Mycorrhizae Rhizobia Flashcards
what is the core plant microbiota
the microbiota associated with a specific species or genotypes, independant of environmental conditions
what are core plant microbiota believed to be
microvial taxa
crucial if not required for growth and survival of species
2 groups of core microbiota
mycorrhizae
rhizobia
what is mycorrhizae
fungal species which associate with plant roots in a symbiotic relationship
when do mycorrhizae occur
when the hyphae of mycorrhizae enter the root organ
what is hyphae
main tissue of a fungal species
the body
what do the plant and fungi both get out of a mycorrhizal association
- fungus is receiving carbohydrates from the plant
- plant benefits from increased absorption area for water and minerals since mycorrhizae acts as extended root system
role of hyphae with roots
fungus absorbs water and minerals through cell surface
more surface area= greater interface with which to absorb water and minerals
what are the 2 classes of mycorrhizal associations
ectomycorrhizae
endomycorrhizae
what is ectomycorrizae
a mycorrhizal association which does not penetrate into cells of the host
what is ectomycorrhizae
association which forms a complex sheath of hyphae around the root tip (mantle)
what is believed to be the main fungal group responsible for tree to tree communication
ectomycorrhizae
what is endomycorrhizae
mycorrhizae association where hyphae penetrates the host cell
what is the most common type of endomycorrhizae
arbuscular mycorrhizae
what is arbuscular mycorrhizae
a form of endomycorrhizae where the hyphae of the fungus penetrates the cells of the cortex
what are strucutes of penetrated arbuscular mycorrhizae
arbuscules
vesicles
what are arbuscules
highly branching hyphae that enters the plasma membrane of the cell and increases surface area of the hyphae inside the cell
what are vesicles
large spherical growths of fungal hyphae within the plant cell
what are the other mycorrhizae
ericoid
orchid
arbutoid
what is ericoid mycorrhizae
special class of endomycorrhizae found only in the ericaceae family
what is the ericaeae family
mainly wtland plants: blueberries, cranberries, rhododendrons
what do ericoid mycorrhizae specialize in
nitrogen acquisition
what is the unique form of ericoid mycorrhizae
the hyphae form coils
what is orchid mycorrhizae
a mycorrhizal association unique to orchid species
how do seeds in orchidaceae with no endosperm get energy for growth
mycorrhizal symbiont
what is the growth pattern of the orchid mycorrhizae
hyphae penetrate the cortical cells and the plasma membranes of the cortical cells
what are pelotons
very dense fungal groupings
what do orchid mycorrhizae provide early in the association
carbon and minerals
what do orchid mycorrhizae provide when plant is mature and photosynthesizes
minerals
what are arbutoid mycorrhizae
very rare form of mycorrhizal association only found in 2 groups of the ericeae family
what are the rhizobia symbioses
group of bacterial species that associate mainly with members of the fabaceae family
what happens when rhizobia is associated with a plant host
it can express genes to fix atmospheric nitrogen into a form that the plant can absorb
what does plant provide to rhizobia in return
sugars
what is nodulation
process of symbioses with rhizobia
what are the steps of rhizobial symbioses
- rhizobia bacteria associate with an emerging root hair
- bacteria release signals to tell the plant that the bacterial cells are present
- in response, the root hairs elongate and begin to form coiled structures trapping the bacteria
- cell walls of the root hair then begin to collapse inward creating a passage from the soil surface to the cortex cells
- in the cortex, rhizobia cells travel to cortex cells and inscide the cell they begin to multiply enlarge and form a nodule
what is an infection thread
passage from the soil to the surface of the cortex cells
what is a nodule
a plant cortex cell filled with nitrogen fixing bacteroids that is connected to the vasculature of the root
what are bacteroids
mature rhizobia cells actively fixing nitrogen
what is the symbioses relationship in plant master
plant initiates the symbiosis
plant gives sugar to symbiont in exchange for minerals
