Mycorrhizosphere- Unveiling the Hidden Life via Metagenomics

In a wide range of terrestrial ecosystems, different symbiotic mycorrhizal associations between plants and fungi occur, almost ubiquitously. Historically, these have chiefly been considered within the slightly narrow perspective of their effects on the uptake of dissolved mineral nutrients by distinct plants. Mycorrhizal fungi connect their plant hosts to the heterogeneously dispersed nutrients required for their growth, permitting the flow of energy-rich compounds required for nutrient mobilization whilst concurrently providing conduits for the translocation of mobilized products back to their hosts. In addition to growing the nutrient absorptive surface area of their host plant root systems, the extra radical mycelium of mycorrhizal fungi delivers a direct pathway for translocation of photosynthetically derived carbon to microsites in the soil and a huge surface area for interaction with other micro-organisms. With phylogenetic surveys of soil ecosystems it has been known that the number of prokaryotic species in a single soil sample exceeds the known cultured prokaryotes. The soil environment is a plentiful yet under-characterized source of genetic diversity that has countless potential to enrich our understanding of soil microbial ecology and provide bioactive compounds and enzymes useful to human society. The complete functioning and regulation of these mycorrhizosphere processes is still poorly understood but current progress and the metagenomic studies are reviewed.