fungi lecture 2013

Lecture: FungiLecture: Fungi

20132013

Strange but True: The Largest Organism Strange but True: The Largest Organism on Earth Is a Funguson Earth Is a Fungus

…….a relative out west that occupies some 2,384 acres (965 .a relative out west that occupies some 2,384 acres (965 hectares) of soil in Oregon's Blue Mountains. Put another way, this hectares) of soil in Oregon's Blue Mountains. Put another way, this humongous fungus would encompass 1,665 football fields, or nearly humongous fungus would encompass 1,665 football fields, or nearly four square miles (10 square kilometers) of turf.four square miles (10 square kilometers) of turf.

HIDDEN GIANT:HIDDEN GIANT: A small outcropping A small outcropping of honey mushrooms on the surfaceof honey mushrooms on the surface hide the largest known organism onhide the largest known organism on Earth, a fungus infesting the woodsEarth, a fungus infesting the woods of eastern Oregon.of eastern Oregon. Image: USDA FOREST SERVICE,Image: USDA FOREST SERVICE, PACIFIC NORTHWEST RESEARCH STATIONPACIFIC NORTHWEST RESEARCH STATION

http://www.scientificamerican.com/article.cfm?id=strange-but-true-largest-organism-is-fungus

Lichen – a vegetative body in which a Lichen – a vegetative body in which a fungus and one or more photosynthetic fungus and one or more photosynthetic organisms live together in mutual organisms live together in mutual dependency (mutualism)dependency (mutualism)

Metabolic products and remains enrich Metabolic products and remains enrich nutrient-poor soilnutrient-poor soil

Impacts, Issues: Impacts, Issues: Food, Forests, Food, Forests, and Fungiand Fungi

Lichens are sensitive to pollution and are Lichens are sensitive to pollution and are on the declineon the decline

Act as useful indicators of deteriorating Act as useful indicators of deteriorating environmental conditionsenvironmental conditions

Impacts, Issues: Impacts, Issues: Food, Forests, Food, Forests, and Fungiand Fungi

Fig. 24-1a, p.390

Food, Forests, and FungiFood, Forests, and Fungi

Fig. 24-1b, p.390


p.391


Reindeer mainly eat lichens in winter, especially reindeer moss.

LichenLichen

Combination of fungus and Combination of fungus and photosynthetic organism(s)photosynthetic organism(s)

Organisms are symbiontsOrganisms are symbionts

Relationship is a mutualismRelationship is a mutualism

Ecological Roles of LichensEcological Roles of Lichens

Survive in hostile habitats and colonize Survive in hostile habitats and colonize

new habitatsnew habitats

Absorb mineral ions from substratesAbsorb mineral ions from substrates

Cyanobacteria-containing lichens can fix Cyanobacteria-containing lichens can fix

nitrogennitrogen

Convert atmospheric nitrogen to a form Convert atmospheric nitrogen to a form

plants can useplants can use

Early Warning SystemsEarly Warning Systems

Lichens are very sensitive to deteriorating Lichens are very sensitive to deteriorating environmental conditionsenvironmental conditions

Absorb toxins but cannot get rid of themAbsorb toxins but cannot get rid of them

Can serve as environmental indicatorsCan serve as environmental indicators

MycorrhizaMycorrhiza

““Fungus-root”Fungus-root” Mutualism between a fungus and a tree Mutualism between a fungus and a tree

rootroot Fungus gets sugars from plantFungus gets sugars from plant Plant gets minerals from fungusPlant gets minerals from fungus Many plants do not grow well without Many plants do not grow well without

mycorrhizaemycorrhizae

Photo MicrographPhoto Micrograph

“Ectomycorrhizas. This group of mycorrhiza occurs mainly on roots of woody plants and only occasionally on herbaceous and graminaceous perennial plants. Some temperate tree species like beech, oak, spruce and pine cannot survive without ectomycorrhiza” http://soil-environment.blogspot.com/2010/08/role-of-mycorrhiza-in-mineral-nutrition.html

TrufflesTruffles

http://slowfoodwaltz.blogspot.com/2009/01/wonderful-world-of-truffles-why-truffle.html

**In Italy, a truffle dog is taught to retrieve a ball, then Gorgonzola cheese. Then the cheese is hidden and the dog has to sniff it out. It then get's rewarded for doing so. Finally, a small truffle is substituted for the cheese- you get the picture.

http://www.youtube.com/watch?v=GOJEv4JblHw

Truffle Hunting in Tuscany

Fungi as DecomposersFungi as Decomposers

Break down organic compounds in their Break down organic compounds in their surroundingssurroundings

