biology i presentation - wcs€¦ · vegetative structure: mycelium may be primary or secondary....

Biology I Presentation

WE WILL LEARN

General characteristics of fungi

Structure of fungi

Economic Importance

Pathogenicity

Brief intro of some fungi

THE SIX KINGDOMS

Fungi are placed in a separate kingdom called the kingdom fungi

CHARACTERISTICS OF FUNGI

THE CHARACTERISTICS OF FUNGI

Fungi are NOT plants

Nonphotosynthetic

Eukaryotes

Nonmotile

Most are saprobes(live on dead organisms)

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Absorptive heterotrophs(digest food first & then absorb it into their bodies

Release digestive enzymes to break down organic material or their host

Store food energy as glycogen

7

BREAD MOLD


Important decomposers& recyclers of nutrients in the environment

Most are multicellular, except unicellular yeast

Lack true roots, stems or leaves

8

MULTICELLULAR MUSHROOM

UNICELLULAR YEAST

FUNGI AS A DECOMPOSERS


Cell walls are made of chitin (complex polysaccharide)

Body is called the Thallus

Grow as microscopic tubes or filaments called hyphae

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Some fungi are internal or external parasites

A few fungi act like predators & capture prey like roundworms

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Predaceous Fungi feeding on

a Nematode(roundworm)


Some are edible, while others are poisonous

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EDIBLE POISONOUS


Produce both sexual and asexual spores

Classified by their sexual reproductive structures

13

Spores come in various shapes


Grow best in warm, moist environments

Mycology is the study of fungi

Mycologists study fungi

A fungicide is a chemical used to kill fungi

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Fungicide kills leaf fungus


Fungi include puffballs, yeasts, mushrooms, toadstools, rusts, smuts, ringworm, and molds

The antibiotic penicillin is made by the Penicillium mold

15

Penicillium mold

Puffball

FUNGI SIZE

Vegetative Structures

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NON-REPRODUCTIVE

HYPHAE

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Tubular shape

ONE continuous cell

Filled with cytoplasm & nuclei

Multinucleate

Hard cell wall of chitin also in insect exoskeletons

HYPHAE

Stolons –horizontal hyphae that connect groups of hyphae to each other

Rhizoids – rootlike parts of hyphae that anchor the fungus

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STOLON

RHIZOIDS

HYPHAE

Cross-walls called SEPTA may form compartments

Septa have pores for movement of cytoplasm

Form network called mycelia that run through the thallus(body)

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ABSORPTIVE HETEROTROPH

Fungi get carbon from organic sources Tips of Hyphae release enzymes Enzymatic breakdown of substrate Products diffuse back into hyphae

Digested material is then used by the hypha

Nucleus “directs” the digestiveprocess

MODIFICATIONS OF HYPHAE

Fungi may be classified based on cell division (with or without cytokinesis)

Aseptate or coenocytic (without septa)

Septate (with septa)

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NO CROSS WALLS CROSS

WALLS

MODIFICATIONS OF HYPHAE

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HAUSTORIA – parasitic hyphae on plants & animals

Septate Hyphae Coenocytic Hyphae

HYPHAL GROWTH

Hyphae grow from their tipsMycelium is an extensive, feeding web of hyphae

Mycelia are the ecologically active bodies of fungi

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This wall is rigid Only the tip wall is plastic and stretches

REPRODUCTIVE STRUCTURES

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ASEXUAL & SEXUAL SPORES

REPRODUCTION

Most fungi reproduce Asexually and Sexually by spores

ASEXUAL reproduction is most common method & produces genetically identical organisms

Fungi reproduce SEXUALLY when conditions are poor & nutrients scarce

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SPORES

Spores are an adaptation to life on land

Ensure that the species will disperse to new locations

Each spore contains a reproductive cell that forms a new organism

NonmotileDispersed by wind

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HYPHAL GROWTH FROM SPORE

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Mycelia have a huge surface area More surface area aids digestion & absorption of food

mycelium

Germinating spore

GENERALIZED LIFE CYCLE OF A FUNGUS

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SEXUAL REPRODUCTION

SEXUAL REPRODUCTION

Used when environmental conditions are poor (lack of nutrients, space, moisture…)

