Fungi

Chapter 31

Fungi

Fungi

Fungi

Fungi

More closely related to animals than plantsUnicellularMost are multi-cellularTropics to tundraAquatics to terrestrialAirborne sporesYeast in breads & beer

Fungi

Decomposers Recycle nutrientsHelp roots of plants absorb nutrientsDisease causing (plants and animals)Treatment difficult

Body structure

HyphaeTiny filamentsComposed of cytoplasmSurrounded by plasma membrane & cell wallCell wall made of chitinSeptaCross-walls that separate cells of hyphae

Hyphae

Fig. 31-3

(b) Coenocytic hypha

Septum

(a) Septate hypha

Pore

Nuclei

Nuclei Cell wallCell wall

Body structure

Mycelium:Mass of connected hyphae Surrounds & infiltrates material Maximizes contact with materialGrows rapidlyGrows underground so not visible

Reproduction

Each cell can have one or more nucleiMonokaryotic:One nucleiDikaryotic: Two haploid nuclei that function independently

Reproduction

Dikaryotic hyphaeHeterokaryotic:Nuclei that are from two genetically distinct individualsHomokaryotic:Nuclei are genetically similar

Reproduction

SexuallyAsexuallySpores are produced either waySpread by wind or on insectsSuitable environment give rise to new fungal mycelium

Reproduction

Sexual reproduction2 compatible mating types fuseUsually 2 haploid fuse to form diploidSome fungi remain 1n + 1n and not 2n+/- length of time

Reproduction

Plasmogamy:Fusion of cytoplasm of myceliaKaryogamy:Fusion of nuclei ZygotesMeiosisSpore formation

Reproduction

AsexuallyMoldsProduce haploid spores by mitosisYeastsMitosisBuds

Fig. 31-5-3

Spores

Spore-producingstructures

GERMINATION

ASEXUALREPRODUCTION

Mycelium

Key

Heterokaryotic(unfused nuclei fromdifferent parents)

Haploid (n)

Diploid (2n)

SEXUALREPRODUCTION

KARYOGAMY(fusion of nuclei)

PLASMOGAMY(fusion of cytoplasm)

Heterokaryoticstage

Zygote

Spores

GERMINATION

MEIOSIS

Fungi

HeterotrophsSecrete hydrolytic enzymes (exoenzymes)Absorb nutrients(organic molecules)

Nutrients

Digest wood (cellulose)Absorb the glucose Lignin (found in wood)Decomposer of living or dead organismsYield carbon, nitrogen and phosphorus

Nutrients

Obtain nutrients from tiny roundworms called nematodesParalyze Penetrate Absorb nutrients from bodyNitrogen source

Metabolic pathways

Anaerobic fermentationWines & cheesesSoy sauceAntibiotics & steroidsYeasts (single cell fungi)Bioremediation Using organisms to break up a toxin

Symbiosis

LichensFungus & photosynthetic partner (algae)Mutualism some are parasiticHyphae penetrate cell walls of algae Obtain nutrients from the algaeProtects the algae from too much sun

Symbiosis

Lichens first to invade a harsh environmentColored - pigments -protect the algae from the sunPigments are used as natural dyes

Lichen

Lichen

A fruticose (shrublike)lichen

A foliose (leaflike) lichen

Crustose (encrusting) lichens

Mycorrhizae

Tree (plant) roots with fungiFungi function as an extension of roots Plants absorb more nutrients, such as Zn, P, CuFungi gets organic materials from the plant

Mycorrhizae

1. Arbuscular:Fungal hyphae penetrate the trees rootsForm coils around rootsMore common2. Ectomycorrhizae:Hyphae do not penetrate the rootsHelps trees grow in infertile areas

Endophytes

Fungus lives inside the plantIntercellular spacesHelp defend plant against herbivores

Symbiotic relationship between fungi & ruminant animalsFungi helps digest the cellulose