Carry out extracellular digestion and Carry out extracellular digestion and absorptionabsorption

Plants benefit because some carbon and Plants benefit because some carbon and nutrients are releasednutrients are released

A Variety of RolesA Variety of Roles

Pathogens Pathogens

Spoilers of food suppliesSpoilers of food supplies

Used to manufactureUsed to manufacture AntibioticsAntibiotics

CheesesCheeses

Fungi Are HeterotrophsFungi Are Heterotrophs

Cannot carry out photosynthesisCannot carry out photosynthesis Must acquire organic molecules from the Must acquire organic molecules from the

environmentenvironment Most are saprobesMost are saprobes

Get nutrients from nonliving organic Get nutrients from nonliving organic mattermatter

Some are parasitesSome are parasites Extract nutrients from a living hostExtract nutrients from a living host

The MyceliumThe Mycelium

Most fungi produce a multicellular Most fungi produce a multicellular

feeding structure called a myceliumfeeding structure called a mycelium

It consists of branching tubular It consists of branching tubular

cells called hyphaecells called hyphae

Cell walls contain chitinCell walls contain chitin

p.392

one cell (partof one hypha ofthe mycelium)

The MyceliumThe Mycelium

Extracellular DigestionExtracellular Digestion

Mycelium grows into food sourceMycelium grows into food source

Tips of hyphae secrete digestive enzymesTips of hyphae secrete digestive enzymes

Enzymes break down organic material into Enzymes break down organic material into

simple forms that can be absorbed by simple forms that can be absorbed by

hyphaehyphae

Fungal Life CycleFungal Life Cycle

No motile stageNo motile stage

Asexual and sexual spores producedAsexual and sexual spores produced

Spores germinate after dispersalSpores germinate after dispersal

In multicelled species, spores give rise to In multicelled species, spores give rise to

a new mycelium a new mycelium

Fungal ClassificationFungal Classification

Fungi known from 900 myaFungi known from 900 mya 56,000 known species56,000 known species Three major lineages:Three major lineages:

ZygomycotaZygomycota Ascomycota (sac fungi)Ascomycota (sac fungi) Basidiomycota (club fungi)Basidiomycota (club fungi)

Imperfect fungi are those not yet Imperfect fungi are those not yet classifiedclassified

Fig. 24-2, p.392

zygomycetes sac fungi club fungi

chytridsmicrosporidians

amoeboid ancestors

FUNGI


Fig. 24-3a, p.392


Fig. 24-3b, p.392


Diversity of Club FungiDiversity of Club Fungi

25,000 species25,000 species MushroomsMushrooms Shelf fungiShelf fungi Coral fungiCoral fungi StinkhornsStinkhorns PuffballsPuffballs

Fig. 24-3c, p.392

Diversity of Diversity of Club FungiClub Fungi

Fig. 24-3d, p.392

Diversity of Diversity of Club FungiClub Fungi

Fig. 24-3e, p.392

Diversity of Club FungiDiversity of Club Fungi

Fungal SporesFungal Spores

Made up of one or a few cellsMade up of one or a few cells Can resist dehydrationCan resist dehydration Remain dormant until environmental Remain dormant until environmental

conditions favor germinationconditions favor germination Produced asexually or sexuallyProduced asexually or sexually Fungal classification is based on Fungal classification is based on

type of sexual sporestype of sexual spores

Fig. 24-4a, p.393

Fungal SporesFungal Spores

Blood Samples Show Deadly Blood Samples Show Deadly Frog Fungus at Work in the WildFrog Fungus at Work in the Wild

“High levels of an aquatic, chytrid fungus called Batrachochytrium dendrobatidis (Bd) disrupt fluid and electrolyte balance in wild frogs, the scientists say, severely depleting the frogs' sodium and potassium levels and causing cardiac arrest and death.” http://www.nsf.gov/news/news_summ.jsp?cntn_id=123871

Fig. 24-4b, p.393

skin surface Fungal Fungal SporesSpores

Types of Sexual SporesTypes of Sexual Spores

Club fungi make basidiospores on the Club fungi make basidiospores on the surface of a club-shaped cell (basidium)surface of a club-shaped cell (basidium)

Sac fungi produce ascospores inside a Sac fungi produce ascospores inside a parent cell called an ascusparent cell called an ascus

Zygomycete hyphae fuse to produce a Zygomycete hyphae fuse to produce a thick-walled zygospore thick-walled zygospore

Imperfect FungiImperfect Fungi

Species have never been observed to Species have never been observed to form sexual sporesform sexual spores

