Matt Ponzini, Shane D’Cruz, and Nikhil Popat

 Diversity of Fungi  100,000+ species of Fungi are known (Estimated to be 1.5 Million worldwide)  Fungi Classified into 4 divisions

 Division Chytridiomycota  Link between Fungi and Protists  Chytrids are mainly aquatic  Absent of flagellated cells as a membership requirement for Kingdom Fungi  Chytrids are classified as Protists though  Recent studies show Chytrids and Fungi have similar sequences of proteins and nucleic acids  Fungal Characteristics of Chytrids  Absorptive mode of nutrition  Cell walls made of chitin  Also contain some key enzymes and metabolic pathways common among Fungi  Molecular evidence supports hypothesis that Chytrids are the most primitive Fungi  Fungi evolved from Protists that had flagella --->Chytrids are only Fungi retaining flagella

 Division Zygomycota  600 Zygomycetes  Mostly terrestrial ---> Live in Soil or decaying plant or animal material  Mycorrhizae- mutualistic associations with the roots of plants (Fig ; Pg. 585)  Black Bread Mold ( Rhizopus stolonifer ) is a common zygomycete  Hyphae spread out over food, penetrate it, and absorb nutrients  Bulbous Black Sporangia develop at the tip of the upright hyphae (Fig. 31.6; Pg. 578)  Hundreds of haploid spores develop and are dispersed throughout the air  Spores that land on moist food germinate  If food is used up the Rhizopus reproduce sexually (Fig. 31.6; Pg. 578)  The zygosporangia are resistant to freezing and drying and are metabolically inactive. When conditions approve haploid spores are released that colonize the new substrate.  Some zygomycetes can aim their spores. i.e. ---> Pilobolus

 Division Ascomycota  Over 600,000 species  Ascomycota- Sac Fungi  Live in Marine, Freshwater, and Terrestrial Habitats  Some of the most devastating Pathogens  ½ Live in symbiotic associations with algae called Lichens  Develop sexual spores in Saclike Asci.  Ascocarps ---> Macroscopic Fruiting bodies  Coidia ---> Naked spores

 Basidiomycota  Approximately 25,000 fungi, including mushrooms, shelf fungi, puffballs, and rusts are classified in the division Basidiomycota.  Basidium =A reproductive appendage that produces sexual spores on the gills of mushrooms / Latin for “little pedestal”  Club-like shape of Basidium gives rise to the common name club fungus  Basidiomycetes are important decomposers of wood and other plant material *includes: mycorrhiza (mutualistic associations of plant roots and fungi)-forming mutualists and plant parasites  Saprobic basidiomycetes are best at decomposing wood  Rusts and Smuts are particularly destructive plant parasites  Life cycle of a club fungus usually includes a long lived dikaryotic mycelium * mycelium (the densely branched network of hyphae [filaments that make up body of fungus] in a fungus) with two haploid nuclei per cell, one from each parent * mycelium reproduces sexual by producing elaborate fruiting bodies called basidiocarps (Mushrooms are one example) * A mushroom may release a billion basidiospores

 Molds are a type of fungus that grow rapidly and reproduce asexually  Myceli of these fungi grow as a saprobe or parasites on a variety of substrates  Early in life a mold produces asexual spores  Mold applies to only these asexual stages and later the same fungus may reproduce sexually, producing zygosporongia, ascocarps, or basidiocarps.  Unknown Molds: have no known sexual stages and are often referred to as deuteromycetes(imperfect fungi). *reproduce asexually by creating spores which they release  The most unusual fungi are predatory and trap and kill small protists/ animals(roundworms or nematodes)  Commercial Uses: *Pharmaceutical companies grow mold in large liquid cultures and extract antibiotics *Penicillin is produced by ascomycetes belonging to a species of Penicilium *Other Penicilium species are important fermenters on the surface of blue cheese, Brie and Camembert

 Yeasts  Yeasts are unicellular fungi that inhabit liquid or moist habitats, including plant sap and animal tissues  They reproduce asexually by simple cell division or by the pinching of small “bud cells” off a parent cell  Some yeasts reproduce sexually by forming asci or basidia, and are classified as Ascomycota or Basidiomycota  Humans have used yeast to raise bread and ferment alcoholic beverages for thousands of years, but only recently have they been separated into pure cultures for more controlled human use  The yeast saccharomyces cerevisiae, an ascomycete, is the most important of all human fungi  The tiny yeast cells are very active metabolically, and release small bubbles of CO2 that leaven bread  Cultured anaerobically in breweries and wineries, Saccharomyces ferments sugar to alcohol  Researchers also use it to study the molecular genetics of eukaryotes because it is easy to culture and manipulate.

 Lichens  A lichen is a symbiotic association of millions of photosynthetic microorganisms held together in a mesh of fungal hyphae  The fungal component is most commonly an ascomycete, but several basidiomycete lichens are known.  The photosynthetic partners are usually unicellular or filamentous green algae or cyanobacteria.  The merger of fungus and alga is so complete that lichens are actually given genus and species names, as though they were single organisms.  Mycorrhizae  Mycorrhizae are mutualistic associations of plant roots and fungi  The word mycorrhizae means “fungus roots” referring to the structures formed by both root cells and hyphae from the associated fungus  Mycorrhizae are extremely important in natural ecosystems and agriculture  Over 95% of all vascular plants have mycorrhizae  Half of all species of mushroom-forming basidiomycetes live as mycorrihizae with oak, birch, and pine trees