ppth 104 second exam

• General understanding of Fungi

  • heterotrophic organisms – cannot produce their own food

  • with a hyphal structure – thread-like structure of Fungi

  • obtains nutrients by absorption – mainly through its mycelia or other specialized structures such as haustorium
• Life styles of Fungi

  • Saprobic – lives on rotting hosts or dead organic matter

  • Parasitic – attacks living organisms and absorbs their nutrients

  • Mutualistic – host and fungi benefit from each other
• Microfungi

  • Fruiting bodies are microscopic

  • Includes molds, mildews, rusts, smuts, etc
• Macrofungi

  • Fruiting bodies are visible with the naked eye

  • Includes mushrooms, puffballs, polypores, etc.
• 1753 - Fungi recognized as a separate kingdom
• 1821 - treatment of the known fungi started
• 1851 - pleomorphism in fungi recognized
• 1870 - asexual fungi classified separately
• 1910 - category of special forms introduced
• 1912 - separate naming of morphs allowed
• 1931 - keys to all known fungal genera
• 1935 - latin description mandatory
• 1990 - rDNA fungal primers introduced
• 2000 - Phylogenetic species recognition
• 2001 - oomycota placed in kingdom straminipila
• 2004 -mycobank
• 2006 - phylogenomics
• 2011 - separate naming of morphs ended
• 2014 - reference sequences for higher taxa issued
• The Kingdom Fungi

  • Distinct from the Kingdoms Plantae and Animalia

  • Closer relationship to Animalia

  • Comprises fungi with septate hyphae, except the zoosporic Chytridiomycota and coenocytic Zygomycota

  • Formerly summarized as the “Higher Fungi”

  • The informal grouping of “Lower Fungi” includes several protists, protozoa, and stramenopiles
• How to Study Fungi?

  1. A cursory observation with the low power of the microscope or stereomicroscope 
  2. Detailed study of the squash mounts or sections 
  3. Preparations of an accurate description with drawings and photos
  4. Obtaining a pure culture if possible, deriving a DNA sequence
  5. Consultation of the literature for identification
• • Common staining chemicals:
  • Lactophenol 
  • Lactophenol cotton blue
  • Potassium hydroxide (KOH) 
  • Slide preparation 
  • Mounting of spores (light scraping) 
  • Cross sections or squash mounts (cutting off thinly using a sharp blade or torn a strip using needle-nosed tweezers)
• Hierarchy of Ranks 

  • Division: -mycota 
  • Subdivision: -mycotina
  • Class: -mycetes 
  • Subclass: -mycetidae 
  • Order: -ales
  • Family: -aceae 
• The species is the basic unit of taxonomy
• Phenotypic Species Concept

  • Particularly about morphology but also involves physiological features strongly affected by environmental conditions 
  • Highly variable 
  • Valuable for a first sorting of taxonomic classification 
  • Chemical features are also an expression of the phenotype so it is considered under this concept 
  • particularly used in yeast taxonomy
• Biological Species Concept

  • It comes after the ancestors of an organism have become separated by barriers of genetic exchange, such as geographical location and certain conditions 
  • Conspecificity (being membrane of the same species) is generally regarded to be indicated by compatibility or interfertility 
• Phylogenetic Species Concept 

  • Based on DNA analysis 
  • Allows a very accurate and reproducible grouping of individuals at various levels
• Chytridiomycota


  A very ancient group of fungi, previously thought as protists
• Chytrids


  Another name for the Chytridiomycota division
• Chytridiomycota


  • Water- or soil-inhabiting fungi
  • Mostly saprobic or free-living
  • Can degrade chitin and keratin
  • Many parasitize and destroy algae which form a link in a food chain of aquatic animals
  • Lives within the host cells as parasites
  • Lacks true mycelium; if present, mycelium is round or elongated
  • Forms coenocytic thallus as vegetative structure
  • Have zoospores with a single posterior flagellum
  • Ultrastructural characters of zoospores are the basis of segregating one order from the other
  • The microtubular substructure of the flagella is an ancestral quality that is found in cilia of some protists, lower plants and animals
• Sexual reproduction in fungi involves the union of two compatible nuclei
• Plasmogamy and karyogamy results in the formation of resting sporangium

  • Sporangium is thickened, often pigmented and/or ornamented wall
• • Planogametic copulation
  • Isogamous planogametes - male and female gametes are identical in morphology (ex. Catenaria)
  • Anisogamous planogametes - male and female gametes are morphologically similar but different in terms of size and shape (ex. Allomyces)
  • Heterogametic planogametes - motile male enters the non-motile oogonium and fertilizes the egg (ex. Monoblepharella)
• • Gametangial copulation - forms structures that functions as gametangia such as in Oomycota and Rhizophydium of Chytridiomycota
  • Somatogamy - common especially in higher fungi where no sex organs or structure are formed but the somatic cells
• Asexual Reproduction 

  • Chytrid zoospores are microscopic, uninucleate, unicellular, and uniflagellate
  • Lacks cell wall
  • Chytrids were initially the only group in Kingdom Fungi that produce zoospores
  • Zoospores do not feed; relies only on endogenous energy reserves
• • Two types of flagella:
  • Whiplash
  • Smooth, usually directed backwards, propels the zoospore
  • Tinsel
  • With tripartite hairs (mastigonemes); directed forward, pulls the zoospore
• kinetosome – the basal body of the zoospore where flagellum is attached
• • All zoospores have two kinetosomes, but if only one flagellum is formed, the second kinetosome is non-functional
• Kinetosome - Basically a modified or flagellated centriole; highly conserved structure composed of 9 triplets of microtubules arranged in a cartwheel manner
• Single posterior whiplash flagellum - Chytridiomycota

  Several posterior whiplash flagella - Neocallimastigales

  Biflagellate zoospore with two whiplash flagella of unequal size - Myxomycota and Plasmodiophoromycota

  Zoospore with single anterior flagellum of tinsel type - Hypochytriomycetes

  Biflagellate zoospores with both anterior and tinsel type flagella - oomycota

  Biflagellate zoospores with anterior tinsel flagellum and posterior located whiplash type flagellum - oomycota