Mycorrhizae Flashcards
What is Mycorrhizae?
Mycorrhiza
•Mycorrhiza is Greek for “fungus root”
•Plural - Mycorrhizae
•Symbiotic (mutualistic) relationship between plant and fungus. Fungi and plants can survive alone so it is termed a Facultative mutualistic relationship
•Plants provide sugars to fungus
•Fungus provides nutrients e.g. phosphorous to plant and can extend effective absorption area of root
• Fungus associated with roots
• > 75% of all plant species have mycorrhizae
• symbiotic – facultative mutualism
– both partners benefit, but can live apart
• great for Phosphorus (P) mobilisation and absorption, P is immobile in soil.
• fungus forms mantle of threads (hyphae) around or into root
• propagation – may need to include some ‘fungus soil’
What is Rhizobia Symbiosis?
Rhizobia symbiosis
Symbiotic (mutualistic) relationship between legumes and rhizobia bacteria
Joint effort between plant and bacteria - together they construct root nodules which involves changes to the root hairs
Bacteria fixes nitrogen as ammonia and nitrates for plant Plant gives bacteria sugars
Red compound in root nodule is an oxygen binding pigment – Leghaemoglobin. Creates low oxygen environment for nitrogen fixing enzyme in bacteria to work yet provides enough oxygen for bacteria to live
• Atmosphere 80% Nitrogen, but not available to plants
• Some bacteria can convert N to nitrates
• These can be absorbed by roots
• legumes (Fabaceae e.g. peas, beans, alfalfa, Acacias) have root nodules
• nodules contain bacteria (Rhizobia)
• again facultative mutualism
• Fabaceae the third largest family of flowering plants
What are Proteoid Roots?
Proteoid roots
• Theymayformatwo-tofive-centimetre-thickmat just beneath the leaf litter. They enhance nutrient uptake, possibly by chemically modifying the soil environment to improve nutrient solubilisation.
• Asaresult,plantswithproteoidrootscangrowin soil that is very low in nutrients, such as the Phosphorous-deficient native soils of Australia
• First discovered in Proteaceae
