The vesicular - arbuscular (VA) mycorrhizal fungi are geographically ubiquitous soil
inhabitants and form universal symbiotic relationship with plants from every phylum.
These fungi link host plants with host soils and their biota in the mycorrhizosphere and
play  an  important  role  in  plant  health,  productivity  and  soil  structure. Although  VA
mycorrhizal  fungi  do  not  show  any  host  specificity,  there  is  increasing  evidence  that
various  climatic  and  edaphic  environmental  factors  such  as  land  use  and management
practices,  physical,  chemical  and  biological  properties  of  host  soils  and  host  plant
characteristics  influence  their  occurrence,  taxonomic  distribution  and  effectiveness.
The interaction of these factors with vesicular-arbuscular mycorrhizae (VAM) is poorly
understood except in a few cases. It is now very clear that VA mycorrhizal associations are
ecologically significant factors that require more attention than previously accorded.
This  paper  discusses  the  occurrence,  distribution  and  significance  of  VAM  in
environmentally  stressed  soil  conditions  that  limit  plant  growth  such  as  drought,
waterlogging and salinity.