Kingdom Fungi

Characteristics

The Characteristics of Fungi Fungi are NOT plants Nonphotosynthetic Eukaryotes Nonmotile Most are saprobes (live on dead organisms)

The Characteristics of Fungi 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 BREAD MOLD

The Characteristics of Fungi Important decomposers & recyclers of nutrients in the environment Most are multicellular, except unicellular yeast Lack true roots, stems or leaves MULTICELLULAR MUSHROOM UNICELLULAR YEAST

The Characteristics of Fungi Cell walls are made of chitin (complex polysaccharide) Body is called the Thallus Grow as microscopic tubes or filaments called hyphae

The Characteristics of Fungi Some fungi are internal or external parasites A few fungi act like predators & capture prey like roundworms Predaceous Fungi feeding on a Nematode (roundworm)

The Characteristics of Fungi Some are edible, while others are poisonous EDIBLE POISONOUS

The Characteristics of Fungi Produce both sexual and asexual spores Classified by their sexual reproductive structures Spores come in various shapes

The Characteristics of Fungi Grow best in warm, moist environments Mycology is the study of fungi Mycologists study fungi A fungicide is a chemical used to kill fungi Fungicide kills leaf fungus

The Characteristics of Fungi Fungi include puffballs, yeasts, mushrooms, toadstools, rusts, smuts, ringworm, and molds The antibiotic penicillin is made by the Penicillium mold Penicillium mold Puffball

Vegetative Structures NON-REPRODUCTIVE

Hyphae 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 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)

Absorptive Heterotroph Fungi get carbon from organic sources Tips of Hyphae release enzymes Enzymatic breakdown of substrate Products diffuse back into hyphae Nucleus “directs” the digestive process Enzymatic breakdown Most enzyme release (and absorption) at tips Proteins and other materials synthesized by the entire mycelium are channeled by cytoplasmic streaming to the tips of the extending hyphae. Enzymes Digested material is then used by the hypha

Modifications of hyphae Fungi may be classified based on cell division (with or without cytokinesis) Aseptate or coenocytic (without septa) Septate (with septa) NO CROSS WALLS CROSS WALLS

Modifications of hyphae HAUSTORIA – parasitic hyphae on plants & animals Septate Hyphae Coenocytic Hyphae

Hyphal growth Hyphae grow from their tips Mycelium is an 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

ASEXUAL & SEXUAL SPORES REPRODUCTIVE STRUCTURES 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

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 Nonmotile Dispersed by wind

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) Dimorphic 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 - + SPORE FORMS

ASexual Reproduction

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 size Used by yeasts Asexual spores – production of spores by a single mycelium

Reproduce by spores Spores may be Formed: Directly on hyphae Inside sporangia On Fruiting bodies Penicillium hyphae Fungi reproduce by releasing spores that are produced either sexually or asexually. The output of spores from one reproductive structure is enormous, with the number reaching into the trillions. Dispersed widely by wind or water, spores germinate to produce mycelia if they land in a moist place where there is food. Pilobolus sporangia Amanita fruiting body

ASEXUAL REPRODUCTION Fruiting Bodies are modified hyphae that make asexual spores An upright stalk called the Sporangiosphore supports the spore case or Sporangium

Types of Fruiting Bodies: Basidia Sporangia Ascus ASEXUAL REPRODUCTION Types of Fruiting Bodies: Basidia Sporangia Ascus Sporangia Basidia

Both are composed of hyphae Fruiting Bodies Both are composed of hyphae mycelium

Hyphal growth from spore Germinating spore Fungal mycelia can be huge, but they usually escape notice because they are subterranean. One giant individual of Armillaria ostoyae in Oregon is 3.4 miles in diameter and covers 2,200 acres of forest, It is at least 2,400 years old, and weighs hundreds of tons. (Actually noone has seen this of this extent – but cultures have been taken from soil over that area and all isolates have been found to be the same individual) Ten cubic centimeters of rich organic soil may have fungal hyphae with a surface area of over 300 cm2 mycelium Mycelia have a huge surface area More surface area aids digestion & absorption of food

Evolution of Fungi

Cladogram Which of the following is most closely related to a mushroom (fungus)? WHY? Recent DNA-based studies show that fungi are more similar to animals than to plants