No male or female fungi

Some fungi show dimorphism

May grow as MYCELIA or a YEAST –LIKE state (Filament at 25oC & Round at 37oC)

31Dimorphic Fungi

SEXUAL REPRODUCTION

Haploid 1n hyphae from 2 mating types (+ and -) FUSE (Fertilization)

Forms a hyphae with 2 nuclei that becomes a ZYGOTE

The zygote divides to make a SPORE

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+ -

SPORE FORMS

ASEXUAL REPRODUCTION

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THREE TYPES OF ASEXUAL REPRODUCTION

Fragmentation – part of the mycelium becomes separated & begins a life of its own

Budding – a small cell forms & gets pinched off as it grows to full sizeUsed by yeasts

Asexual spores – production of spores by a single mycelium

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REPRODUCE BY SPORES

Spores may be Formed:Directly on hyphaeInside sporangiaOn Fruiting bodies

Amanita fruiting bodyPilobolus sporangia

Penicilliumhyphae

ASEXUAL REPRODUCTION

Fruiting Bodies are modified hyphae that make asexual spores

An upright stalk called the Sporangiosphore supports the spore case or Sporangium

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Major Groups of Fungi

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MAJOR GROUPS OF FUNGI

Within the past few years, several groups have been re-classified into the protists

Two of these groups are the slime molds and water molds

Classification by Nutrition

SaprobesDecomposersMolds, mushrooms, etc.

ParasitesHarm hostRusts and smuts (attack plants)

MutualistsBoth benefitLichensMycorrhizas

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Basidiomycota – Club Fungi

Zygomycota – Bread Molds

Chytridiomycota – Chytrids

AM Fungi - Mycorrhizas

Ascomycota – Sac Fungi

Lichens – Symbiosis (algae & Fungi)

ASCOMYCOTA CHYTRIDIOMYCOTA


BASIDIOMYCOTA ZYGOMYCOTA

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MYCORRHIZALichens

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HUMAN-FUNGUS INTERACTIONS

Beneficial Effects of Fungi Decomposition - nutrient and carbon recycling. Biosynthetic factories. Can be used to produce

drugs, antibiotics, alcohol, acids, food (e.g., fermented products, mushrooms).

Model organisms for biochemical and genetic studies.

Production of vitamin Hormone production Edible fungi Production of insecticides

FUNGI FORM BENEFICIAL PARTNERSHIPS (SYMBIOSIS) WITH OTHER ORGANISMS SUCH AS TREES AND FLOWERING PLANTS:

Lichen – symbiotic relationship between algae

and fungi

Algae

hyphae

HUMAN-FUNGUS INTERACTIONS

Harmful Effects of FungiDestruction of food, lumber, paper, and cloth. Plant diseases. Animal diseases human diseases, including allergies.Toxins produced by poisonous mushrooms and

within food (e.g., grain, cheese, etc.).

Fungi as Parasites & Pathogens

SOME EXAMPLES OF FUNGI ARE

.

Puccunia penicillium

Phythophtora ustilago

PUCCINIA..

PUCCINIA

Systematic Position

Division : Mycota (Basidiomycota)

Subdivision: Eumycota

Class: Basidiomycetes

Order: Uredinales

Family: pucciniacea

HABIT AND HABITAT

Puccinia are generally known as rust fungi.

700 species

They are parasites on plants(wheat, coffee, beans etc).

It is an internal obligate parasite.

They are generally heteroecious, i.erequiring two hosts to complete life cycle.

MORPHOLOGICAL FEATURES

Delicate septate mycellia

. It is intercellular

sending out haustoria in the host cells

penetrating the host cell causes hypertrophy, distortion and malformation

The mycelium is monokaryotic on secondary host and dikaryotic on primary host

HAUSTORIA

REPRODUCTION

life cycle on two different hosts. The diplophase (2n) stage is a parasite on wheat

while

the haplophase (1n) stage on an alternate host which is Barberry vulgaris.

