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35 Cards in this Set

  • Front
  • Back
Classify, draw and label Alternaria.
P-Deuteromycota (Fungi Imperfecti)
C- (Form Class) Hyphomycetes
G-Alternaria (Macrosporium)

Did you get:
-host (tomato) leaf
-point of attachment to condidiophore
-multicellular conidium (spore)
Classify, draw and label Fusarium
P-Deuteromycota (Fungi Imperfecti)
C- (Form Class) Hyphomycetes

Did you get:
Classify, draw and label Lobaria
P-Ascomycota (Lichenized ascomycota)

Did you get:
-upper cortex
-lower cortex
-algal layer
Classify, draw and label Physcia
P-Ascomycota (Lichenized ascomycota)

Did you get:
-algal layer
-thalline margin
-2 celled ascospore
What are some defining characteristics to the Phylum Deuteromycota?
-AKA Fungi Imperfecti
-classification is based on asexual sporulation and cell form
-most have septate hyphae and multinucleate cells, most septa have a single pore
-have sexual characteristics similar to Ascomycetes
-if an asecual species has characters clearly relating it to the Zygomycota or Basidiomycota, then it is not considered to be a Deuteromycote
-economically and medically important
-genetic variaty by means of PARASEXUALITY
-method used by Deuteromycota to get some genetic variation (because it is predominantly asexual)
Three stages in the parasexual cycle:
1) Heterokaryosis
-by hyphal fusion or mutation
-heterokaryotic hyphae contain nuclei with different genotypes

2) Diploidization
-pretty much like karyogamy

-like a shitty mitosis (ie: while dividing to increase numbers, it doesn't disperse the chromosomes evenly, and thus, they act as new 'gametes' therefor get variation)
-creates ANEUPLOID nuclei (2N +/- 1)
-aneuploids are pretty unstable and randomly loses the unparied chromosomes, returning at least one nucleus to the haploid state
What 3 Form Classes can Deuteromycota be divided into?
What are some defining characteristics to the Form Class Blastomycetes?
-yeast like fungi, but may produce a limited mycelium
-includes the yeast Candida albicans, a member of the community of micro organisms that lives on our skin
What are some defining characteristics to the Form Class Hyphomycetes?
-conidia are produced in a variety of ways, of which we chall consider only 2; THALLIC & BLASTIC

Thallic Development
-creates conidia from pre exisiting strutures like hyphae
-these are often called ARTHROSPORES or OIDIA
-thallic conidiation is analogous to sporogenesis in Oomycetes and Zygomycetes where the hypha breaks up into spores (pg.141)

Blastic Development
-forms new cells during conidiogenesis on flask shaped structures called PHIALIDES (pg.142)
Draw a x-sec of a leaf, showing the location of the spores.
Did you get:
-multicellular spores in chains
-wilted edges of the leaf
Draw Fusarium spores.
-sickle shaped
-3 or more transverse septa
-attached end is relatively blunt
-bigger than micro... no shit

-sphericial to ovoid
-usually aseptate
-may occur in chains

**F. oxysporum has both micro and macro; F. solani has lots of macro**
What are the 2 factors needed to spread Dutch Elm Disease?
1)Ophiostoma ulmi
-the fungus/disease causing agent

2)Scolytus multistriatus
-beetle/disease vector
What does Scolytus multistriatus do?
-the beetle vector of Dutch Elm
-feesd on phloem
-beetles lay thei eggs in straight channels carved in the wood beneath the phloem layer
-the egg laying channel is PARALLEL to the grain of the wood
-eggs hatch and the larvae feed by cutting RADIATING GALLERIES under the bark. Galleries get wider as the larvae gor, beetles emerge through holes in the bark at the end of each feeding gallery
-feeding galleries cut across the phloem cells, releasing sugary sap to nourish the larvae (and fungus), and so depriving the tree
-this severely weakens the tree, making it susceptible to infestation
What does Ophiostoma ulmi do?
-the fungus causing Dutch Elm disease
-completely dependant on the beetle vector to get it around
-combo of agressive vector and virulent fungus that led to the destruction of millions of American elms
-Ophiostoma is an ascomycete
-cycle includes sexual and asexual stages, each of which produces infective spores (conidia)
-sexual stae is relatively unimportant during colonization of new areas
-it is DIMORPHIC = asexual stage has both hyphal and yeast forms
hyphae and yeast cells grow in the beetle galleries and pupal chambers, with the hyphae producing asexual spores (form genus for this stage is Graphium)
-yeast cells and spores provide most of the inoculum that is spread by the beetles, cbcause they stick to the beetles bodies
-in spring and early summer, when tree sap is abundant, hyphae invade the water conducting xylem vessels of the wood
-there, they produce a slightly different kind of asexual spore called Sporothrix
-Sporothrix spores disperse and then germinate to produce more hyphae and repeat the cycle, and they can grow as single cells
-both forms are carried throughout the xylem vessles and do not require a living tree to survive
How does Ophiostoma kill the tree?
-spores, hyphae, and yeast cells can clog xylem vessels, preventing water transport to and through the leaves, which then die
-yeast cells can live and reproduce in fluid, but spores generally need aerobic conidtions, even if they later are surrounded by a gluey drop
-to generate and maintain a dry surface, hyphae serete proteins called HYDROPHOBINS (cerato-ulmin is Ophiostoma's way), which aggregate to form a WATER REPELLANT FILM
-when hydrophobins are produced in xylem, those cells can no loner transfer water from the roots to the leaves, which then die
-without leaves, the tree cannot produce sugars by photosynthesis
What 3 things can we do to protect Saskatoon from Dutch Elm Disease?
1) Do not bring elm logs into the city for firewood

