Fungi

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Morphology and classification

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Kingdom Fungi : 

Kingdom Fungi Reported by: Rhea M. Semolava

Slide 2: 

Myco = fungus logy = study Mycology

What is fungi? : 

What is fungi? Fungi is a group of simple plants that have no chlorophyll. There are some species of fungi that are single celled organisms, and there are other kinds of fungi that are multi-cellular organisms. Fungi are made up of filaments called hyphe that are stacked together from end to end. Some kinds of fungi live on land and other types of fungi live in water environments.

Morphology : 

Morphology Mold covering a decaying peach over a period of six days. The frames were taken approximately 12 hours apart.

Slide 5: 

Most fungi grow as thread-like filamentous microscopic structures called hyphae, which are microscopic filaments between 2–10 µm in diameter and up to several centimeters in length, and which collectively form the mycelium. Hyphae can be septate, i.e., divided into compartments separated by a septum, each compartment containing one or more nuclei, or can be coenocytic, i.e., lacking hyphal compartmentalization.

Slide 6: 

However, septa have pores, such as the dolipore septa in the basidiomycetes that allow cytoplasm, organelles, and sometimes nuclei to pass through. Coenocytic hyphae are essentially multinucleate supercells. Many species have developed specialized structures for nutrient uptake from living hosts; examples include haustoria in plant parasites of most phyla, and arbuscules of several mycorrhizal fungi, which penetrate into the host cells to consume nutrients.

The Characteristics of Fungi : 

The Characteristics of Fungi Fungi are NOT plants Hyphae = tubular units of construction Heterotrophic by absorption Reproduce by spores Ecologically pivotal roles

Hyphae : 

Hyphae Tubular Hard wall of chitin Crosswalls may form compartments (± cells) Multinucleate Grow at tips

Heterotrophic by Absorption : 

Heterotrophic by Absorption Fungi get carbon from organic sources Hyphal tips release enzymes Enzymatic breakdown of substrate Products diffuse back into hyphae Enzymes Enzymatic breakdown Products Product diffuses back into hypha and is used Nucleus hangs back and “directs”

Modifications of hyphae : 

Modifications of hyphae Fig 30.2 (don’t worry about the terms)

Hyphal growth : 

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

Reproduce by spores : 

Reproduce by spores Spores are reproductive cells Sexual Asexual Formed: Directly on hyphae Inside sporangia Fruiting bodies Amanita fruiting body Pilobolus sporangia Penicillium hyphae

Hyphal growth from spore : 

Hyphal growth from spore mycelium germinating spore Mycelia have a huge surface area

Slide 15: 

Fig 31.1 mycelium fruiting bodies both are composed of hyphae

Fungal Ecology or nutrition : 

Fungal Ecology or nutrition Saprobes Decomposers Mostly of plants, some animals Parasites Harm host Mostly on plants, some animals Mutualists Lichens Mycorrhizas Others

Classification of fungi : 

Classification of fungi Eumycophyta Myxomycophyta

Phylum myxomycophyta : 

Phylum myxomycophyta There are hundreds of different species of slime molds which are widespread in damp places such as decaying leaves and logs, lawns, living plant stems and even old discarded mattresses. Some masses can grow to form a huge glob.

Slime molds : 

Slime molds

Slime molds : 

Slime molds Each spore of a slime mold hatches into a swimming sex cell and these cells fuse in pairs to form amoeba-like organisms which feed on bacteria and other organic matter. Chemical signals cause the amoeboid cells to come together in a large mass called a plasmodium. The plasmodium might look like a gooey sheet in one species or a crawling slug in another slime mold. Fruiting bodies grow up from the plasmodium and spores are formed which give rise to a new generation.

Plasmodial slime molds : 

Plasmodial slime molds Plasmodial slime molds, of the phylum Myxomycota, are basically enormous single cells with thousands of nuclei. About 500 species are known. Plasmodial slime molds are formed when individual flagellated cells swarm together and fuse. The result is one large bag of cytoplasm with many diploid nuclei. In the motile phase, this multinucleate, or coenocytic, mass, called a plasmodium, creeps about by amoeboid movement.

