The alien A invasive does not infiltrate the native soil rhizobial symbiosis networks.

Using -rhizobia- interaction networks, we address first the soil invasion success of , and second, we report either -rhizobia partnership should form an isolated module within the symbiosis interaction network. Different indexes were used to determine model invasion success and the network topology. Our results indicated that invasion decreased soil microbial biomass, basal respiration, and enzymatic activities. Housekeeping gene-based phylogeny showed that the invasive is exclusively associated with a novel putative nodulating sp. not considered, up to now, as a natural symbiont of this species, and the native legume nodulating strains, belonged to three new putative undescribed distinct chromosomal lineages within the and genera. Analysis using gene identified one symbiovar for symbiont (sv. ) and three symbiovars for endosynbionts (sv. , sv and sv. . Moreover, -rhizobia interaction networks are significantly modular with high levels of specialization. Network topology remained consistent over the invasion gradient, whereas native legume-associated rhizobia underwent significant change as acacias took over more the landscape. The absence of mutual overlapping networks emphasizes the importance of the simultaneous invasion of rhizobia-acacia species complexes in successful acacia invasion, suggesting unique interactions that often arise and evolve.