ABSTRACT
The beneficial effects that result from interactions between plants and microorganisms whether in a casual, mutualistic, or symbiotic association are of considerable ecological and agricultural importance. These interactions are receiving increased attention because of the potential gains in plant productivity and agriculture that can depend on these associations. Vascular plants, which originated in the late Silurian, may have been facilitated in their development by mycorrhizal associates which increased their nitrogen and phosphorus uptake efficiency. As a result new habitats were exploited and the development of complex tissues resulted. Lichens successfully occupy several unique ecological niches as a result of the symbiotic relationship between a fungus and a unicellular alga. The algal cells produce photosynthates for the fungus, and the fungus absorbs moisture and minerals and serves to protect that alga from high light intensity and desiccation. Bacteria adhering to moss in nature may affect protonemal growth and gametophore initiation.
