1. The 2N megasporocyte nucleus undergoes meiosis to produce haploid nuclei.

2. One of these 1N nuclei divides multiple times by mitosis, producing several 1N clones. (The function of most of these cells is unknown.)

Fig. 38.4

3. Double fertilization produces a 2N zygote and 3N endosperm

Kingdom Fungi

Characteristics of Fungi

• Fungi are NOT plants

• Absorptive heterotrophs• Reproduce by spores

* reproductive bodies are often the most visible

• “Ecologically active”* hyphae = tubular units

of construction* secrete exoenzymes

Justify this statement…

Briefly describe an example in each of the following fungal lifestyles:•decomposers•parasites•symbionts

Fig 31.1

mycelium

fruiting bodies

both are composed of hyphae

Fig 28.8

Proposed Phylogeny of Eukaryotes

(Protista) Fig 32.2

??

motile spores

zygosporangia ascibasidia

Fig 31.4

Classification in these three phyla is based on sexual reproductive structures

Where do chytrids live?

Hyphae

• tubular

• hard wall of chitin around the cell membrane

• septa (perforated cross-walls) may form compartments (± cells)

• multinucleate

What do you think is the purpose of perforated cross-walls?*80% of plant diseases are caused by

fungi

Coenocytic hypha

Septate hypha

Haustoria*

Hyphal growth

• Hyphae grow from their tips• Mycelium = extensive, feeding web of hyphae

• Mycelia are the ecologically active bodies of fungi

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

Where would you find the hyphae of most fungi?

Why is SA important?

What does absorptive heterotrophic nutrition look like?• Fungi get their energy and raw materials from

organic sources in their environment

• The products of digestion diffuse back into hyphae

Products diffuses backinto hyphae for use

Nucleus “hangs back”and directs metabolism

Modifications of hyphae

Fig 30.2 (don’t worry about the terms we don’t discuss in class)

Reproduction by spores• Spores are reproductive cells

* Sexual* Asexual

• Produced* fruiting bodies* inside sporangia* directly on hyphae

Amanita fruiting body(Basidomycota)

Pilobolus sporangia(Zygomycota)

Penicillium hyphae(Ascomycota)

Classification of fungi is based on which mode of spore production?

What is the primary purpose of spores?

Fungal Ecology

• Saprobes* Decomposers* Mostly of plants, some animals

• Parasites* Harm host* Mostly on plants, some animals

• Mutualists* Lichens* Mycorrhizas

Zygomycota – “zygote fungi”

• Sexual - zygosporangia

• Asexual spores - common

• Hyphae have no cross walls

• Grow rapidly

Fig 31.6 Rhizopus on strawberries

Fig 31.7 Life cycle of RhizopusYou are not responsible for the details of this life cycle. Life cycle is predominantly haploid

Asexual sporangium with spores inside

Sexual zygsporangium with one zygospore

Fig. 31.7

Ascomycota – “sac fungi”

• Sex. – asci

• Asex. – common

• Cup fungi, morels, truffles

• Important plant parasites & saprobes

• Yeast - Saccharomyces

• Most lichensA cluster of asci with spores inside

Ascomycota – “sac fungi”

Aleuria

1 cm

Fig 31.9b Tuber melanosporum The black french truffle

Basidiomycota – “club fungi”

• Sex – basidia

• Asex – not so common

• Long-lived mycelia

• Rusts & smuts – primitive plant parasites

• Mushrooms, puffballs

• Enzymes decompose wood

• Mycorrhizas

SEM of basidia and sporesSee Fig. 31.12

From: http://botit.botany.wisc.edu/toms_fungi/mar2003.html

Marasmius oreades - “Fairy Ring”

A rust growing on a currant leaf

0.5 cm

Inocybe, contains muscarine

Boletus edulis

Cantharellus, the chanterelle

Amanita, “death angel”

Fomitopsis

Mushroom Life Cycle

Fig 31.12

Nuclear fusion in basidium

Meiosis

Hyphal fusion of haploid myceliahaploid

mycelium

young basidia - the only diploid cells

mycelium and fruiting body are dikaryotic

N 2N N+N

“Alternative” fungal lifestyles

• Yeasts

• Molds

• Mycorrhizas

• Lichens

Yeasts

• Single celled fungi

• Adapted to liquids* Plant saps

* Water films

* Moist animal tissues

CandidaSaccharomyces

Molds• Rapidly growth• Asexual spores• Many of human importance

* Food spoilage* Food products* Antibiotics, etc.

Fig 31.21 Antibiotic activityNoble Rot - Botrytis

Mycorrhizas• “Fungus roots”

• Mutualism between:* Fungus (nutrient & water uptake for plant)

* Plant (carbohydrate for fungus)

• Several kinds* Zygomycota – hyphae invade root cells

* Ascomycota & Basidiomycota – hyphae invade root but don’t penetrate cells

• Extremely important ecological role of fungi!

Lichens• “Mutualism” between

* Fungus – structure* Alga or

cyanobacterium – provides food

• Form a thallus* Foliose* Fruticose* Crustose

Fig 31.16

By what process do these symbionts produce food for the fungus?

Lichen internal structure

Lobaria

Fig 31.17

What do the fungi provide in this symbiotic relationship?

Lichens as biomonitors

• Thalli act like sponges* Airborne dust, minerals, etc. adsorb to the

lichen surface

• Some species more sensitive• Which species are present can indicate air

quality• Most resistant species can also be analyzed

for pollutants

Lichen diversity

These photos taken by Fred Rhoades

Visit: Fred Rhoade's Lichen Page

Caloplaca & Verrucaria

Two species in the fruticose lichen of the genus, Cladonia

Peltigera

Basidiomycote lichen, Omphalina

1 cm