Chapter 21 Mrs. LaLone. Kingdom Fungi Mycologists study fungus! Eukaryotic Organisms Ex: Mushrooms,...

Kingdom FungiChapter 21

Mrs. LaLone

Kingdom FungiMycologists study fungus!Eukaryotic Organisms

Ex: Mushrooms, yeasts, molds70,000+ species of FungusMostly TerrestrialForm spores at some stage of lifecycleHave a Cell Wall

Composed of chitin – Nitrogen based polysaccharide

Resistant to breakdown by microorganismsMore resistant than cellulose

NutritionAll are Heterotrophic

Most are saprophytic – feed on the remains of dead organisms “decomposers” Fungi secrete enzymes that initiate digestion

outside the hypha Then absorb nutrients through the plasma

membranes of their cellsSome are parasitic – obtain nutrients from

living organisms; ex: plant pests

ClimateGrow best in moist environments

Produce spores in dry environments (resting stage)

Optimum pH is slilghtly acidic ~5.6 Range from 2-9

Wide temperature range

Body PlansUnicellular: YeastsMulticellullar: filamentous molds

MildewsWheat rustCorn smutMushroomsOther fungi

Body PlansFilamentous molds

Mold – consists of long, branched threads (filaments) “hyphae” Form a tangled mass/tissue “mycellium” Some coenocytic – large, multinucleated mass Some have septa – cross-walls with pores

Dikaryotic – contain 2 genetically distinct nuclei Monokaryotic – contain only one nucleus See Figure 21-1

Fig. 21-1, p. 407

FungusHave 2 distinct stages

Vegetative stage Often goes unnoticed

Conspicuous Reproductive stage The familiar form that people notice

Mushrooms, puffballs, bracket fungi

ReproductionSexual

Fruiting bodies (the familiar forms of fungi) Ex: mushroom top

Plasmogamy 2 different hyphae come together and cytoplasm

fuses 2 haploid nuclei fuse (karyogamy) Results in diploid zygote nucleus Meiosis occurs; producing haploid spores

ReproductionAsexual

FissionBuddingSpore Formation

Spores – nonmotile reproductive cells (wind & animals)

Produce on aerial hyphae Allows air currents to disperse cells

ClassificationBased on:

Characteristics of sexual sporesCharacteristics of fruiting bodiesDNA & RNA sequences

Kingdom Fungi5 Phyla

Phylum Chytridiomycota (Chytrids)Phylum Zygomycota (Sporangium Fungi)Phylum Glomeromycota (Mycorrhizae)Phylum Ascomycota (Sac Fungi)Phylum Basidiomycota (Club Fungi)

Phylum Chitridiomycota: ChytridsFungus that produce flagellated cells at some

stage in its lifeInhabit ponds, damp soil, & some in saltwaterMost are decomposers, some cause diseases

in plants and animalsMost unicellular or few cells that compose a

thallus a simple body that lacks roots, stems, or leaves &

rhizoids anchor/root-like

Phylum ZygomycotaBlack Bread MoldProduce zygosporesCoenocytic hyphaeSee figure 21-6

Fig. 21-6, p. 410

Zygomycetes

Phylum GlomeromycotaMycorrhizae – “Fungus Roots” a symbiotic

association between fungus and plant rootThe roots supply the fungus with sugars,

aminoacids, and other organic substancesThe mycorrhizal fungus benefits the plant by

extending the reach of its roots helps plant take in more water and minerals

Coenocytic (no septa) hyphae Asexual – blastospore (multinucleate

spores)

Fig. 21-8, p. 412

Glomeromycetes

Fig. 21-15a, p. 419

Fig. 21-15b, p. 419

Phylum AscomycotaSac Fungi

Their spores are produced in little sacs called asciHyphae usually have perforated septa

Cytoplasm and nuclei can move from one cell to another

Examples: Powdery mildews (cause food to spoil)Cup fungiEdible morels and trufflesYeastsDiseases caused: Dutch elm disease, chestnut blight, ergot

disease on rye, mildew on fruitsNonmotileSexual – ascospores (ascocarp=fruiting body)Asexual – spores called conidia

Fig. 21-11a, p. 415

Ascomycetes

Phylum Basidomycota“Club Fungi”Mushrooms, bracket fungi, puffballsParasites – wheat rust & corn smutDevelop basidium & basidiosporesMasses of hyphae form buttons

Each button forms a mushroom = stalk + cap Called a “basidiocarp” Have gills on lower surface of cap

Fig. 21-12, p. 416

Fig. 21-13, p. 417

Phylum Basidomycota

Ecological ImportanceDecomposeRelease CO2 to PlantsWithout fungus, minerals would be locked up

in dead organic matter; life would cease

Ecological ImportanceSymbiotic relationships

Animals (ex: cattle) cannot digest cellulose and lignin by themselves Fungi in gut do this

Mycorrhizae and plant rootsLichens – symbiotic relationships between

fungus + photosynthetic organism Ex: green alga or a cyanobacterium + ascomycete

fungus

Fig. 21-16, p. 420

Lichens

Lichens3 Growth Forms

Crustose – flat and grow tightly attached to rock

Foliose – Flat, leaflike lobes, not as tightly attached

Fruticose – Grow erect, branched/shrublike

LichensTolerate extremes of temperature and

moistureDo not grow in heavily polluted cities

Fungi are used to produceBeer – yeasts ferment grain (barley)Bread – yeast produce carbondioxide, and alcohol

(evaporates during baking)Cheeses Wine – yeast ferments fruit sugars to become ethyl alchololPenicillin – produced by a mold200 species of edible mushrooms70 poisonous

No easy way to distinguishSome have similar chemicals as LSD – trancelike state and

colorful visionsUsed for insecticidesPrevent spreading of malaria

Fungal DiseasesSuperfical infections (only infect skin, hair, or nails)

RingwormAthlete’s footJock itch

Candidiasis – yeast infection of mouth, throat, and vaginaOpportunistic fungi (occur when immune system is

compromised)Histoplasmosis – infection of lungs caused by inhaling

the spores of a fungus abundant in bird droppingsLiver damage and cancer

Caused by mycotoxins commonly grow on peanuts, pecans, corn, and other grains