2) Do not prune trees after the dates recommended by the city

3) Be aware if one of your elm trees suddenly has wilting leaves on one of its branches
What are Lichens?
-often used as textbook examples of symbiosis
-MYCOBIONT (fungus usually of Phylum Ascomycota) and PHYCOBIONT (algae usually cyanobacteria or blue/green)
-mycobiont receives its organic nutrients from the alga while the algal cell is physically protected from environmental stress by the mycobiont
-association of the mycobiont and phycobiont is an obligate relationship since the mycobiont does not occur free living in nature
What are the 3 growth forms of Lichens?
1)Crustose Lichens
-form a crust over the substratum on which they grow and are particularly common on prairie boulders around Saskatoon
-lack a lower cortex and is impossible to detach the thallus from its substrate without destroying it

2)Foliose Lichens
-have a leafy structure and are commonly encountered on tree turnks and the ground in moist woods
-a lower cortex almost invariably deimits the base of the thallus
-cells of the lower cortex often produce hyphae which aggregate to form attaching structures called RHIZOIDS

3)Fruticose Lichens
-have a cylindrical structure and grow upright on the ground or hang from the branches of trees
-do not have upper and lower surfaces so that the medulla either fills the axis of the plant or sometimes surounds a hollow center or possess a central, fibrous strand
Where are Lichens found?
-able to survive on apparently inhospitable environments as prairie boulders, which appear to be the driest of habitats
-however, because rocks lose more heat than the surrounding air during the night, water condenses on their surface and is absorbed by the lichens
-the moist lichens are then able to photosynthesize for a short time each morning until their temperature rises due to solar heating and the thallus dries out, stopping all metabolic activity
Why do Lichens grow so slow?
-majority of water is from rocks, therefor no surplus
-this allows them to photosynthesize only for a short time each morning until their temperature rises due to solar heating, and the thallus dries out, stopping all metabolic activity
-the other gorwth limiting factor is that the algae are photosynthesizing for both partners so there is very little excess photosynthate available for growth

Lichens are very hardy and therefor can live anywhere.

-although they live on shitty places, they are very sensitive to pollution
What are the top 3 Alga (Phycobionts) in lichens?
1)G-Trebouxia (Chlorococcales, Chlorophyceae)

2)G-Nostoc (Cyanophyta, Nostocales)

3)G-Trentepohlia (Ulotrichales, Ulvophyceae)
What are the 3 classes that you will find Lichenized Ascomycetes in?
-almost all the crustaceous app with small perithecia

-characterized by disk like apothecia

-not important
What are Gelatinous Lichens?
-a thallus structure in lichenized Discomycetes
-when moist, blue green algae are randomly dispersed throughout the thallus amongst the fungal hyphae and do not form a distinct layer (HOMOIMEROUS STRUCTURE)
-most look similar to Nostoc except that they exhibit marked marginal growth so the thalli become lobed
-they are foliose and can be recognized by their dull, dark green color
-gelatinous texture when moist is due to the absorption of water by the mucilaginous sheathes of the Nostoc colonies
-a thallus structure in lichenized Discomycetes
-more common then the HOMOIMEROUS STRUCTURES found in Gelatinous structures
-algae are limitd to a thin layer, sandwiched between 2 layers of fungal tissue
-upper surface of the thallus is a layer of cortical fungal tissue
-cortex has a cellular structure caused by cross wall formation in the hyphal tips, which swell as their walls subssequently thicken (gives color to the lichens)
-color from MELANIN(brown), PARIETIN (orange), USNIC ACID (yellow)
-colors serve to shade and protect the algal layer below the cortex from the harmful effect of intense solar radiation to which many lichens are exposed
-MEDULLA makes up the greates volume and mass of the lichen thaand consists of a loose weft of fungal hyphae
-usually colorless
-excrete oxalate crystals and LICHEN SUBSTANCES which are helpful in ID'ing lichens
-MYCOBIONT HYPHAE penetrate the cell walls of PHYCOBIONTS, facilitating the transfer of carbohydrates to the fungus, but don't penetrate the cell membrane
-PHYCOBIONT is limited to the upper part of the medulla where it is in the best position to capture incident radiation
**pg. 151**

-a puncture found on the lower cortex of some large foliose lichens, aerating structures

-pseudocyphellae are similar structures except that the exposed medulla is virtually unmodified

