Fungal Diversity - lec 1

• Introduction • Morphology • Reproduction & Dispersal • Ecological roles: Recyclers, Mutualists, Pathogens, Parasites, and Predators

Characteristics of ALL Fungi

Chitin

Heterotrophs

Chitin:

tough and flexible molecule (similar to, but stronger, than cellulose)

Absorptive nutrition- saprobes:

(type of decomposer): absorb nutrients from dead organic matter

mutualists:

gain AND receive nutrients from their partners (fish and sharks)

parasites:

non mutual benefit, absorb nutrients from living hosts (baby and pregnant mother)

Animals eat their food and digest it:

engulf and digest internally and absorb nutrients from the gut.

Fungi live in their food:

externally secrete digestive enzymes and transport products (e.g., sugars, amino acids, peptides) into their cells.

Both fungi and animals are…

heterotrophs: obtain both energy and carbon from consuming (organic) material, but (live in vs eat food)

Plants are

(photo)autotrophic

fungi are

(chemo)heterotrophic

Both fungi and plants have _____, but fungi use _____ instead of cellulose and lignin for support

cell walls, chitin

Fungal Chemotropism

• Most fungi grow towards their food chemotropism (respond to chemical stimuli)

• Grow toward chemicals released by food (e.g., like animals smelling food)

• Growth occurs at the tip, like a root

Single celled form of fungi

unicellular members of several different groups (not always multicellular)

Commonly known as yeast

structural characteristics of multicellular fungi

hypha

mycelium

Hyphae

Composed of tubular filaments

high surface-to-volume ratio for absorbing nutrients

Mycelium

Network of hyphae

a branching network of hyphae and the “fungal body”, like plant roots, used for absorption & structure, but also used in decomposition (unlike plant roots)

has a high surface area-to-volume ratio: good for acquisition of water and nutrients

What we see of fungi is often the ____ (aboveground) (e.g., a mushroom)

“fruiting body”

Fruiting body produces…

spores

Asexual (“without sex”) reproduction:

haploid spores produce haploid hyphae that give rise to more haploid spores (most common)

Sexual reproduction:

fusion of haploid hyphae of different mating types

Why do fungi have "mating types" instead of sexes?

because they are morphologically identical and often have more than two mating types.

Sexual Reproduction - Fusion of two haploid hyphae of different mating types produces

dikaryotic hyphae

Dikaryon:

a cell with two genetically different haploid nuclei (one from each parent hypha)

Syngamy (fertilization) requires two sequences:

1) plasmogamy: fusion of the cytoplasm

2) karyogamy: fusion of the nuclei

Spores can be produced from ______ OR ______

meiosis (sexual reproduction), mitosis (asexual reproduction)

Roles of Fungi: Saprobes

Soil formation

Nutrient recycling

Roles of Fungi: Mycorrhizae

plant roots + fungal hyphae

present in some of the earliest land plants!

Nearly ALL vascular plants have mycorrhizae!!

Mycorrhizae - Fungus

Hyphae penetrates soil around/in plant roots, increasing surface area (more water/minerals/nutrients absorbed).

Mycorrhizae - Plant

Provides carbon compounds (e.g., sugars, amino acids) → products of photosynthesis.

Roles of Fungi: Lichen

fungus + photosynthetic organism (either cyanobacterium, unicellular algae, or both)

First to establish in harsh environments

Sensitive to toxic compounds (indicators of air pollution)

Lichen - Fungus provides

protection, attachment, acquisition of water, minerals.

Lichen - Algae or cyanobacteria provides

carbon compounds (e.g., sugars, amino acids).

Ants depend on

fungus (food), AND bacterium (to control fungus parasite)

Mutualist bacteria controls

parasitic fungus that co-evolved with ant

Fungi: Parasites

• Hyphae invade plant or animal tissue (with enzymes or pressure)

• Grow inside, absorb nutrients

• Often disperse spores outside host (e.g., Cordyceps, a fungal parasite of insects)

Fungi: eukaryotic organisms that are…

more closely related to animals than to plants

Chytridiomycota

“flagellated spore” fungi

Zygomycota

“conjugative” fungi

Basidiomycota

“stalked spore” fungi - spores on a pedestal

Ascomycota

“cup” fungi (& morels) - little sacs “honycomb”