Molecular studies indicate that animals, not plants, are the closest relatives of fungi. Both Animals and Fungi are related most closely to a group of Protists known as the choanoflagellates (collar flagellates) Kingdom began in ocean during Precambrian (Late Proterozoic era) More than 100,000 species of fungi are known and mycologists estimate that there are actually about 1.5 million species worldwide. Evolution of the Fungi

It’s All About the Spores! Fungi are classified by their REPRODUCTIVE STRUCTURES and SPORES The reproductive structures are: BASIDIA - BASIDIOMYCOTA SPORANGIA - ZYGOSPORANGIA ASCUS - ASCOMYCOTA

It’s All About the Spores! Spores are made of: Dehydrated cytoplasm Protective coat Haploid cell Wind, animals, water, & insects spread spores Spores germinates when they land on a moist surface (new hyphae form)

Classification & Phylogeny asci basidia The phyla of fungi are determined by 1. motility of spores 2. nature of sexual stage Fungi moved onto land with the plants in the Early Paleozoic Much of the evolution of fungi was in conjunction with the evolution of plants and plant parts For example, when roots evolved, fungi were there and helped (mycorrhizas) When wood evolved, fungi evolved to take advantage of it Other evolutionary changes related to animals zygosporangia Classification & Phylogeny motile spores

Major Groups of Fungi

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 Saprobes Decomposers Molds, mushrooms, etc. Parasites Harm host Rusts and smuts (attack plants) Mutualists Both benefit Lichens Mycorrhizas fungi absorb nutrients from nonliving organisms. Parasitic fungi absorb nutrients from the cells of living hosts. Saprobic Some parasitic fungi, including some that infect humans and plants, are pathogenic. Mutualistic fungi also absorb nutrients from a host organism, but they reciprocate with functions that benefit their partner in some way

Major Groups of Fungi Basidiomycota – Club Fungi Zygomycota – Bread Molds Chytridiomycota – Chytrids AM Fungi - Mycorrhizas Ascomycota – Sac Fungi Lichens – Symbiosis (algae & Fungi)

ZYGOmycota

Rhizopus on strawberries Zygomycota Rhizopus on strawberries Called the sporangium fungi Commonly called molds Also includes blights Hyphae have no cross walls (aseptate) Grow rapidly Includes bread mold Rhizopus stolonifer Tomato Blight Most of the 600 zygomycote, or zygote fungi, are terrestrial, living in soil or on decaying plant and animal material. Asexual reproduction in sporangia One zygomycote group form mycorrhizas, mutualistic associations with the roots of plants.

Zygomycota Asexual reproductive structure called sporangium atop sporangiospores make spores Rhizoids anchor the mold & release digestive enzymes & absorb food Stolons connect the fruiting bodies Most of the 600 zygomycote, or zygote fungi, are terrestrial, living in soil or on decaying plant and animal material. Asexual reproduction in sporangia One zygomycote group form mycorrhizas, mutualistic associations with the roots of plants.

Zygomycota Sexual spores are produced by conjugation when (+) hyphae and (-) hyphae fuse Sexual spores are called ZYGOSPORES Zygospores can endure harsh environments until conditions improve Most of the 600 zygomycote, or zygote fungi, are terrestrial, living in soil or on decaying plant and animal material. Asexual reproduction in sporangia One zygomycote group form mycorrhizas, mutualistic associations with the roots of plants. zygospore

Basidiomycota

Basidiomycota Called Club fungi Includes: Mushrooms Toadstools Bracket & Shelf fungi Puffballs Stinkhorns Rusts and smuts Asexual spores conidia Ecologically important on wood as decomposers and parasites Half the mushrooms form mycorrhizas

USES For Basidiomycota Some are used as food (mushrooms) Others damage crops (rusts & smuts) Portobello Mushrooms Soybean Rust Corn Smut

Characteristics of Club Fungi Seldom reproduce asexually The visible mushroom is a fruiting body Basidiocarp (fruiting body) is made of a stalk called the stipe and a flattened cap with gills called Basidia underneath Basidiospores are found on basidia Annulus is a skirt-like ring around some stipes Vegetative structures found below ground

