ABSTRACT
The rhizospheric ambient is coupled to several echophysiologic systems. The antibiosis is part of this context, serving as a selective mechanism owned by the more adapted species. Biologically active substances, exuded by roots of some plant species, can be extracted with organic solvents, generating products with pharmacological regard. Roots, obtained by genetic transformation of plants with Agrobacterium rhizogenes, potentially open the way to the obtention of such bioactive compounds, without having the variations imposed by the ambient. Microorganisms, symbionts or not, like bacteria, actinomicets and fungi can also produce potentially bioacteive substances. In the vegetable, the existence of such metabolites seems to be related to its chemical defense against the pathogens attack. In like fashion, microorganisms produce similar substances in order to help a better surviving, when the ambient conditions are hostile or accentingly competitive.
Key words:
antibiosis; rhizosfere; secondary metabolites