Fungi Lab

Tentative Phylogeny Fig 28.8

Generalized fungal lifecycle Spore-producing structures Spores ASEXUAL REPRODUCTION GERMINATION Zygote Mycelium GERMINATION MEIOSIS Spore-producing structures Spores Key Haploid (n) Heterokaryotic (unfused nuclei from different parents) Diploid (2n) PLASMOGAMY (fusion of cytoplasm) Heterokaryotic stage KARYOGAMY (fusion of nuclei) SEXUAL REPRODUCTION Zygote Mycelium

Phylogeny of fungi Chytrids Zygote fungi Arbuscular mycorrhizal fungi Sac fungi Club fungi Chytridiomycota Zygomycota Glomeromycota Ascomycota Basidiomycota

Fungal Divisions Chytridyomycota – Aquatic, with flagellated zoospores Diploid phase- sporophyte Zygomycota = zygospores. Resistant zygote sporangium Glomeromycota= zygospores arbuscular mycorrhizae. Ascomycota = ascospores Endogenous meiospores Basidiomycota = basidiospores Exogenous meiospores Deuteromycetes – imperfect, no sexual reproduction

Chytridiomycota Chytrids use an absorptive mode of nutrition and have chitin cell walls. There are a few unicellular chytrids, but most form ceonocytic hyphae. Chytrids share key enzymes and metabolic pathways with other fungal groups, but not with the slime molds Ancestral to other three groups on land Forms flagellated zoospores

Allomyces Life cycle #13 #14 Diploid Haploid

Allomyces gametophyte (n) slide

Gametophyte

Sporophyte Meiosporangia

Allomyces (2n) Fresh Sample

Fungal Divisions Chytridyomycota – Aquatic, with flagellated zoospores Diploid phase- sporophyte Zygomycota = zygospores. Resistant zygote sporangium Glomeromycota= zygospores arbuscular mycorrhizae. Ascomycota = ascospores Endogenous meiospores Basidiomycota = basidiospores Exogenous meiospores Deuteromycetes – imperfect, no sexual reproduction

Zygomycete lifecycle #16 #15

Zygosporangium formation +, - suspensor hyphae grow together. Each tip cuts off a gametangia with complete septa. Gametangia fuse into one large heterokaryont. Nuclei pair up form many diploid nuclei. Resistant wall forms on Zygosporangium Before germination meiosis takes place Forms sporangia, releasing haploid spores

Asexual Spore formation Haploid nuclei migrate to swollen hyphal tip. Hyphal tip forms complete septum, now a sporangium. Each nucleus forms a spore around itself with cytoplasm, endospores. Sporangium wall breaks. Spores blow away.

Phycomyces suspensors

Phycomyces on low power Zygosporangia

Phycomyces Gametangia fusing

Pilobolus Sporangium with mitospores Swollen sprangiophore

Spore dispersal

Positive Phototropism

Fungal Divisions Chytridyomycota – Aquatic, with flagellated zoospores Diploid phase- sporophyte Zygomycota = zygospores. Resistant zygote sporangium Glomeromycota= zygospores arbuscular mycorrhizae. Ascomycota = ascospores Endogenous meiospores Basidiomycota = basidiospores Exogenous meiospores Deuteromycetes – imperfect, no sexual reproduction

Mycologists have described over 60,000 species of ascomycetes, or sac fungi. They range in size and complexity from unicellular yeasts to elaborate cup fungi and morels. Ascomycota: Sac fungi produce sexual spores in saclike asci

Ascomycetes are characterized by an extensive heterokaryotic stage during the formation of ascocarps. Fig

Ascus formation Hyphal tip makes complete septum, Nuclei fuse – a single 2n nucleus Meiosis – 4 haploid nuclei One mitotic division – 8 haploid nuclei Each nucleus cuts off some cytoplasm and forms new wall, inside original hyphae wall. 8 ascospores are forcibly ejected by osmotic pressure. Different forms of ascocarp have evolved.

Ascospore formation Zygote Meiosis Mitosis Spore wall N+N

Peziza sp. apothecia

Apothecia- #18

Asci – Slide #18

Morchella sp.

Morchella x-section

Morchella slide

Sordaria- perithecia

Sordaria slide #

Fresh Sordaria slide

Saccharomyces cervisea Budding

Conidia Many Ascomycetes reproduce asexually by producing enormous numbers of Conidia, asexual spores, (exogenous mitospores) which are usually dispersed by the wind. Conidiophore continuously divides forming more spores at tip.

Fungal Divisions Chytridyomycota – Aquatic, with flagellated zoospores Diploid phase- sporophyte Zygomycota = zygospores. Resistant zygote sporangium Glomeromycota= zygospores arbuscular mycorrhizae. Ascomycota = ascospores Endogenous meiospores Basidiomycota = basidiospores Exogenous meiospores Deuteromycetes – imperfect, no sexual reproduction

Basidiomycota Typical Mushroom Almost no asexual reproduction Many mycorrhizae species Oldest organism ? Mushrooms caps have basidia on gills. The spores drop beneath the cap and are blown away.

The life cycle of a Basidiomycete usually includes a long-lived dikaryotic mycelium. Fig

Basidia formation

Coprinus

Basidiospores

Lichens Symbiosis of –Phycobiont, algae / cyanobacteria –Mycobiont - fungi. Not individual organisms Primary colonizers of new land in succession, and in tundra areas Soredia asexually reproduce lichen –Fungi often reproduce on their own. Lichen acids, dyes

Fig

Three growth forms: 1.Crustose – flat on stones 2.Foliose- leaf-like as in picture 3.Fruticose- upright growing Phycobiont in inner layers protected by fungi on top and bottom

(a) A fruticose (shrub-like) lichen (b) A foliose (leaf-like) lichen (c) Crustose (crust-like) lichens

Physcia # 28 Ascocarp Phycobiont

Umbilicaria sp. Upper Cortex Phycobiont layer Filamentous Hyphal layer medulla Lower Cortex

Glomeromycota Has some characteristics similar to zygomycetes. DNA comparisons show then to be their own group Form Arbscular endomycorrhizae

Endotropic Mycorrhizae

Arbuscular mycorrhizae 2.5  m Plant cell wall