Plant growth promoting microorganisms, including PGP-rhizobacteria (PGPR),
phosphate solubilizing microorganisms (PSMs) and other symbiotic microorganisms like arbuscular mycorrhizas (AM)
fungi, may play a major role in developing a sustainable use of P resources. However, the success of the use of these
beneficial microorganisms requires an excellent understanding of the complex interactions taking place between the
different components of the complex plant-soil-microorganisms ecosystems.