exam 3 (25,26,27) Flashcards
mycorrhiza
symbiotic assoc essential for one OR both partners - fungus and root of living plant
may be present with plants that do not for true roots
arbuscular mycorrhiza
dominant in roots tree like vesicles, tubular structure, stain roots
ecotmycorrhizal
no penetration in cell
fungal hyphae wrap around root cell
other mycorrhizas
mixtureee of arbuscular and ecto
ecoectendo, arbutoid, ericoid
both penetratin and less developed mantle (outside)
occurences of mycorrhiza
90% of all land plant belong to families that are commonly mycorrhizal
2% of plants form ECM associations BUT 60% of trees globally have ECM fungi on roots
non-mycorrhizal plant species
families with ruderals (brassicaceae, first colonizers) or diff root struct (Proteaceae)
plant succession mycorrhizas
None > AM > ECM > ERM (mix)
changes in nutrient type and availability: mineral to organic
AM and ECM trends
AM - more abundant in terms of plant species, common in P limited areas
ECM - more abundant in terms of land area, common in N limited areas
Benefits of mycorrhiza symbiosis
For fungi: C from plant For plants: 1. nutrients and water 2. protection from root pathogens 3. enhanced tolerance of heavy metals
mycoheterotrophs
plants don’t make out photosynthates, get CNP from fungi
nutrient content in mycorrhizal plants
higher than non-mycorrhizal
due to
1. extension of root system through fungal mycelium allows for larger area of soil to be exploited
2. hyphal diameter smaller than roots so access to smaller soil pores (inc soil volume exploited)
3. fungi have enzymes that allow them to capture nutrients from soil organic matter not normally accesible by plants
mycorrhiza plant diversity and productivity
inc diversity, inc biomass, inc hyphae, P used and put in plants more
mycorrhiza succession
common mycorrhizal network –> share ECM, same benefits, share hyphal connections
larger trees need the willow occurence first because of established ECM
mycorrhizal cost to plants
net cost = extra C gained from interaction - C expended
typically overall C gain is higher with M+ plants
15% of total plant C expended
environments for colonization ranked (light, P)
best low light, low P high light, low P high light, high P low light, high P
Past interaction between early-diverging mucuromycotan fungi and basal land plants (liverworts)
high thallus colonization (no roots)
fungal struct formed include arbuscules
Marchantia-colonizing fungi are AM, but called AML due to plant struct (AM-like)
photosynthesis with liverworts + early-diverging fungi
higher photosyn with AML colonization regardless of CO2 level
AML fungi and liver wort growth and reproduction
both in past and now
higher dry mass with AML
better growth by AML fungi regardless of nutrient level
more reproduction
fungi as disease agent
more common in plants
not common in animal
fungi disease in humans
300 species
worst associated with weakened immune systems
Fungi agricultural pathogens
crops - puccina (rust) and magnaporthe
spoilage - cladosporium and aspergillus
oomycetes:
phytophthora (potato blight), pythium, plasmopara
wheat rust
puccinia graminis
resistant varieties in 1960s. Ug99 is new rust that 90% of wheat is susceptible to
borlaug
pathogen spread
long distance spores dispersal (wind, atmosphere)
human transport
natural movement
attine ants
in american tropics, they cultivate basidiomycota as anti-bacterial covering that limits pathogen
leaves feed the fungus and the fungus prod nutrients that ants eat
