A Little Help From Your Friends Flashcards
What kind of symbiotic relationships do exist?
Mutualistic
Parasitic
What do plants bring to the table in mutualistic relationships?
Food in form of carbohydrates
Shelter
What do plants generally gain in mutualistic symbiotic relationships?
Greater access to nutrients in the soil
Protection from parasites and predators
How did vascular plants evolve
From algae which formed a symbiotic relationship with aquatic fungi
Algae provided carbohydrates
Fungi provided inorganic nutriebts
How is the mutualistic relationship with fungi and plant roots called?
Mycorrhiza
What does the fungi provide the plant with mostly in mycorrhiza?
Phosphate
WHat are the two main mycorrhizal associations?
Ectomycorrhizae
Endomycorrhizae
How does a ectomycorrhizae work?
Also known as sheating mycorrhizae
The fungus surrounds the root, altough fungal hyphae also penetrate the root and grow between its outer cells (cortex)
How does a endomycorrhizae work?
Grow WITHIN the root and penetrate its cells - thsi forms an arbuscule
What is an arbuscule
A structure that a fungi forms in plants roots that resembles a cauliflower head - it provides a large surface area for uptake of sugars
It never ruptures the plants plasma membrane of the plant cells
Can mutualistic fungi just enter the plant?
They are recognized as alien organism by the plant
The plant recognizes two elicitor molecules during this encounter - those derived from the fungi itself and those created by the damage inside the plant
Ectomycorrhizal fungi lack enzymes that damge the plants cell walls - so they dont produce damage induced elicitors that trigger an immune response
The plant only triggers its defences as the fungus starts its interaction with the host - these defences then get suppressed by the fungus
What are effectors?
Molecules which block perception of elicitors
What is MiSSP7?
The most highly up regulated gene in the symbiosis of the fungus with plant roots
It encodes an effector protein which is indispensable for the establishment of a mutualistic symbiotic relationship between the fungus and the roots
How does MiSSP7 work?
1.The protein is secreted by the ectomycorrhizal fungus, once it detects signals of the plants roots
2.The protein is imported into plant cells via endocytosis (Molecules ate transported into the cell by engulfing them)
- Once in the cell it is transported into the nucleus where it alters the expression of genes involved in establishing the symbiosis
What makes it hard to work with arbuscular mycorrhizal fungi?
The fungi is biotrophic and cant grow away from its host
What is SP7?
An effector protein produced by arbuscular mycorrhizal fungi
It interacts with a transcription factor that is induced by the plant when it gets attacked -> thsi way no defences get activated
It is an universal effector
Which plant hormoned interact with the fungi in soil, stimulating its growth?
Strigolactones
How does the fungi signal a plant it is ionterested in symbiosis?
With molecules called „Myc factors“ which trigger a reprogramming of gene expression in plants
How can a plantregulate the symbiosis formed with organisms?
It is called autoregulation - when one half of the root already formed a symbiosis with a fungi, the other won‘t
It is suggested, that an inhibitor that gets produced upon mycorrhizal establishment is responsible for this