HORT 1217

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HORT 1217

• Kingdom Protista
• Kingdom Fungi

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The Five Kingdoms
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What are protists?

• Simplest of the eukaryotes.
• Protists organisms that were put together
  because they don't really seem to belong to any
  other group.
• Some protists perform photosynthesis like plants
  while others move around and act like animals,
  but protists are neither plants nor animals.
• They're not fungi either.

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What are protists?

• All protists are (supposed to be)
• eukaryotic and
• unicellular. While they are all eukaryotic, they
  aren't all unicellular. The algae in particular
  often occur in multicellular forms. Most of these
  are quite small, but some get to be rather large
  such as seaweed and kelp.
• they all have swimming spore stages.
• They are often placed into three groups based on
  their method of obtaining energy.

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3 Types of Protists

• Absorptive
• Fungus-like protists absorb food from their
  surroundings.
• Photosynthetic
• Plant-like protists (algae).
• Engulfing
• Animal-like protists (protozoa) eat, ie.
  engulf, food particles
• Difficult to determine an accurate phylogeny
  because some, like the genus Euglena, both eat
  AND photosynthesize.

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Examples of Protists

• Fungus-like protists known as slime molds are
  fascinating organisms, often studied for their
  unusual life cycle.

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Examples of Protists

• Microscopic algae (plankton) form the base of
  aquatic food chains, assuming the role that green
  plants play on land.

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Examples of Protists

• Protozoa are important parts of plankton
  communities and good scavengers.

Paramecium
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Algae Chlorophyta (green)

• Most important component in plankton, base of the
  food chain
• Complicated life cycles with alternation of
  generation
• Specialized cells
• Akinetes for asexual reproduction
• Heterocysts for nitrogen fixation
• Most common members of symbionism in lichens
  (fungi algae)

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Algae Chromophyta(yellow-green)

• Yellow green, golden-brown, brown
• Brown algae (kelp), algin, thickening for
  toothpaste, gelatin-like material
• Diatoms
• single cells with silica cell walls
• Important food sourcefor detritus feeders

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Diatoms
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Some Kelps (Brown Algae)
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Algae Rhodophyta (red)

• Red pigment for photosynthesis
• Warmer waters, but there are a few species that
  you can find here
• Nori used in sushi

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Algae Euglenophyta

• Euglenoids, photosynthetic
• Facultative autotrophs
• Live in fresh water, may form a green scum on
  water surface
• Mobile by flagella

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Algae Dinophyta

• The dinoflagellates
• Cause red tide, poisonous waters that make shell
  fish toxic to humans

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Protists Phylum Myxomycota

• Not of great economic significance
• However, some important plant disease are caused
  by slime molds and are significant in ecosystems
  as decomposing organisms
• Slime molds perch onthings like turfgrass

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Protists Phylum Oomycota

• Coenocytic mycelium cellulose-type cell wall
• Alternation of generations
• Fast growth in wet ecosystems Water mold
• Colonizers that are quickly displaced by other
  higher organisms in ecological succession
• This group includes several important
  disease-causing organisms
• Pythium damping off in many seedlings
• Phytophthora Irish Potato famine (blight)
• Saprolegnia common fish fungus (cotton wool)
• Downy mildew grape, lettuce, corn, cabbage

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Oomycota Not True Fungi

• Oomycetes dont have chitin cell walls they have
  cellulose-type cell walls.
• Mostly coenocytic primitive feature
• Vegetative hyphae of oomycetes have diploid
  nuclei (true fungi haploid)
• Flagellar chemistry differences

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Life cycle ofSaprolegnia

• alternation of generations
• Gametes always haploid
• unite to form a zygotealways diploid
• Zoospores are motile

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Life cycle ofPythium
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Downy mildew of GrapesCaused by Plasmopara
viticola
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Protists Pathology

