Fungi

Kingdom Fungi

  • Overview: Fungi are essential to ecosystems, connecting various biological systems globally.
    • Prefix "MYCO" refers to fungi.
    • Eukaryotic and heterotrophic.
  • Nutrition: Fungi secrete enzymes for external digestion, subsequently absorbing nutrients.
    • Composition: Composed of chitin (similar to cellulose in plants) in their cell walls.

Feeding Strategies of Fungi

  • Saprobes:
    • Decomposers that absorb nutrients from dead organisms and organic matter, returning nutrients to the ecosystem.
  • Parasites:
    • Feed on living organisms; some fungi can be harmful to plants.
  • Hyphae Structure:
    • Composed of filaments called hyphae, which create a network known as mycelium.
    • Extends into food sources, increasing surface area for enzyme secretion and nutrient absorption.
    • Example: Mold on bread
  • Connection to Plants:
    • Fungi create networks that link plant root systems, enhancing productivity (e.g., through no-till farming).
  • Human Diseases: Examples include ringworm, athlete's foot, valley fever, and histoplasmosis.

Classification of Fungi

  • Main Phyla: Three primary phyla of fungi.
Phylum Zygomycota (Zygote Fungi)
  • Characteristics: Produces zygospores during sexual reproduction.
    • Example: Rhizopus nigricans (black mold)
  • Reproduction Processes:
    • Sexual Reproduction:
    1. Hyphae of compatible types fuse.
    2. Zygosporangium forms; nuclei fuse into diploid.
    3. Meiosis occurs to produce haploid spores.
    • Asexual Reproduction:
    1. Spores produced via mitosis.
    2. Sporangium emerges from hyphae, releasing genetically identical spores.
Phylum Ascomycota (Sac Fungi)
  • Characteristics: Produces ascospores; the largest group of fungi.
    • Examples: Truffles, morels
  • Reproduction Processes:
    • Sexual Reproduction:
    1. Two hyphae fuse, forming an ascogonium.
    2. Develops dikaryotic hyphae.
    3. Ascus produces haploid ascospores.
    • Asexual Reproduction:
    • Forms conidia (spores).
Phylum Basidiomycota (Club Fungi)
  • Characteristics: Produces basidiospores; includes mushrooms.
  • Reproductive Structures:
    • Basidiocarp is the visible mushroom.
  • Sexual Reproduction:
    • Basidia produce haploid basidiospores through meiosis.
Phylum Deuteromycota (Imperfect Fungi)
  • Characteristics: Lacks a known sexual reproductive stage; primarily reproduce asexually.
  • Example Genera: Penicillium and Aspergillus produce conidia via asexual reproduction.

Yeasts

  • Characteristics: Single-celled fungi, classified in Ascomycota.
  • Reproduction:
    • Asexual reproduction occurs through budding (new cell forms by pinching off from the parent).
  • Economic Importance: Essential for alcohol production and baking.

Mycorrhizae

  • Definition: A mutualistic relationship between fungi and plant roots.
  • Function:
    • Fungi absorb nutrients and water from the soil, transferring them to plant roots.
    • Plants supply fungi with sugars produced during photosynthesis.

Lichens

  • Structure: The body of lichens is called a thallus.
  • Types of Lichens:
    • Foliose: Leafy, lives on trees.
    • Crustose: Crusty, found on rocks.
    • Fruticose: Tumbleweed-like, inhabits trees.