Abstracts |
Different symbiotic mycorrhizal associations between plants and fungi occur,
almost ubiquitously, in a wide range of terrestrial ecosystems. Historically, these have mainly
been considered within the rather narrow perspective of their effects on the uptake of dissolved
mineral nutrients by individual plants. More recent research has placed emphasis on a wider,
multifunctional perspective, including the effects of mycorrhizal symbiosis on plant and
microbial communities, and on ecosystem processes. This includes mobilization of N and P from
organic polymers, release of nutrients from mineral particles or rock surfaces via weathering,
effects on carbon cycling, interactions with myco-heterotrophic plants, mediation of plant
responses to stress factors such as drought, soil acidification, toxic metals, and plant
pathogens, as well as a range of possible interactions with groups of other soil micro-organisms.
Mycorrhizal fungi connect their plant hosts to the heterogeneously distributed nutrients required
for their growth, enabling the flow of energy-rich compounds required for nutrient mobilization
whilst simultaneously providing conduits for the translocation of mobilized products back to
their hosts. In addition to increasing the nutrient absorptive surface area of their host plant
root systems, the extraradical mycelium of mycorrhizal fungi provides a direct pathway for
translocation of photosynthetically derived carbon to microsites in the soil and a large surface
area for interaction with other micro-organisms. The detailed functioning and regulation of these
mycorrhizosphere processes is still poorly understood but recent progress is reviewed and
potential benefits of improved understanding of mycorrhizosphere interactions are discussed. |