2Answer these questions: How do fungi differ from other organisms?How does the lifestyle of a fungus enable it to obtain food?What factors make each phylum of fungi distinctive?How do fungi affect humans?
3Look at page 406 of your textbook What do you see in the main picture on this page?Read the caption. What is really shown in the picture?Are “fungus flowers” made of fungus?Why would a fungus go to all the trouble of making a plant imitate a flower?
4Page 406 continuedDo you think this fungus hurts or helps the rock cress plant?Would you guess that fungi could flower on its own?
5Characteristics of Fungi Cell structureLifestyleFood acquisitionHabitatCell walls
7Other characteristics of Fungi HeterotrophsDigest food outside its body by secreted enzymes then absorb the nutrientsTypically terrestrialKey decomposers of plant materialMost derive their nutrition from plantsCell walls made of chitin
12Hyphae The dominant structure of fungi Long, multinucleated, typically multicelled, one-cell thick fungal tissueTypically hidden from sight since fungi grow their hyphae into their foodServe as vascular channels along which nutrients are passed
24ReproductionAll nuclei are haploid except for zygote nuclei (except some Chytridiomycota)In the sexual reproduction, hyphae of two different mating strains meet and fuse but the two types of nuclei may coexist without fusion for most of the life of the fungusFungi reproduce by relasin spores
25Reproduction Monokaryotic compartment has a single nucleus Dikaryotic compartment has two genetically distinct nucleiHeterokaryotic hyphae have two kinds of genetically different nucleiHomokaryotic hyphae have genetically similar nuclei
36Zygomycota Non-reproductive hyphae lack septa Include the common bread moldsProduce zygospores
37Life Cycle and Sexual Reproduction Sexual reproduction is via fusion of multinucleate gametangiaMay occur between same or different mating typesMassive, haploid zygospore forms around diploid zygote nucleiMeisois occurs during germination
53Sexual Reproduction Ascogonia are female, have trichogyne Antheridia are male, fuse with trichogyneMale nuclei travel to ascogonium to pair with opposite nucleiHeterokaryotic hyphae arise from point of fusionAn ascus containing two nuclei forms at the hyphal tip
54Sexual ReproductionNuclei within the ascus fuse, forming diploid zygote which immediately undergoes meiosisFour haploid daughter nuclei are the result.These haploid daughter nuclei undergo mitosis to form 8 ascosporesThe ascospores are then released, in most cases by the ascus bursting.
55Asexual ReproductionConidia are produced at the ends of conidiophores. Conidiophores are the stalk-like vertical growths on the hyphae. Spores are formed at the end of the conidiophores and are separated by septum and are called conidia.The spores are released and then germinate
67BasidiomycotaCharacteristic reproductive structure is called a basidium.Syngamy occurs within basidiumMeiosis occurs immediately, forming four haploid basidiosporesFour basidiospores are borne on one basidium
69Sexual Reproduction Spore germinates forming homokaryotic hyphae Eventually septa form between nuclei of primary myceliumDikaryotic, heterokaryotic secondary mycelium forms when hyphae of different mating types fuseBasidiocarps form of completely dikaryotic hyphaeBasidia line the gills of typical mushrooms
70DeuteromycotaCommonly called Fungi Imperfecti because they exhibit only asexual reproductionMostly ascomycetes, few zygomycetes and basidiomycetesMany are human and plant pathogensOthers produce important chemicals such as penicillin
71ParasexualityParasexuality occurs when two different hyphae fuse forming heterokaryotic hyphae. The two different nuclei may exchange portions of chromosomes between nuclei.Provides a certain amount of genetic recombination.
73Lichens Mostly ascomycetes with green algae and/or cyanobacterium Specialized hyphae penetrate or envelop photosynthetic cellsFungal chemical signals direct photosynthetic metabolismCould be considered a form of controlled parasitism
74LichensReproduction of the fungal portion is via normal fungal sexual reproductionReproduction of the photosynthetic component is asexualThe lichen as a whole can fragment and be transported by wind… to a new location to form a new individual
75Lichens Can inhabit cold, dry, generally harsh environments Help break rock surfaces and prepare habitat for other organismsColoration of lichen protects photosynthetic partnerCan survive adverse conditions by nearly halting metabolism
81Mycorrhizae Most plant roots associated with certain fungi Fungus aid in transfer of soil nutrients into rootsPlant provides organic carbon to fungusArbuscular mycorrhizae and ectomycorrhizae
82Arbuscular Mycorrhizae Hyphae penetrate outer cells of rootMore common mycorrhizae, generally a zygomycetesMay increase yield of crops with less energy input
83Ectomycorrhizae Hyphae surround, but do not penetrate roots Less common, mostly basidiomycetes, some ascomycetesCharacteristic symbiont of shrubs and trees
84Advantages Plants more resistant to drought, cold and harsh conditions May provide better protection against acid precipitationPrevent accumulation of toxic metalsSpeed germination of orchid seedsProvide better growth in poor soils