Mycorrhizosphere interactions for legume improvement

Legumes, plant species of great agronomical and ecological interest, are known to establish beneficial symbiotic relationships with two types of soil-borne microorganisms: N2-fixing bacteria and arbuscular mycorrhizal fungi. Additionally, the legume rhizosphere harbors other associative beneficial microorganisms such as plant growth promoting rhizobacteria (PGPR). These microorganisms interact among themselves, and with legume roots, to develop the multifunctional legume mycorrhizosphere, a scenario of diverse activities relevant for legume productivity either in sustainable agriculture or in the maintenance of natural plant communities. This Chapter highlights strategic and applied research conducted so far, which have allowed a comprehensive understanding of the formation and functioning of the legume mycorrhizosphere. Manipulation of the microbial activities allows tailoring efficient mycorrhizosphere systems for improving legume productivity. The technology for the production of efficient rhizobial, free-living PGPR, and AM-fungal inoculants, nowadays commercially available, is likely to support sustainable and environmentally friendly low-input agrotechnological practices. The possibilities to use these bioproducts to help a sustainable development of legumes in either agrosystems or natural ecosystems are discussed.This study is included in the framework of the following Research Projects from the Spanish National Research Programme (R & D)-European Union (Feder): AGL 2006-09453-CO2-02/FOR, (2006–2009) and CGL-2006-02584/BOS (2006–2009).Peer reviewe