Ch 19 - Fungi

1. Ch 19 - Fungi

2. Fungi • Eukaryotic heterotrophs • Most saprotrophs, some parasitic

3. Important Decomposers • All release digestive enzymes onto the dead or dying organic matter, then absorb the nutrients through their hyphae –called external digestion • This speeds up the recycling of nutrients

4. Typical Structure • Hyphae: tiny filaments with or without cross-walls • Can be multinucleate • Most have haploid nuclei in their hyphae • Most of the life of a fungi is spent as haploid hyphae

6. Hyphae

7. Mycelium: tangled masses of hyphae • Often underground • High surface area for absorption of nutrients • Often the mycelium is the largest part of the fungi

8. Fungi- Complicated Life Cycles • Most fungi have both asexual and sexual reproduction • We will study the life cycle of the common mushroom, a club fungus

9. Asexual • Some hyphae will become sporangiophore – sporangia producing structures. • The sporangia produce haploid spores • The spores are distributed by the wind and will produce new hyphae and mycelium

12. Sexual Reproduction • Hyphae are two equal but opposite mating types: (+) and (-). (instead of male and female) • (+) and (-) hyphae meet and each will form a gametangium (gamete forming structure) • The two gametangia fuse and some produce a fruiting body • At some point, the haploid nuclei will fuse, but they usually quickly divide again by meiosis to make haploid spores again. • The spores are distributed as in asexual reproduction

14. Sexual reproduction is undertaken to mix up the gene pool for increased variation in the species.

15. 5 Phyla • Classified by their reproductive types and their structure

16. 1. Oomycota – Water Molds • Closely related to plant-like protists • Cause white fuzz on organic matter sitting in water and some diseases (ex. Potato blight) • Produce spores that swim through water to new food sources

17. Potato Blight  Water Molds 

18. 2. Zygomycota – Common Molds • Ex. Black bread mold • Have rhizoids: hyphae that penetrate the food • Act as roots – anchors the mold, releases the digestive enzymes and absorbs the nutrients Rhizoids 

19. Have Stolons: act like runners – grow across the surface to new hyphae and rhizoids • Also have Sporangiophores – stalks that grow above the surface and produce sporangia Stolon 

20. Sporangia Sporangiophore

21. Sporangia produce up to 40,000 spores that will germinate when conditions are optimal (warm and moist)

23. Spores (N)  Spores (N)  ASEXUAL (-) (+)  sporangiophore SEXUAL Gametangia meiosis Zygospore (2N)

27. 3. Ascomycota: Sac Fungi • Largest phylum of fungi • Include yeasts (unicellular) and morels (edible)

28. Sac fungi produce very fine spores called conidia (means dust) • Their fruiting bodies are usually the largest visible part of the fungi Condia 

30. 4. Basidiomycota – Club Fungi • Includes the common mushroom, shelf (bracket) fungus, puffballs, toadstools, jelly fungi, and rusts (plant parasite)

34. Jelly Fungus

35. Bracket Fungus

37. Coral Fungus

38. Coral Fungus

40. Jelly Fungus

41. Coral Fungus

47. Rusts

49. The secondary mycelium can produce a fruiting body overnight if the conditions are right. • Cytoplasm from cells in the mycelium stream into the growing mushroom to help it grow faster.