Slide 22: 

Classification & Phylogeny motile spores zygosporangia asci basidia Fig 31.4

Chytridiomycota – “chytrids” : 

Chytridiomycota – “chytrids” Simple fungi Produce motile spores Mostly saprobes and parasites in aquatic habitats Fig 31.5 Chytridium growing on spores

Zygomycota – “zygote fungi” : 

Zygomycota – “zygote fungi” Sex - zygosporangia Asex - common Hyphae have no cross walls Grow rapidly Mycorrhizas Fig 31.6 Rhizopus on strawberries

Molds : 

Molds Rapidly growth Asexual spores Many human importances Food spoilage Food products Antibiotics, etc. Fig 31.21 Antibiotic activity Noble Rot - Botrytis

Ascomycota – “sac fungi” : 

Ascomycota – “sac fungi” Sex. – asci Asex. – common Cup fungi, morels, truffles Important plant parasites & saprobes Yeast - Saccharomyces Most lichens A cluster of asci with spores inside

Yeasts : 

Yeasts Single celled fungi Adapted to liquids Plant saps Water films Moist animal tissues Candida Saccharomyces

Basidiomycota – “club fungi” : 

Basidiomycota – “club fungi” Sex – basidia Asex – not so common Long-lived dikaryotic mycelia Rusts & smuts – primitive plant parasites Mushrooms, polypores, puffballs Enzymes decompose wood Mycorrhizas

Examples: mushrooms, bracket fungi, puffballs : 

Examples: mushrooms, bracket fungi, puffballs

Slide 30: 

A rust growing on a currant leaf 0.5 cm Other example of fungi Mycorrhizas Lichens

Mycorrhizas : 

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!

“Ecto”mycorrhizas : 

“Ecto”mycorrhizas Russula mushroom mycorrhizas on Western Hemlock root Fungal hyphae around root and between cells Mycorrhiza cross sections

Slide 33: 

Lichens are inherently attractive, the more so the more you observe them. They are colourful - greens, greys, oranges and yellows are common colours. Cladonias often have bright red fruiting bodies adding to their attractiveness. The real beauty of lichens however is in their intricate shapes and often three dimensional forms..

Lichens : 

Lichens “Mutualism” between Fungus – structure Alga or cyanobacterium – provides food Form a thallus Foliose Fruticose Crustose Fig 31.16

Crustose Lichens : 

Crustose Lichens Crustose lichens, as their name implies, form a crust on the surface of the substrate on which they are growing. This crust can be quite thick and granular or actually embedded within the substrate. In this latter case the fruiting bodies still rise above the surface. In many crustose lichens the surface of the thallus breaks up into a cellular, crazy-paving like pattern. Crustose lichens tend to grow out from their edges and have their fruiting bodies in their centre. Crustose lichens are very difficult to remove from their substrates.

Lichen internal structure : 

Lichen internal structure Fig 31.17 Lobaria

Foliose Lichens : 

Foliose Lichens These have an upper and lower cortex. They are generally raised to some extent above the substrate but connected to it by rhizines (specialised root-like hyphae). They are easier to remove from their substrate when collecting because of this.

Fruticose Lichens : 

Fruticose Lichens Fruticose lichens are shrubby lichens. They are attached to their substrate by a single point and rise, or more usually, dangle from this. Some foliose lichens can be stubby like fruticose lichens, however, close examination will reveal that the algal part exists only on one side of the flattish thallus whereas in fruticose lichens it exists as a ring around the thallus, even when it is flattened as in Ramalina sp.

Growth and Development in Lichens : 

Growth and Development in Lichens Lichens will and do grow on just about everything, natural or manmade. Different species of lichens prefer, or only grow on different substrates. Thus some species will be found on smooth barked trees, some on rough barked and some on only one species of tree. Also some lichens grow on basic rocks while others only grow on acidic rocks and some have particular mineral requirements, thus Acarospora sinopica only grows on rocks with a high iron content.

Slide 40: 

However where ever they grow lichens grow slowly so what ever it is they are growing on, the 'substrate' needs to have been around for a few years. Lichens grow differently at different times in their lives. When young and very small they grow slowly, then once they are reasonably well established they grow much more quickly, obviously when they are dying, for what ever reason they grow more slowly again, or not at all.

Lichens as biomonitors : 

Lichens as biomonitors Thalli act like sponges Some species more sensitive Which species are present can indicate air quality (Most resistant species can also be analyzed for pollutants)