Primitive groups of fungi

Question 1

Zygomycota

Answer 1

• represent about 1% of all described fungi spp
• colonizers of substrates with C sources (sugars/starch)
• name derived by the way they reproduce sexually

Question 2

How do zygomycota reproduce sexually

Answer 2

• funsion of morphologically similar gametangia

- formation of zygosporangium (teleomorph)

Question 3

Characteristics of zygomycota

Answer 3

• heterothallic and homothallic forms
• zygosporagium normally thick walled
• coenocytic mycelium
• asexual reproduction by sporagiospores
• emphasis placed on asexual characters

Question 4

Mucorales

Answer 4

• 300+ spp including common saprobes and plant/animal pathogens
• 1/3 of all zygomycetes
• well developed mycelium
• Aseptate

Question 5

Zygomycota adaptions

Answer 5

• teleomorphs: function for long term survival

- anamorphs: function of dispersal

Question 6

Pilobolus

Answer 6

• zygomycete that uses a light spot to aim its sporagia toward a good food source, eventually ruptures to disperse
• black dot: sporangium
• main bubble: subsporangial vessicle

Question 7

Glomeromycota

Answer 7

• group of fungi that form symbiotic relationships with the roots of trees
• 200 spp
• grow between root cortical cells and produce large vesicles(food reserves)

Question 8

Mycorrhizas

Answer 8

• fungi in symbiotic relationships with roots
• helps plants take up phosphorous and nutrients
• about 70% of plants form AM mycorrhizae
• ubiquity of association is striking feature

Question 9

When did mycorrhizae and plant associations begin

Answer 9

• very early in plant evolution

- fossil evidence

Question 10

Chytridiomycota

Answer 10

• only members of kingdom with motile cells
• zoospores and gametes have single, posterior, whiplash flagellum
• chitinous cell walls

Question 11

Economic impacts of chytrid fungi

Answer 11

• vectors of damaging viruses
• parasitic on pollen grains
• sp Synchytrium endobioticum causes wart disease of potato

Question 12

Phyllum Neocallimastigomycota

Answer 12

• anaerobic fungi in digestive tract of larger herbivores
• no observed sexual reproduction
• zoospores can survive months in aerobic environments
• play role in fiber digestion

Question 13

Phylum Blastocladimycota

Answer 13

• alteration of generations - very unusual in fungi (gametophyte/sporophyte)
• anisogamy: one gamete is larger than the other, and one is motile