Plant-Microbe Associations Flashcards
what are the positives of plant-microbe associations?
Essential for C and N recycling
Important for plant growth
strengthen the plant
what are the negatives of plant-microbe associations
detrimental to plant health
threat to crop production for human food and energy
threat to natural ecosystems
what does plant mutualism enhance
reproduction and nutrient uptake
where do ectomycorrhizal fungi proliferate
outside the root and between cells
where do endomycorrhizal fungi proliferate
within the cells of the root
describe the relationship between mycorrhizal fungi and a tree
what kind of relationship is it
the fungus gets carbon/sugars produced by photosynthesis
the tree receives nutrients from the soil
mutualistic
why is nitrogen fixation necessary?
what is the process?
atmospheric nitrogen is inert and therefore unavailable
nitrogenase fixes nitrogen into ammonium, uses ATP
describe the two-way signalling that occurs between rhizobia and plants
the plant root produces a flavonoid chemical that attracts rhizobia
the bacterium produces a Nod factor, identifying it as a symbiont
the plant prepares to form a symbiont nodule structure
what are rhizobia
nitrogen-fixing bacteria that attach to plant roots
what causes plant rot
saprophytes (fungi and bacteria)
digest then absorb using extracellular secreted enzymes
ensures C and N remain in circulation
what are the structural components of plant biomass
hemicellulose
cellulose
lignin
what makes an interaction into a disease
the pathogen must be able to overcome defences
the environment must tip the balance in favour of the pathogen
the host must be susceptible to the pathogen
facultative vs obligate pathogens
facultative - can attack living plant cells but also grow by themselves
obligate - can only grow using their specific host
biotrophic vs necrotrophic vs hemibiotrophic pathogens
biotrophic - feed on living plant tissue, don’t cause death
necrotrophic - kill plants cells and then feed
hemibiotrophic - initially biotrophic and then become necrotrophic
what are the biotrophic structures of fungi and oomycetes?
arbuscule
hyphae
haustorium