We’ll take example of Puccin graminisia

LIFE CYCLE

Its life cycle spreads over five stages, which are

a.Uredinial stage:-

b.Telial stage:-

c.Basidial stage:-

d.Spermogonial stage or pycnidialstage:-

e.Aecial or Aecidial stage:-

A.UREDINIAL STAGE:-

first or rust stage. appear on culms, The pustule is called a Uredinium, which on maturity bursts and releases uredospores.

Each uredospore is a binucleate Lying together -red-rust like appearance readily germinate on wheat plant

Wheat rust ( Puccinia ) Uredospores are small, roughly circular, thick-walled reddish spores found within ruptured rust...

B.TELIAL STAGE:-

dark brown or black pustules

occur in the form of streaks called telia

Containing teliospores or teleutospores(dark brown )

diploid nucleus

.

b.Telial stage:-

C.BASIDIAL STAGE:-

, nuclear fusion a row of four haploid nucleus. This four celled structure is called a

promycelium or epibasidium Tube formation…-basidiospore Formation of spores each spore is either of + or – strain Basidiospore detach… now ready to infect

D.SPERMOGONIAL STAGE OR PYCNIDIAL STAGE:-

basidiospores germinate . to attack barberry leaves

mycelia spreads ( huastoria)

barberry protoplasm ( their only food )

Monokaryotic mycellium (+ or – strain )

Afterfour days 2 structure formed

1.Pycnia or spermogonia on upper surface

2.Aedia or cluster cups on ventral surface

E.AECIAL OR AECIDIAL STAGE:-

Aecia, aecidia or cluster cups are produced as little yellow cups on ventral surface of barberry leaf.

AECIAL OR AECIDIAL STAGE

Spermatization Formation of aecidiospores. These are binucleate and brightly yellow

coloured and they germinate on wheat blown by wind having six germ pores Entering in host through stomata Life cycle continues

ECONOMIC IMPORTANCE:-

Puccinina graminis tritici causes black or stem rust,

P. recondita causes brown or orange leaf rust

P.coronata brown rust of wheat

P. sorghi causes leaf rust of corn

USTILAGO

SYSTEMATIC POSITION

Division Mycota

Sub division Eumycota

Class Basidiomycetes

Order Ustilagonales

Family Ustilaginaceae

HABIT AND HABITAT:

400 species

internal parasites of plants

Causing diseases called smuts because of black coloured spores.

VEGETATIVE STRUCTURE:

mycelium may be primary or secondary. Primary mycelium is uninucleate and is called

monokaryotic mycelium. Secondary mycelium is septate, dikaryotic and

spreads throughout interior of the host plant Firstly intracellular and later on becomes

intercellular. Mycelluim sending huastoria into the host infection appearance in flowering stage (loose

smut ) , dark brown powder, ( easily blown by wind ) And host destroyed

REPRODUCTION:

Chlamydospore formation mycellium accumulation Division and redivision Hyphae swelling brandspores, smut spores or

chlamydospores, formation ( the black spores )

beaded appearance to the hyphae. This rusty mass or group of black spores

is called the smut

Hyphae swelling

CHLAMYDOSPORE rounded or oval in shape covered by a two layered wall outer thick layer called exospore an inner delicate and smoothn layer called

endosperm. after dispersal fall on soil and lead a

saprophytic life basisiospore or a sporidium formation Germination .after germination basidiospores are

capable of infecting

CHLAMYDOSPORE

Life cycle of ustilago

ECONOMIC IMPORTANCE:

1.Loose smut of wheat is caused by Ustilago tritici and is a common disease


2.it causes about 1% damage in the planes and around 10-20% in foot hills and humid places of Pakistan.

3. Covered smut of barley is caused by U.hordei and U.nuda.


4. Loose smut of maize is caused byU.maydis or U.zeae


5. sugar cane is attacked by U.scitamineaor U.sacchari and U.avenae cause loose smut of oat.

biology i presentation - wcs€¦ · vegetative structure: mycelium may be primary or secondary....

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