A single common ancestor did not give rise to all species within each phylum.
- The Glomeromycota, a group of zygomycetes, is monophyletic. The Basidiomycota (club fungi) and Ascomycota (sac fungi) are monophyletic, and are the most highly derived groups of fungi.
The two groups are both dikaryotic and together form a monophyletic group.
Use experimental evidence to answer the question, “Are mycorrhizal fungi mutualistic?”
Experimental evidence indicates that mycorrhizal fungi and plants are mutualistic.
test via Carbon tagged air ( mychorrhizal in soil vs. without) - carbon moved through plant and was fed to the fungi
in soil tagged Phosphorus and Nitrogen
- went throught the fungi and found in the plant
Compare and contrast the two main types of mycorrhizal associations (EMF and AMF/VAM)
- EMF doesn't enter the root cells Basidiomycota and some ascomycetes, found in temperate regions
- AMF grow into the cells of root tissue and direct contact with the plasma membrane increasing SA found in glomeromycota, tropical habitat
Characterize fungal endophytes, and lichens, including possible benefits to the partners in these associations.
Endophytes in some grasses produce compounds that deter herbivores - some commensal releationships - not noticeable effect
toxic to plant eaters
but prevents plant from reproducting
Discuss extracellular digestion in the wood rot fungi including ‘enzymatic combustion’ in the degradation of lignin, as well as the role of cellulases.
Basidiomycetes can completely degrade both lignin and cellulose lignin peroxidase to get to cellulose via cellulases to form glucose
- extracellular digestion
- uncontrolled oxidation by lignin peroxidases - the oxidation of lignin cannot be harness to drive ATM prodution
- denegration of lignin gives access to cellulose and allows lignin peroxidases to expose cellulose
- exposed cellulos degrated by cellulases specifically transform stoage into glucose
Fungal reproduction is varied. a) Explain why in the fungi we generally do not see eggs and sperm but instead have mating types.
- Chytridiomycota produce gametes, and no fungus produces gametes that are different enough in size to be called sperm and egg. In many fungi, fertilization occurs in two steps, which can be separated in both time and space:
- Fusion of cells.
- Fusion of nuclei from the fused cells.
Fungal reproduction is varied. b) In most fungal groups, instead of fertilization, the concepts of plasmogamy and karyogamy are used instead. Explain.
- sexual reproduction begins when hyphae from two individuals fuse to form a hybrid hypha.
Plasmogamy occurs when the cytoplasms fuse. If the nuclei remain independent, the mycelium becomes heterokaryotic.
Karyogamy occurs when the nuclei fuse to form a diploid zygote.
How does the life cycle of Chytrids differ from the generalized fungal life cycle?
- Chytridiomycota are the only fungi that produce gametes and exhibit alternation of generations.
- Swimming gametes are produced by mitosis in haploid adults.
- Gametes fuse to form a diploid zygote, which grows into a sporophyte.
- Haploid spores, which disperse by swimming, are produced by meiosis inside the sporophyte’s sporangium.
List key features of Microsporidia Examples
- single celled
- parasitic with a polar tube
- reduced genome
- lack mitochondria
List key features of Chytrids Example
- not monophyletic aquatic - typically fershwater environment spores with flagellum
- can digest cellulose
- lifestyles range from decomposers to parasites to mutialists
List key features of Zygomycetes
- Zygomycota form yoked hyphae that produce a spore-forming structure.
- Soil dwellers
- Plasmogamy forms a zygosporangium that develops a tough, resistant coat. Inside the zygosporangium, nuclei from the mating partners fuse—meaning that karyogamy occurs many sprophytes
List key features of Glomeromycota
- AMF are all members of Glomeromycota
- spores develop underground
- difficult to grow in lab
- Very important to grasslands and tropical forests
List key features of Basidiomycota
- basidiomycete reproductive structures originate from the heterokaryotic hyphae of mated individuals
- Karyogamy occurs within the basidia.
- The diploid nucleus that results undergoes meiosis, and four haploid spores, which will eventually be ejected and dispersed by the wind,
- mature dikaryotic mycelia food sourses and boiolgical research
List key features of Ascomycota
- Ascomycota have reproductive structures, which are produced by dikaryotic hyphae, with many spore-producing asci.
- After karyogamy occurs inside each ascus, meiosis takes place and haploid spores are produced.
- When the ascus matures, the spores inside are forcibly ejected and then dispersed by the wind.
- two major groups: lichen formers and non-lichen formers
Which key features match to the appropriate lineage of fungi Have a dikaryotic stage; basidium is the site of meiosis – producing four spores; basidia often borne in large, above ground reproductive structures; some are ectomychorrhizal
Which key features match to the appropriate lineage of fungi Single-celled intracellular parasites; infection by polar tube which penetrates the membrane of the host cell; highly reduced genome; lack functioning mitochondria
Which key features match to the appropriate lineage of fungi Have a dikaryotic stage; ascus is the site of meiosis – producing eight ascospores; many are lichen-formers; some prey on microscopic animals and protists
Which key features match to the appropriate lineage of fungi Common saprophytes and parasites in freshwater and wet soils; flagellated spores and gametes with a single flagellum; mutualists in the guts of ruminant animals
Which key features match to the appropriate lineage of fungi Hyphae of differing mating types fuse to form a zygosporangium where nuclear fusion, then meiosis occurs; common in soil; asexual reproduction extremely common
Which key features match to the appropriate lineage of fungi
Which key features match to the appropriate lineage of fungi The only group that form arbuscular mycorrhizae (AMF); hyphae lack cross walls; produce large underground asexual spores; no sex evident
Which class of taxa of do these fungi belong? Cup fungi, truffles, lichens, morels, yeasts (ex. Saccharomyces, Candida); Penicillium; nematophagus fungus Dreschslerella
Which class of taxa of do these fungi belong? Arbuscular mycorrhizal fungi Glomus, Gigaspora
Which class of taxa of do these fungi belong? Mushrooms (ex. Agaricus), boletes, brackets, earthstars, puffballs, stinkhorns, bird-nest fungi, coral fungi, rusts, smuts
Which class of taxa of do these fungi belong? Include common moulds Rhizopus, Mucor; coprophilic fungi Pilobolus, Spiromyces
Which class of taxa of do these fungi belong? Parasites of insects and vertebrates, Nosema tractabile
Which class of taxa of do these fungi belong? Batrachochytrium causes chytridiomycosis in amphibians; Spizellomyces are anaerobic gut fungi in ruminants
Fungi secrete enzymes so that digestion takes place outside their cells. Their morphology provides a large amount of surface area for efficient absorption.
____________ occurs when the nuclei fuse to form a diploid zygote.
sexual reproduction begins when hyphae from two individuals fuse to form a hybrid hypha. ____________ occurs when the cytoplasms fuse.
Many lichens reproduce asexually via the production of small “mini-lichen” structures called _________ that contain both symbionts