20 - Fungal Diversity

Final

how do fungi propogate themselves?

By producing spores sexually or asexually

how do spores disperse?

through wind or water where if they land in a moist place, they will germinate

What is the cycle of asexual reproduction?

spores, germination, mycelium, and spore-producing structures

• reproduction occurs through simple cell division or pinching of small “bud cells” off a parent cell

How does sexual reproduction of fungi work?

It requires plasmogamy (fusion of cytoplasm), then the heterokaryotic stage, and karyogamy (fusion of nuclei)

what is a heterokaryon?

a mycelium that contains coexisting genetically different nuclei

What happens after keryogamy?

when the haploid nuclei fuse, a diploid cell is produced (zygote), it undergoes meiosis where spores and produced and germinated to produce mycelium.

sexual reproduction produces…

genetic variation

How were the five phyla of fungi produced

they were established according to their mode of sexual reproduction

1. chytrids

2. zoopagomycetes

3. mucoromycetes

4. ascomycetes

5. basidiomycetes

What does the sixth basal group contain

two phyla that reproduce without a sexual cycle - cryptomycetes and basidiomycetes

what are the characteristics of cryptomycetes

• found in soils, marine, and freshwater habitats

• unicellular and flagellated spores

• members from the rozella parasitize protists and other fungi

microsporidians - basal

• unicellular intracellular parasites of protists and animals

• highly reduced mitochondria and small genomes

• produce spores that infect host cells via polar tubule (harpoon-like organelle)

true - chytrdiomycota

• simplest and most primitive true fungi

• ecological habitat (mostly aquatic) and cell structure share commonality w protists

• nearly all have zoospores

true - zoopagomycota

• 900 known species

• form coenocytic hyphae and reproduce asexually via non-flagellated spores

• those that reproduce sexually form a zygosporangium (houses and protects zygote)

how is zygosporangium formed

fusion between mycelia of different mating types

Zoopagomycota/Mucuromycota Plasmogamy

• maitng type mycelia meet and fuse

• after plasmogamy, cells undergo karyogamy where two nuclei fuse and undergo meisosis to produce spores

zygosporangia

metabolically inactive and resistant to freezing and drying

• improved conditions leads to meiosis where zygosporangium germinates into sporangium

• sporangium develops at the tips of the upright hyphae and functions to release spores

true- ascomycota

• form septate hyphae with pores

• vary in size and complexity from unicellular yeasts to elaborate cup fungi and subterranean morels

why are ascomycetes called sac fungi

because of their saclike asci, where spores are produced

• during the sexual stage, ascomycetes produce ascocarps which contain the spore forming asci

process of ascomycete asexual reproduction

• reproduce by enormous numbers of conidia (asexual spores produced at the tips of conidiophores)

ascomycete sexual reproduction

• mycelium from diff mating types fuse

• dikaryotic cells formed containing two haploid nuclei, one from each parent

• asci form at the tips of dikaryotic hyphae and karyogamy + meiosis occur within asci

• ascospores develop and are discharged from the ascocarp

true- basiciomycota

• defined by a clublike structure called a basidium (where karyogamy and meiosis occur)

• phylum includes mushrooms, puffballs, and shelf fungi

• life cycle usually involves long-lived dikaryotic mycelium

life cycle of a basidiomycete

• includes a dikaryotic mycelium

• mycelium can reproduce sexually by producing basidiocarps (fruiting bodies)

What are the different fungal ecological roles?

• saprotrophic (decay)

• parasitic (fungi absorb nutrients)

• mutualistic (absorb nutrients but also reciprocate that benefit host)

How do Fungi act as decomposers?

they are efficient at decomposing organic material like cellulose and lignin (plant material)

what are endophytes?

• fungi that live inside leaves or other plant parts without causing harm

• all plant species harbor symbiotic endophytes

• most endophytes are ascomycetes

• some make toxins to defend host plant, others help with heat, drought, or heavy metals

what is an example of a fungal-animal mutualism

• some fungi share digestive services w animals

• help break down plant material in gut

• eg. ants provide leaves to fungi that provide them with food from hyphae

what are lichens

symbiotic associations between photosynthetic microorganisms and fungi that grow on the surfaces of rocks, rotting, logs, trees, and roots in various forms

how do lichens reproduce?

• asexually by fragmentations or by formation of soredia (small clusters of hyphae with embedded algae)

• fungal partner of many lichens can reproduce sexually

How can fungi be harmful?

• about 30% of fungi species are parasites or pathogens on or in plants which results to a 10 - 50 percent loss in harvest every year

• two chytrid species have been implicated in the decline or extinction of 500 different amphibian species

• can cause severe skin infections leading to massive die offs

how does the disease cytridiomycocis affect amphibian species?

• a fatal skin disease caused by chytrid fungal pathogens

• death of amphibians result from inability to regulate water through skin

practical uses of fungi

• fungi for food and making cheese hehhehe

• alcohol

• and soy sauce ay