Parasitic

MycosisFungal infectionRingwormAthlete’s footCandida albicans

Parasitic

Aspergillus Produces toxin harmful to humans.PneumocystisCauses a rare pneumonia in AIDS patientsChytridomycosisFungal infection that harms amphibiansOther fungal infections harm plantsChestnut trees, corn

Figure 31.UN07

Fungal Phylum Distinguishing Features

Chytridiomycota(chytrids)

Zygomycota(zygomycetes)

Glomeromycota(arbuscularmycorrhizal fungi)

Ascomycota(ascomycetes)

Basidiomycota(basidiomycetes)

Flagellated spores

Resistant zygosporangiumas sexual stage

Arbuscular mycorrhizaeformed with plants

Sexual spores (ascospores)borne internally in sacscalled asci; vast numbersof asexual spores (conidia)produced

Elaborate fruiting body(basidiocarp) containingmany basidia thatproduce sexual spores(basidiospores)

Fungi

Mycologists: scientists that study fungusFive groups1. Chytrids2. Zygomycetes3. Glomeromycetes4. Ascomycetes5. Basidiomycetes

1. Chytridiomycota (chytrids)

Aquatic fungi Flagellated spores called zoosporesDiverged earliest Chitin in the cell walls

2. Zygomycota

Bread moldsFruit moldsZygosporangium:Contains one or more diploid nucleiForms a hard coveringGood growth conditionsUndergoes meiosis then mitosisReleases spores

Zygomycota

Rhizopusgrowingon bread

SEXUALREPRODUCTION

Youngzygosporangium(heterokaryotic)

Gametangia withhaploid nucleiMating

type (–)

Matingtype (+)

Diploid (2n)

Haploid (n)Heterokaryotic (n + n)

PLASMOGAMY

Key

Diploidnuclei

Zygosporangium

100 µm

KARYOGAMY

MEIOSIS

Sporangium

Spores

Dispersal andgermination

ASEXUALREPRODUCTION

Dispersal andgermination

Sporangia

Mycelium50 µm

BREAD MOLD

Fig. 31-6

2.5 µm

3. Glomeromycetes

Arbuscular mycorrhizaeHyphae with plant rootsVery few species

4. Ascomycetes

Sac fungiMarine, freshwater & terrestrialYeastAsci: sac like structure containing sexual sporesAscocarps: contain asciFruiting bodiesMicroscopic or macroscopic

Ascomycota

Key

Haploid (n)

Diploid (2n)Dikaryotic (n + n)

Conidiophore

Mycelium

ASEXUALREPRODUCTION

Germination

Hypha PLASMOGAMY

Haploid spores (conidia)

Conidia;mating type (–)

Matingtype (+)

SEXUALREPRODUCTION

Dikaryotichyphae

Ascus(dikaryotic)

Mycelia

KARYOGAMY

Diploid nucleus(zygote)

Germination

Asci

Dispersal

Dispersal

AscocarpEightascospores

Fourhaploidnuclei MEIOSIS

YEAST

Figure 31.15

Morchellaesculenta

Tuber melanosporum

5. Blasidiomycetes

Mushrooms, shelf fungi, puff ballsBlasidium (Latin means “little pedestal”)Long-lived dikaryotic mycelium Leads to more genetic re-combinationsBlasidiocarps (mushroom) Produced sexuallyFruiting bodiesWood decomposers

Basidium

Blasidiomycetes

SEXUALREPRODUCTION

Diploid (2n)

Haploid (n)Dikaryotic (n +n)

Key

PLASMOGAMY

Matingtype (+)

Haploid myceliaDikaryotic mycelium

Matingtype (–)

Basidia(n+n)

Gills linedwith basidia

Basidiocarp(n+n)

KARYOGAMY

Diploidnuclei

MEIOSIS

Basidium containingfour haploid nuclei

Dispersal andgermination

Basidiospores(n)

Basidium withfour basidiospores

Basidiospore1 µm

Haploid mycelia

Figure 31.17c

Maiden veil fungus