BIOL1002 Lecture Notes - Lecture 2: Casparian Strip, Ectomycorrhiza, Membrane Transport
6 Nov 2018
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Document Summary
Mycorrhiza: a symbiotic relationship between fungus and plants. Fungus supplies the plant with mineral ions that occur at low soil concentrations and in drought, water. 90% of all plant species form mycorrhizal associations, mycorrhiza are critical for evolution onto land. Fungal hyphae function as (cid:862)super root hairs(cid:863) (cid:271)y in(cid:272)reasing the a(cid:271)sorption surfa(cid:272)e area. Ectomycorrhiza hyphae access nitrogen (n) compounds that (cid:449)ouldn"t other(cid:449)ise (cid:271)e a(cid:448)aila(cid:271)le to plant. Hyphae produ(cid:272)e digesti(cid:448)e enzymes (peptidases) which release n-containing amino acids in decaying organic matter. N absorbed by hyphae is transported to the plant root. Fungi play an important role in plant phosphate acquisition. Arbuscular mycorrhiza produce an extensive hyphal network outside root 40 m/g soil, transports nutrients from up to 15 cm away. Roots are highly successful miners of scarce mineral resources concentrating mineral ions from a dilute soil environment. Therefore, mineral ions are accumulated against their concentration gradients. For example, while soil phosphate concentration is <1mm, cytoplasmic phosphorous concentration is ~1-10mm.
