1Kingdom Fungi2Characteristics of FungiHeterotrophic saprobes – cells of hyphae secrete digestive enzymes and absorb products of digestionCell wall made of chitin - a polysaccharide with addednitrogen groupHypha - filamentous body - forming mycelial mat - each hypha is composed of a chain of cells withor without separating septa3Nuclear mitosis - all stages of mitosis go on within the nucleus - followed by nuclear division and then cell divisionSome fungi have a dikaryon stage - cells of two different hyphae fuse and the nuclei of each remain distinct within the new hypha4• Differ from most animals and plants in that eachcompartment of hypha can contain one, two or morenuclei– monokaryotic - each compartment has a single nucleus– dikaryotic - two distinct nuclei within each hyphalcompartment• Possible for many nuclei to intermingle in commoncytoplasm of fungal mycelium which can lack distinctcells– heterokaryotic – dikaryotic or multinucleate hypha hasnuclei from genetically distinct individuals– homokaryotic – hyphae whose nuclei are geneticallysimilar to one anotherReproduction in Fungi5Fungi have both asexual and sexual reproductionAsexual -• fragmentation (breakage) of hyphae can produce newmycelium• production of spores by modified hyphae - sporesdispersed by windSexual -always involves fusion of cells from differentmating types (+/-)in some, the cells that fuse are gametes, in othersthe cells that fuse are part of hyphaein some, fusion produces a diploid zygote, in othersthe fusion produces a dikaryon, or heterokaryonfusion of nuclei within dikaryon producesdiploid zygote nucleusmeiosis of zygote produces haploid spores6N2Ngametesmeiosis72NNNmeiosis8meiosisdikaryonnuclear fusionNN+N2N9There are four major groups of fungiChytridiomycotaZygomycotaBasidiomycotaAscomycota10Phylum Chytridiomycota - 1000 speciesaquatic, flagellated fungi– most closely related to ancestorsof all fungi– gametes are flagellated– has well developed sporophyte(diploid) stage11e.g. Allomyces - sporic meiosis with multicellular haploid stage(gametophyte) and multicellular diploid stage (sporophyte)12Phylum Zygomycota – 1050 species Bread molds and relatives Sexual and asexual reproduction common Hyphae without septa, except for separation of reproductive structures Has short diploid stage(zygosporangium)13e.g. Rhizopus - zygotic meiosis - multicellular haploid stageonly14Phylum Basidiomycota – 22,000 species mushrooms, toadstools, rusts, smuts many species eatenmany poisonous or semi-poisonous specieshas well developed dikaryotic stagethe basidiocarp (mushroom)carries basidia on gills or inporesnuclei fuse within basidiaand then producebasidiospores by meiosis151617Phylum Ascomycota – 45,000 species – Most yeasts, truffles, morels Great diversity - includes many plant parasites –e.g. Dutch elm disease and chestnut blightSometimes called cup fungi because of the shapeof their reproductive structuresHas well developeddikaryotic stageThe ascocarp carries asciwithin cupsNuclear fusion occurs withinascus, meiosis followsproducing ascosporesSome species lack a sexualstage (e.g. Penicillium)181920•Yeasts– unicellular - most reproduction is asexual and takesplace by cell fission or budding• ferment carbohydrates - produce ethanol as byproduct• play a leading role in genetic research21Ecology of Fungi• Fungi are saprobes - heterotrophs that secretedigestive enzymes and absorb products ofdigestion.• some are important decomposers can digest lignin and cellulose of wood• some are parasitic on living organismsathlete’s foot, ringworm, corn smut, rusts22•some are predatory - some can anesthetize and consume roundworms (our local oyster mushroom)•some have mutualistic relationships with other organismslichen = fungus + green alga fungus provides alga with some nutrients needed for photosynthesis - alga provides complex organic nutrients to fungusmicorhizzal fungi - associate with plant roots and absorb nutrients from soil to aid plant23Fungus is usually ascomyceteSpecialized hyphae penetratephotosynthetic cells andtransfer nutrients.Lichens are able to invadeharsh terrains and climates.They are extremely sensitiveto pollutants24About 90% of all kinds of vascular plants are involved inmutualistic symbiotic relationships (mycorrhizae).Fungi are able to extract raw nutrients from soil that plants can’tarbuscular mycorrhizae - fungal hyphae penetrate outer cellsof plant rootectomycorrhizae - hyphae surround, but do not penetrate, cellwalls of roots2526•A range of mutualistic fungal-animal symbioses has been identified.• ruminants• leaf-cutter ants• termites27Chytridiomycosis - emergent infectious disease in amphibianschytrid Batrachochytrium dendrobatidisAflatoxins - carcinogeniccompounds produced bystrains of Aspergillus flavusgrows on corn, peanuts,cotton