ABSTRACT
The symbiosis between rhizobia and legumes is a special example of an association between prokaryotic and eukaryotic organisms (Perret et al., 2 0 0 0 ) that plays an important role in agriculture and has thus been intensively studied over the recent years. The rhizobia-legume symbiosis is the most important biological mechanism for providing nitrogen to the soil/plant system, reducing the need of plant crops for chemical fertilizers. This justifies the ecological importance of legume crops not only in the improvement of nitrogen nutrition to other crops, such as pasture or cereals, but also in land remediation.
