The apoplast of ectomycorrhizal roots – site of nutrient uptake and nutrient exchange between the symbiotic partners

  • H. BÜcking
  • R. Hans
  • W. Heyser


Between 80 and 90% of all known plant species live in close interaction with mycorrhizal fungi in a mutalistic interaction, the mycorrhizal symbiosis. Mycorrhizal root tips with their extramatrical mycelium increase the absorbing surface area of mycorrhizal roots and contribute significantly to the nutrient uptake of plants. The following paper deals with the role of the apoplast for nutrient uptake and nutrient exchange between both partners. Investigations by use of fluorescent dyes as apoplastic tracers showed that the fungal sheath of the ectomycorrhizal roots does not act as an effective apoplastic barrier for the entry of nutrients into the mycorrhizal root cortex. However, nutrients such as P can be absorbed by hyphae of the extramatrical mycelium or the fungal sheath and the transfer to the host plant is controlled by the fungal symplast. The results indicate that the uptake of P by the extramatrical mycelium and the transfer across the interfacial apoplast to the mycorrhizal host plant is not primarily regulated by the host plant demand for P, but by the flux of carbohydrates from the mycorrhizal host plant to the fungal symbiont. A model system shows how the carbohydrate and P exchange between both symbiotic partners is possibly linked.

Key words

apoplast ectomycorrhiza interface nutrient exchange P transport 


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Copyright information

© Springer 2007

Authors and Affiliations

  • H. BÜcking
    • 1
  • R. Hans
    • 2
  • W. Heyser
    • 2
  1. 1.Biology DepartmentState University of New JerseyUSA
  2. 2.University Bremen, Center for Environmental Research and TechnologyGermany

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