KINGDOM FUNGI*

Characteristics*

EukaryotesMost are saprobes (live on dead organisms)Grow best in warm, moist environmentsMycology is the study of fungi

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Absorptive heterotrophs (digest food first & then absorb it into their bodiesRelease digestive enzymes to break down organic material or their hostStore food energy as glycogenBREAD MOLD*

Cell walls are made of chitin (complex polysaccharide)Body is called the ThallusGrow as microscopic tubes or filaments called hyphae

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Produce both sexual and asexual sporesClassified by their sexual reproductive structures

Spores come in various shapes*

Vegetative Structures*

Tubular shapeONE continuous cellFilled with cytoplasm & nucleiMultinucleateHard cell wall of chitin also in insect exoskeletons*

Stolons horizontal hyphae that connect groups of hyphae to each otherRhizoids rootlike parts of hyphae that anchor the fungus*STOLONRHIZOIDS

Cross-walls called SEPTA may form compartmentsSepta have pores for movement of cytoplasmForm network called mycelia (non reproductive) that run through the thallus (reproductive body)*

ABSORPTIVE HETEROTROPHFungi get carbon from organic sourcesTips of Hyphae release enzymesEnzymatic breakdown of substrateProducts diffuse back into hyphaeDigested material is then used by the hyphaNucleus directs the digestive process

Hyphae grow from their tipsMycelium is an extensive, feeding web of hyphaeMycelia are the ecologically active bodies of fungiThis wall is rigidOnly the tip wall is plastic and stretches*

REPRODUCTIVE STRUCTURESASEXUAL & SEXUAL SPORES*

REPRODUCTIONMost fungi reproduce Asexually and Sexually by sporesASEXUAL reproduction is most common method & produces genetically identical organismsFungi reproduce SEXUALLY when conditions are poor & nutrients scarce*

SPORESSpores are an adaptation to life on landEnsure that the species will disperse to new locationsEach spore contains a reproductive cell that forms a new organismNonmotileDispersed by wind*

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SEXUAL REPRODUCTIONUsed when environmental conditions are poor (lack of nutrients, space, moisture)No male or female fungiSome fungi show dimorphismMay grow as MYCELIA or a YEAST LIKE state (Filament at 25oC & Round at 37oC)

*Dimorphic Fungi

SEXUAL REPRODUCTIONHaploid 1n hyphae from 2 mating types (+ and -) FUSE (Fertilization)Forms a hyphae with 2 nuclei that becomes a ZYGOTEThe zygote divides to make a SPORE

*+-SPORE FORMS

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THREE TYPES OF ASEXUAL REPRODUCTIONFragmentation part of the mycelium becomes separated & begins a life of its ownBudding a small cell forms & gets pinched off as it grows to full sizeUsed by yeasts

Asexual spores production of spores by a single mycelium*

Spores may be Formed:Directly on hyphaeInside sporangiaOn Fruiting bodiesAmanita fruiting bodyPilobolus sporangiaPenicillium hyphae

Fruiting Bodies are modified hyphae that make asexual sporesAn upright stalk called the Sporangiosphore supports the spore case or Sporangium*

Types of Fruiting Bodies:BasidiaSporangiaAscus*BasidiaSporangia

myceliumFruiting BodiesBoth are composed of hyphae*

Mycelia have a huge surface areaMore surface area aids digestion & absorption of foodmyceliumGerminating spore*

Evolution of Fungi*

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*

Evolution of the Fungi

Fungi are classified by their REPRODUCTIVE STRUCTURES and SPORESThe reproductive structures are: BASIDIA - BASIDIOMYCOTASPORANGIA - ZYGOSPORANGIA ASCUS - ASCOMYCOTA

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Spores are made of: Dehydrated cytoplasm Protective coat Haploid cellWind, animals, water, & insects spread sporesSpores germinates when they land on a moist surface (new hyphae form)

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Classification & Phylogenymotile sporeszygosporangiaascibasidia*