Many do make asexual sporesMany do make asexual spores

Predatory fungus Predatory fungus Arthrobtrys dactyloidesArthrobtrys dactyloides captures prey in nooselike hyphaecaptures prey in nooselike hyphae

Fig. 24-5, p.393

roundworm

part of a hypha that formed a nooselike ring around the worm

Imperfect FungiImperfect Fungi

A Zygomycete Life Cycle - 1A Zygomycete Life Cycle - 1

Rhizopus stoliniferRhizopus stolinifer can reproduce sexually can reproduce sexually or asexuallyor asexually

Sexual reproduction occurs, then hyphae Sexual reproduction occurs, then hyphae of mating strains meetof mating strains meet

At point of contact, hyphae form At point of contact, hyphae form gametangia gametangia

A Zygomycete Life Cycle - 2A Zygomycete Life Cycle - 2

Gametangia tips fuse; form zygosporangiumGametangia tips fuse; form zygosporangium

Nuclei inside zygosporangium fuse to Nuclei inside zygosporangium fuse to

produce a diploid zygosporeproduce a diploid zygospore

Zygospore may remain dormantZygospore may remain dormant

Meiosis of zygote nuclei produces haploid Meiosis of zygote nuclei produces haploid

sporesspores

nuclear fusion meiosisDiploid Stage

Haploid Stage

zygospore (2n)

spores (n)

a zygospore b spore sac

mycelium develops from germinated spore

rhizoids

stolonASEXUAL

REPRODUCTION(mitosis)

spores (n)

germinating zygospore

young zygospore

gametangiafusing

contact between hyphae of two mating strains

Fig. 24-6a, p.394

Life Cycle of RhizopusLife Cycle of Rhizopus

Club Fungus Life Cycle - 1Club Fungus Life Cycle - 1

Hyphal cells of two mating strains meetHyphal cells of two mating strains meet

Cytoplasm fuses to form dikaryotic Cytoplasm fuses to form dikaryotic myceliummycelium

Reproductive structure (basidiocarp) formsReproductive structure (basidiocarp) forms

Club Fungus Life Cycle - 2Club Fungus Life Cycle - 2

Spore-bearing structures form on basidiocarpSpore-bearing structures form on basidiocarp

Nuclei fuse to produce a zygoteNuclei fuse to produce a zygote

Zygote undergoes meiosis to produce haploid Zygote undergoes meiosis to produce haploid sporesspores

Spores give rise to haploid myceliaSpores give rise to haploid mycelia

nuclear fusion meiosis

cytoplasmic fusion

Diploid Stage

Haploid Stage

club-shaped structures with two nuclei (n + n) gills

“dikaryotic” (n + n) mycelium

cap

stalk

Spores (n)form

Spores released

Germination, mycelium forms

Club Fungus Life CycleClub Fungus Life Cycle

Fig. 24-7, p. 407

Sac Fungi (Ascomycota)Sac Fungi (Ascomycota)

Most diverse group (30,000 species)Most diverse group (30,000 species) Produce asexual spores called conidiaProduce asexual spores called conidia Produce sexual ascospores in sac-shaped Produce sexual ascospores in sac-shaped

cells call ascicells call asci Multicelled species form reproductive Multicelled species form reproductive

structures called ascocarps that enclose structures called ascocarps that enclose the ascithe asci

Fig. 24-8, p.396

asexual spores

Diploid Stage

Haploid Stagenuclearfusion

meiosisin ascus

mitosis

dispersal,germination

asexual spores

hyphae ofmating strain a

hyphae ofmating strain A

cytoplasmicfusion

diploid (2n) hyphal cell

two A + two aascospores (n)

four A + four aascospores

Example of Sac FungusExample of Sac Fungus

Sarcoscypha coccinia, scarlet cup fungus

Ascospores on the inner cup surface

Fig. 24-8, p.396

Fig. 24-9b, p.396


MorelMorel

Fig. 24-9c, p.396


PenicilliumPenicillium

“Penicillium is a genus of ascomycetous fungi of major importance in the natural environment as well as food and drug production. Members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria inside the body.” http://en.wikipedia.org/wiki/Penicillium

Fig. 24-9d, p.396


Saccharomyces cerevisiaeSaccharomyces cerevisiae

True yeastFermentationSugar Carbon dioxide and EthanolUsed as a model organism in the study of cell biology

In the US, corn is the major feedstockethanol production.

