Symbiosis Flashcards
Legumes signal to rhizobacteria through production and release of:
a) Flavanoids
b) Strigolactone
c) Myc factors
d) Nod factors
a) Flavanoids
Rhizobium bacterioids fix nitrogen in a:
a) Microanaerobic, nitrogen poor environment
b) Microaerobic, nitrogen rich environment
c) Anaerobic, nitrogen poor environment
d) Aerobic, nitrogen rich environment
b) Microaerobic, nitrogen rich environment
What bacterial species forms a symbiotic relationship with legumes?
Rhizobium
What bacterial species forms a symbiotic relationship with woody plants and trees?
Frankia
Gram +ve actinomycete
What bacterial species forms a symbiotic relationship with squid?
Vibrio
What do bacteria produce in response to flavanoids released by the plant to activate the symbiosis signalling pathway?
Nodulation factors
(Nod Factors)
What is the main route of O2 diffusion in a nitrogen-fixing nodule?
Through the apex, which generates a longitudinal O2 gradient
What is the concentration of the central nitrogen-fixing zone containing Rhizobium bacteroids?
Less than 50nM
How is oxygen diffusion facilitated in the central nitrogen-fixing zone?
High concentrations of Leghaemoglobin
What bacteria do Soybean plants form a symbiotic relationship with?
Bradyrhizobium japonicum
Plants signal to arbuscular mycorrhizal fungus through production and release of:
a) Flavanoids
b) Strigolactone
c) Myc factors
d) Nod factors
b) Strigolactone
What do fungi produce in response to strigolactane released by the plant to activate the symbiosis signalling pathway?
Mycorrhizal facors
(Myc factors)
What is involved in arbuscular mycorrhizal fungus infection of plant roots?
Infection peg from the hyphopdium allows fungal hyphal growth into the root epidermal cell
How does arbuscular mycorrhizal fungus colonise the plant root cortex?
Through intercellular hyphal growth
What does the mutualistic association between mycorrhizal fungi and plants provide the fungus?
Access to plant carbohydrates (glucose & sucrose)