Major Groups of Fungi*

MAJOR GROUPS OF FUNGIWithin the past few years, several groups have been re-classified into the protistsTwo of these groups are the slime molds and water molds

SaprobesDecomposersMolds, mushrooms, etc.ParasitesHarm hostRusts and smuts (attack plants)MutualistsBoth benefitLichensMycorrhizas*

MAJOR GROUPS OF FUNGIBasidiomycota Club FungiZygomycota Bread MoldsChytridiomycota ChytridsAscomycota Sac FungiLichens/Mycorrhizas Symbiosis (plant or algae & Fungi)

ZYGOMYCOTA*

Called the sporangium fungiCommonly called moldsAlso includes blightsHyphae have no cross walls (aseptate)Grow rapidlyIncludes bread mold Rhizopus stoloniferRhizopus on strawberriesTomato Blight

Asexual reproductive structure called sporangium atop sporangiospores make sporesRhizoids anchor the mold & release digestive enzymes & absorb foodStolons connect the fruiting bodies

Sexual spores are produced by conjugation when (+) hyphae and (-) hyphae fuseSexual spores are called ZYGOSPORESZygospores can endure harsh environments until conditions improvezygospore

BASIDIOMYCOTA*

Called Club fungiIncludes:MushroomsToadstoolsBracket & Shelf fungiPuffballsStinkhornsRusts and smuts

Some are used as food (mushrooms)Others damage crops (rusts & smuts) Corn SmutSoybean RustPortobello Mushrooms

CHARACTERISTICS OF CLUB FUNGISeldom reproduce asexuallyThe visible mushroom is a fruiting bodyBasidiocarp (fruiting body) is made of a stalk called the stipe and a flattened cap with gills called Basidia underneathBasidiospores are found on basidiaAnnulus and Volvais a skirt-like ring around some stipesVegetative structures found below ground: Mycelium*

Fig 31.12Nuclear fusion in basidiumMeiosisHyphal fusion of haploid myceliahaploid myceliumyoung basidia - the only diploid cellsmycelium and fruiting body are dikaryoticN 2N N+N*

ASCOMYCOTA*

Called Sac fungiIncludes Cup fungi, morels, truffles, yeasts, and mildewMay be plant parasites (Dutch elm disease and Chestnut blight)Reproduce sexually & asexuallyAscus - sac that makes ascospores in sexual reproductionSpecialized hyphae known as Ascocarps contain the asci

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 conidiophoresCONIDIA

CONIDIA FORMATION*

YEASTS BUDDINGSaccharomyces

Truffles and morels are good examples of edible ascomycetesPenicillium 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*

Called chytridsProduce motile spores (flagella)Mostly saprobes and parasites in aquatic habitatsBiodegrade and recycle nutrientsChytrid that attacks Potatoes

MYCORRHIZA*

MYCORRHIZASFungus associated with plant rootsMutualism between:Fungus (nutrient & water uptake for plant)Plant (carbohydrate for fungus)Extremely important ecologically*

LICHENS*

LICHENSMutualism between:Fungus (structure)Algae or cyanobacteria (provides food)Form a thallus (body)Foliose (leaf-like)Fruticose (shrub-like)Crustose (Crust-like)

LICHEN STRUCTURE*

***********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.**********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.

****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

***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.

***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***fungi absorb nutrients from nonliving organisms.

Parasitic fungi absorb nutrients from the cells of living hosts. SaprobicSome 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***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.

*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.

*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.

**Asexual spores conidia

Ecologically important on wood as decomposers and parasitesHalf the mushrooms form mycorrhizas****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 tissuesThere 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

*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 tissuesThere 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

**Bread and wine yeast, the budding yeast, SaccharomycesEasily cultured. For a time, this was the most important organism for studying the molecular genetics of eukaryotesThus, Saccharomyces is arguably the most important organism known to humansCandida causes diseases of humans, usually experiencing chemical imbalance or immune problems***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)**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*Thallus is a plant-like body that doesnt have roots, stems or leavesThallus doesnt look like either partner

Dual nature of thalli was not fully understood until early 1900s

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)*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.