Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses

Biological nitrogen fixation by Rhizobium -legume symbioses represents an environmentally friendly and inexpensive alternative to the use of chemical fertilizers in legume crops. Rhizobial inoculants, applied frequently as biofertilizers, play important role sustainable agriculture. However, inoculants often fail compete for nodule occupancy against native rhizobia with inferior nitrogen-fixing abilities, resulting low yields. Strains excellent performance under controlled conditions are typically selected but rates compared strains rarely investigated. Lack persistence field after agricultural cycles, usually due transfer symbiotic genes from inoculant strain naturalized populations, also limits suitability commercial inoculants. When rhizobial based on a high ability, they have superior their genetic adaptations local environment. Therefore, knowledge laboratory studies assessing competition understanding how diverse behave, together assays done conditions, may allow us exploit effectiveness populations elite breed specific host cultivar-rhizobial combinations. Here, we review current at molecular level nodulation advances tools competitiveness. We then describe ongoing approaches development emphasize future perspectives applications using multidisciplinary approach ensure optimal both partners.