-a grunule like structure found on the surface or withing the thallus of some lichens possessing green algae
-granules contain blue gren algae which fix atmospheric nitrogen
-the organic nitrogen is then transported to the medullary tissue of the mycobiont

**pg. 152**
-algal rim of surrounding the hymenium layer of the apothecium
-represents the most extreme form of lichenization of the fungal partner
Describe the ascus of Lichenized Discomycetes.
-asucs wall is much thicker so that it appears similar to some BITUNICATE ASCI of the unlichenized Ascomycetes
-this difference in ascus structure is sufficient to warrant a separate order, the Lecanorales, being established for lichens with discoid apothecia
-spores are not disseminated with algal cells and in order for a new lichen to form in nature, the ascospore must germinate in the vicinity of a suitable algal cell or colony
-this obviously creates a problem since most phcobiont can't occur free living
How do Lichens Reproduce?
-FRAGMENTATION of the thallus by mechanical injury is an important means of vegetative reproduction in many FRUTICOSE SPP
-many lichens have also evolved special propagules to facilitate this process, SORIDEA and ISIDIA (another flashcard)
-not much for sexual reproduction, but without it, how can you get variation?
-most lichens produce soredia, isidia, ascospores or conidia
-the latter are funal spores produced in flask shaped structures not unlike perithecia
-any of these propaules can land on existing lichen thalli and thus new mycobiont genotypes become incorporated with the existing one by associating with the algal partner
-in this way, even somatic mutations can come to have a wider distribution in the population
-meiotic recombinations are, of course, also possible in those lichens which produce ascospores
What is SOREDIA?
-a propagule on lichens that facilitate fragmentation on FRUTICOSE SPP
-flour like, microscopic progagules of a few algal cells surrounded by a loose weft of fungal hyphae, therefor containing both mycobiont and phycobiont
-they erupt through the cortex in large clusters called SORALIA
-individually soredia are light enough to be blown away in the wind

**pg. 154**
What is ISIDIA?
-a propagule on lichens that facilitate fragmentation on FRUTICOSE SPP
-larger than soredia
-have a similar structure to the thallus (ie: with a cortex and medulla)
-too heavy to be transported by wind, but are readily detached by animals
-these begetative propagules grow into new thalli upon landing in a suitable habitat

**pg. 156**
Give 5 examples of Crustose Lichens.
1)Rhizocarpon geographicum
-AKA map lichen
-yellowith green tissue is the lichenized thallus
-surrounded by black, unlichenized tissue, the HYPOTHALLUS
-angular black structures embedded in the thallus are ascocarps - apotheciae

-aquatic habitat
-thallus broken up into angular units called AREOLAE, but lacks a hypothallus
-ascocarp are perithecia embedded in the thallus (rather than apothecia)

3)Dimelaena oreina
-lobate thallus margin and dark apothecial disk, exposed hymenium, protected by a surrounding thalline tissue/margin
-yellow pigment is usnic acit

4)Graphis scripta
-corticolous (grows on cortex of tree)
-apothecia (called Lirellae) resembles Arabic writing
-thallus is continous (ie:not broken up into areolae) and found beneath outer cells of the bark

-poorly developed thallus
-cortex not differentiated
-appears flour like yellow
-apothecia (black pins) are stalked and called MAZAEDIA
-hymenium disintegrates to release the ascospores
Give 7 examples of Foliose Lichens.
-gelatinous lichen but possesses an upper and lower cortex (1 cell layer thick)
-dull grey/green colour due to the blue/green phycobiont

2)Parmelia sulcata
-SOREDIATE, soredia developing along cracks (soralia) in the upper cortex
-soralia are elongate and branched

3)Lobaria pulmonaria
-large foliose spp and is most typical of maritime climates
-red apothecia and marginal peglike ISIDIA
isidia are concentrated along the ridges and margins of the thallus lobes
-young isidia look similar to soredia, but the cortex is not broken open
-underside is partly covered by rhizoids

4)Peltigera apthosa
-large folios spp of the forest floor (TERRICOLOUS)
-phycobiont is green but the brown structures on the thallus surface contain blue/green alga
-cephalodia (on the upper cortex, look like warts) are able to fix atmospheric nitrogen for use by the rest of the thallus

5)Lobaria pulmonaria
-has a green ala as its phycobiont and also has INTERNAL CEPHALODIA

-foliose lichen with APOTHECIA
-thalline maring has the same structure as the thallus and it protects the hymenium on all sides except the upper surface
-asci have 8 ascospores
-have paraphyses
-has 1 septate (2celled spores) which have heavily pigmented brown walls

-UMBILICATE growth form
-specialized tpe of foliose lichen in which there is only one central attachment point, the UMBILICUS
Give 4 examples of FRUTICOSE LICHENS
1 & 2)Usnea (cylindrical) & Evernia(flat)
-pendulous (ie: hanging)

-old man's beard

4)Cladina spp
-AKA caribou moss
-terricolous/erect lichens
-erect branching stems are called PODETIA
-C. stellaris is yellow