Chapter 31 – Introduction to Fungi

Fungi characteristics Heterotrophic External digestion Hyphae –Threadlike filaments –Chains of cells can be separated by cross walls pores –Some fungi lack cross walls, and have many nuclei within large mass of cytoplasm

Fungal structure Hyphae branch repeatedly to form mycelia Mushroom Fast growth –Longer but not thicker

Fungal life cycle Many species can reproduce sexually and asexually Haploid spores transported by water or wind Sexual reproduction –2 haploid mycelia of different mating types grow towards each other and fuse Heterokaryotic (n + n)

Fungal life cycle cont Asexual reproduction –Mold Produce spores on tips of specialized hyphae –Yeast Budding

Fungal groups Sexual reproductive structures often used to classify –Imperfect fungi – no known sexual stage All but one group lack flagella –Evolved from flagellated ancestor

Fungal groups cont Chytrids Zygomycetes or zygote fungus Glomeromycetes Ascomycetes or sac fungus Basidiomycetes or club fungus

Chytrids Only fungi with flagellated spores Earliest line of fungi Lakes, ponds, soil Decomposers or parasitic

Zygomycetes Fast growing molds Asexual reproduction when food is abundant; sexual when scarce Zygosporangium formed from fused mycelia –Tolerate dry/harsh environment

Glomeromycetes Form distinct type of mycorrhizae –Symbiotic relationship with plant roots –Invade plant root and branch into treelike structures (arbuscles)

Ascomycetes Saclike structures called asci produce spores –Sexual reproduction when harsh environment Unicellular yeast, morels, cup fungus Lichen –Symbiotic relationship with cyanobacteria or algae

Basidiomycetes Mushrooms, puffballs, shelf fungus / plant parasites rusts and smuts Club shaped, spore producing structure called basidium

Parasitic fungi Corn smut Ergot Mycosis –Mild to systemic –Opportunistic

Benefits of fungi Mutualistic symbiotic relationships Essential decomposers –Organic matter, petroleum products, toxic chemicals Food products Medicinal value –Antibiotics (penicillin the first) Laboratory work