Mushroom Life Cycle Hyphal fusion of haploid mycelia mycelium and fruiting body are dikaryotic haploid mycelium Mushroom Life Cycle N 2N N+N Meiosis Nuclear fusion in basidium young basidia - the only diploid cells Fig 31.12

Ascomycota

Characteristics Called Sac fungi Includes Cup fungi, morels, truffles, yeasts, and mildew May be plant parasites (Dutch elm disease and Chestnut blight) Reproduce sexually & asexually Ascus - sac that makes ascospores in sexual reproduction Specialized hyphae known as Ascocarps contain the asci Mycologists have described over 60,000 species of ascomycetes, or sac fungi. Ascomycota tend to grow from spore to spore in one year and relate well to living plant tissues There is diverse form in the growth and fruiting structures – yeasts to morels, many intermediate (and small) Asexual reproduction by conidia (externally produced, not in sporangia) Half of the Ascomycota form lichens (evolved 8 or more times in different orders) but not all lichens are Ascomycotes

Characteristics Yeasts reproduce asexually by budding (buds break off to make more yeast cells) Asexual spores called conidia form on the tips of special hyphae called conidiophores Mycologists have described over 60,000 species of ascomycetes, or sac fungi. Ascomycota tend to grow from spore to spore in one year and relate well to living plant tissues There is diverse form in the growth and fruiting structures – yeasts to morels, many intermediate (and small) Asexual reproduction by conidia (externally produced, not in sporangia) Half of the Ascomycota form lichens (evolved 8 or more times in different orders) but not all lichens are Ascomycotes CONIDIA

Conidia Formation

Yeasts Budding Saccharomyces Bread and wine yeast, the budding yeast, Saccharomyces Easily cultured. For a time, this was the most important organism for studying the molecular genetics of eukaryotes Thus, Saccharomyces is arguably the most important organism known to humans Candida causes diseases of humans, usually experiencing chemical imbalance or immune problems Saccharomyces

Uses of Ascomycetes Truffles and morels are good examples of edible ascomycetes Penicillium mold makes the antibiotic penicillin. Some ascomycetes also gives flavor to certain cheeses. Saccharomyces cerevesiae (yeast) is used to make bread rise and to ferment beer & wine.

CHYTRIDIOMYCOTA

Chytridiomycota Called chytrids Produce motile spores Mostly saprobes and parasites in aquatic habitats Biodegrade and recycle nutrients Classified in CMR as true fungi (because of their molecular relationships) Remainder of the phyla are almost exclusively terrestrial (a few molds on wet plant material) Chytrid that attacks Potatoes

MYCORRHIZA

Mycorrhizas Fungus associated with plant 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 ecologically Half of the mushroom-forming fungi (basidiomycota) form mycorrhizas with trees Some people think that the spongy tissue in roots evolved as a place where fungi could invade to form early links with plants that helped them survive the harsh life on early earth

Lichens

Lichens Mutualism between: Form a thallus (body) Fungus (structure) Algae or cyanobacteria (provides food) Form a thallus (body) Foliose Fruticose Crustose Thallus is a plant-like body that doesn’t have roots, stems or leaves Thallus doesn’t look like either partner Dual nature of thalli was not fully understood until early 1900’s Fungus gives the name to the lichen (by agreement) Fungus usually, but not always, an Ascomycote (in 8+ independent orders) Algae green. If bluegreen bacteria present, lichens fix nitrogen (turn atmospheric nitrogen into amino acid nitrogen in proteins)

Lichen structure The nature of lichen symbiosis is may also be described as mutual exploitation instead of mutual benefit. Lichens live in environments where neither fungi nor algae could live alone. While the fungi do not grow alone in the wild, some (but not all) lichen algae occur as free-living organisms. If cultured separately, the fungi do not produce lichen compounds and the algae do not “leak” carbohydrate from their cells. In some lichens, the fungus invades algal cells with haustoria and kills some of them, but not as fast as the algae replenish its numbers by reproduction. Lobaria oregana prefers old-growth conifer canopies in forests with clean air.

Lichens as biomonitors Thalli act like sponges Some species more sensitive than others to pollutants Which species are present can indicate air quality Most resistant species can also be analyzed for pollutants Analysis for sulfur and heavy metals in resistant species shows levels relative to levels in the environment