quiz 9 Flashcards
(44 cards)
Major classes within the Pezizomycotina
Sordariomycetes
Sordariomycetes- morphological traits
- perithecial ascomata
- (flask-shaped with a pore that releases spores)
- form on or in a stroma - ~fusion~ between distinct gametangia
- hermaphroditic with few female traits
- “female traits”- ascogonium production
- different from mating types
Sordariomycetes- what distinguishes them from other classes?
- diverse anamorphs
- major group of plant pathogens and endophytes (economically important)
- many produce toxins, also making them economically important
how many taxonomic groupings of Sordariomycetes are we learning?
six orders within three subclasses
Gametangia of Sordariomycetes
spermatia (male gametes)
- essentially conidia on an antheridia (which is like a conidiophore)
- ASEXUAL
ascogonia or protoperithecia
- with trichogynes
- SEXUAL- occurs at the same time as asexual stages
the three major subclasses within the Sordariomycetes
Sordariomycetidae
Hypocreomycetidae
Sordariomycetidae- characteristics
- perithecial (flask-shaped) ascomata with colors that range light to dark
- Stroma producing the perithecium: small or non-existent
Four major orders of subclass Sordariomycetidae
Sordariales
Diaporthales
Ophiostomales
Magnaporthales
Sordariales characteristics
- generally saprophytic
- habitat: wood, dung, other saprophytes
- ascospores dark w appendages
- asci w distinct apical ring
Diaporthales
- plant parasites
- stromatic ascomata with long perithecial necks (unlike the rest of the groups of sordariomycetidae)
Ophiostomales
- long perithecial with long necks OR
- prototunicate asci
- associated w insects
Magnaporthales
- sexual stage almost never seen (asexual stage allows spread of disease to happen very quickly)
- infect grasses, rice, turf
- necrotrophic
- infects leaves via penetration of appresorium
- turgid pressure helps it punch thru the leaf
Name the pathogen responsible for Chestnut Blight. Provide its taxonomic grouping (order, subclass and class)
- Cryphonectria parasitica
- class sordariomycetes, subclass sordariomycetidae, order diaporthales
describe/illustrate & label the major components of the asexual and sexual stages of Cryphonectria parasitica
kills phloem cells, clogs xylem, erupts thru bark on cankers
- sexual: perithecia from stroma
- asexual: pycnidia (look very similar to perithecia but produce conidia instead of ascospores)
Describe hypovirulence and how it’s applied to Cryphonectria parasitica.
- researches found that infecting this species with a double stranded RNA virus reduces its virulence
What is anastomosis and how does it play a role in hypovirulence in Cryphonectria parasitica?
- anastomosis allows spread of disease by different strains: hyphae of different strains fuse
- anastomosis isn’t possible for all strains, only those within the same VCG, so all VCGs must be infected
Differentiate between the relationship between bark beetles & fungi, and the relationship between ambrosia beetles and fungi. Which order of fungi are most commonly associated with both of these beetles.
- both in ophistiomatales
- bark beetles spread diseases
- ambrosia beetles aid in fungus farming
Name the pathogen(s) associated with Dutch Elm Disease. Illustrate/describe in detail the disease cycle, be sure to label all appropriate asexual and sexual fungal structures.
Ophiostoma lumi and novo-ulmi
- beetles lay eggs under bark of dead trees
- beetle galleries created
- produce synnema that produce spores that are spread by beetles to healthy trees
- fungus develops in tree xylem
- produce both ascospores and conidia
- can spread btwn roots
families within the order Hypocreales
Nectriaceae
Hypocreaceae
List and describe three major plant diseases caused by Fusarium, and identify the species responsible for these diseases, and any toxins they may produce.
Head scab of wheat and barley
- F. graminearum
- Deoxynivalenol aka vomitoxin
Ear rot of corn
- F. verticillioides
- fumonisin mycotoxins
Vascular wilts
- F. oxysporum
- activates plant defense in xylem
- cause of Panama disease of bananas
Describe/illustrate how/where sexual structures are formed in Claviceps purpurea. Label the structures appropriately.
- salem witch trials: convulsions, hallucinations, ants crawling on skin
- produce conidia that help it spread plant to plant
- hyphae develop into sclerotium- survival structure for winter
- develop stroma that produce perithecia (containing asci)
Describe/illustrate the disease cycle of the Zombie-Ant Fungus, Ophiocordyceps unilateralis.
- ants infected while foraging on forest floor: pick up asci
- germinate
- hyphae spread thru cuticle then musculature of the ant
- musculature cut off from brain- muscles are under control of the fungus
- climbs up to leaf or stem, paralyzed in place with a “death grip,” dies of starvation
- stroma and perithecia containing asci grow out of the ant and release ascospores that fall on the ground
Describe how you would determine if the mold growing in your bathroom is the “toxic mold” Stachybotrys? What toxin does it produce, and provide its taxonomic classification from class to family.
- wet environment
- growing on wood
- put tape on the mold and fold it in half- look at under microscope
- spores- black, rough edge, conidiophores have spores growing directly off the hyphae
How might you tell members of the Xylariales apart from other Sordariomycetes?
- black/brown ascospores with germ spore or slit
- black stromata
- asci w apical ring
- saprophytes
- parasites
- eg: dead man’s fingers