• Overwintering
• Overwinter in protective oospore
• Ensures long-term survival
• Primary Inoculum
• Oospore germinates into infection thread, or
  produces zoospores directly
• Hyphae penetrate intercellular spaces

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Protists Pathology

• Secondary spread (inoculum)
• Zoospores from sporangia
• Entry
• Enter directly between cells with enzymes
• Pathology
• Kill cell with toxins and enzymes

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Protists Control options

• Host
• Resistance
• Avoid stress
• water stress
• fertilizer salt stress
• Environment
• Soil environment
• Avoid overhead watering and wet leaves

• Pathogen
• Chemicals
• Exclude
• foot baths
• washing machinery
• sterilization
• sanitation
• Quarantines

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Kingdom Fungi
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Kingdom Fungi

• True fungi (as opposed to the water molds)
• Filamentous organisms that reproduce via spores
• Fungi are hidden we often only see their
  fruiting structures (mushrooms, spore-ooze)
• Cell walls made of chitin (no chlorophyll or
  cellulose)
• Feed by absorbing nutrients from organic material
• Hyphae secrete acids and enzymes that break the
  surrounding organic material down into simple
  molecules
• Taxonomy based on reproductive stages the same
  organism can have two names
• Teleomorph sexual stage (Nectria haematococca)
• Anamorph asexual stage (Fusarium solani)

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Uses of Fungi

• Break down dead organic material (great
  decomposers)
• Form mycorrhizae to help most vascular plant
  roots absorb essential nutrients
• Provide drugs (penicillin other antibiotics)
• Foods (mushrooms, truffles and morels, making
  bread, champagne, and beer)
• Plant and animal diseases
• in humans, ringworm, athlete's foot, etc.
• in plants, rusts, smuts, and leaf, root, and stem
  rots
• Model organisms for study (eg. Yeasts)

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Fungi Nutrients

• Saprophytic fungi
• Live on dead organic matter decomposers
• Obligate parasites
• Only grow on living hosts (usually plants)
• Facultative saprophytes
• Usually parasitic, but can live saprophytically
• Facultative parasites
• Usually saprophytic, but can be parasitic when
  living hosts are available

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Fungi Phylum Chytridiomycota

• The chytrids early fungi
• Some are freshwater, some marine
• Some parasitic, while others live on decaying
  plants and insect parts.
• Some are unicellular, some coenocytic, and others
  produce mycelium
• Few have any noticeable impact on humans, with
  the exceptionpotato wart (Synchytriumendoboticum
  ), and those usedin experimental research(e.g.
  Allomyces).

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Fungi Phylum Zygomycota

• Coenocytic fungi
• Reproduce sexually by thephysical fusion of
  gametangiato form a zygosporangium.
• Also reproduce asexually via spores
• Includes the common bread mold (Rhizopus) and
  fruit soft-rots (Mucor, etc)
• Insect pathogens too
• Entomophthora muscae infectsand kills houseflies
• Dung fungus (Pilobolus)

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Fungi Phylum Ascomycota

• Narrower hyphae than previous groups septate
  allows them to explore more niches (drier, etc.)
• Form mycorrhizae with tree roots
• Sexual structures in a sac (ascus w 8 spores)
• Four types of ascoma (ascus houses)
• See pathology supplement (pg 33-34)
• Asexual spores conidia
• Includes Morels

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Fungi Phylum Basidiomycota

• Mushroom fungi (incl. Truffles)
• Form mycorrhizae with tree roots
• Sexual structures on a basidium (club-shape)
• Asexual spores conidia (not as common)
• Important plant pathogens
• eg. White pine blister rust

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Fungi Phylum Deuteromycota

• Fungi Imperfecti
• Fungi for which sexual structures have not been
  discovered yet
• Container group for organisms until they can be
  matched to other named organisms
• They have the same asexual reproductive
  structures as the ascomycetes

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Lichens

• Mutualistic symbioses of algae and fungi
• Colonize severe environments
• Body is called a thallus
• Crustose
• Foliose
• Fruticose