Fungal FoesFungal Foes

Most fungi are vital decomposers and Most fungi are vital decomposers and plant symbiontsplant symbionts

Small proportion are plant pathogensSmall proportion are plant pathogens

Tiny minority adversely affect human Tiny minority adversely affect human healthhealth

Plant PathogensPlant Pathogens

Ascomycetes are responsible for Ascomycetes are responsible for

Chestnut blightChestnut blight

Dutch elm diseaseDutch elm disease

Apple scabApple scab

Basiomycetes cause smuts of cereal grainsBasiomycetes cause smuts of cereal grains

Fig. 24-10b, p.397

Human Pathogens & ToxinsHuman Pathogens & Toxins

Ascomycetes causeAscomycetes cause HistoplasmosisHistoplasmosis Valley feverValley fever Candida Candida (“yeast”) infections(“yeast”) infections RingwormRingworm Athlete’s footAthlete’s foot ErgotismErgotism

Eating some basidiomycetes can be fatalEating some basidiomycetes can be fatal

HistoplasmosisHistoplasmosis

Respiratory disease Respiratory disease Caused by inhalation of spores of Caused by inhalation of spores of

Ajellomyces capsulatusAjellomyces capsulatus Spores are found in soil, especially where Spores are found in soil, especially where

there are bird or bat droppingsthere are bird or bat droppings Can be fatal in people with weakened Can be fatal in people with weakened

immune systemsimmune systems

“Histoplasmosis is a fungal infection caused by inhaling dust from spore-infected bird droppings. The acute form is treated with antifungal medication.”

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002073/figure/A001082.B17222/?report=objectonly

Claviceps purpureaClaviceps purpurea

Ascomycete that parasitizes cereal grainsAscomycete that parasitizes cereal grains

Produces alkaloidsProduces alkaloids Some have been used medicallySome have been used medically

Ingestion causes ergotismIngestion causes ergotism Hallucinations, vomiting, diarrheaHallucinations, vomiting, diarrhea

Lichen: A Composite OrganismLichen: A Composite Organism

Fungal mycobiont plus a photosynthetic Fungal mycobiont plus a photosynthetic

photobiont photobiont

Fungal component usually is ascomyceteFungal component usually is ascomycete

Photobiont is cyanobacteria or green Photobiont is cyanobacteria or green

algaealgae

Fungus composes bulk of the structureFungus composes bulk of the structure

Fig. 24-11a, p.398

LichenLichen

Fig. 24-11b, p.398

LichenLichen

Fig. 24-11c, p.398

LichenLichen

inner layer of loosely woven hyphae

dispersal fragment(cells of fungus and of photosynthetic species)

outer layerof fungal cells

photosynthetic species

outer layer of fungal cells

Fig. 24-11d, p.398

Lichen Cross SectionLichen Cross Section

MycorrhizaeMycorrhizae

Mutualistic fungus and tree roots Mutualistic fungus and tree roots EctomycorrhizaeEctomycorrhizae

Hyphae form net around rootsHyphae form net around roots Common in temperate forestsCommon in temperate forests

Endomycorrhizae Endomycorrhizae Fungus actually enters root cellFungus actually enters root cell Form in 80% of vascular plantsForm in 80% of vascular plants Zygomyetes are the fungal partnersZygomyetes are the fungal partners

Fig. 24-12a, p.399


small, young tree root

hyphal strands

Fig. 24-12b, p.399


Fig. 24-12c, p.399


Fungi in Decline?Fungi in Decline?

Numbers and kinds of mushrooms are Numbers and kinds of mushrooms are decliningdeclining

Decline correlates with rising air pollutionDecline correlates with rising air pollution If the fungal symbionts of trees and other If the fungal symbionts of trees and other

plants are killed, ecosystems will be plants are killed, ecosystems will be disrupted disrupted

Fig. 24-13, p.401

““Fungal ShotgunFungal Shotgun“Pilobolus, known the “Fungal Shotgun”, is a rapidly growing fungus, which inhabits dung. It can fully develop within a week of spore germination. It is a member of the lower fungi and produces a sac-like structure called a sporangium, which contains the spores. This particular sporangium has a lens like vesicle with a light sensitive “retina” at its base. The fungus is positively phototropic causing the sporangium to be aimed towards any light source. Pressure builds up inside the structure, which supports the sporangium until it is more than 100 pounds per square inch. This causes the vesicle to explode propelling the sporangial head in excess of 2 meters. There is mucilaginous substance on the sporangium, which allows it to stick to whatever it lands on.”

PilobolusPilobolus

http://www.youtube.com/watch?v=STK7AZ_Zs_E

The Dance Troup

http://www.youtube.com/watch?v=Z4gK5Kuy1bE

The Fastest Living Thing on Earth

Fig. 24-14, p.401

Fig. 24-15p.401

Fly agaric (Amanita muscaria)

Fig. 24-15b, p.401

fungi lecture 2013

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