Rhizobial communities do not explain differential invasiveness of Australian acacias

The ability to fix atmospheric nitrogen plays an important role in the successful establishment of introduced plants. Questioning the widely held belief that generalism in mutualistic interactions between legumes and nitrogen-fixing bacteria (rhizobia) will benefit introduced plants, Keet et al. compared community richness and structures of rhizobial mutualists associated with widespread and localised Acacia species (Fabaceae) in South Africa.

Investigating among the roots of Acacias.
Investigating among the roots of Acacias.

Next generation sequencing data for the nodulation gene nodC enabled a comparison of the identity, species richness, diversity and compositional similarity of rhizobia associated with these acacias. A stable isotope analysis determined levels of nitrogen obtained from the atmosphere via symbiotic nitrogen fixation. No differences in mutualist richness and community structure were found between these two groups, indicating similar levels of rhizobial symbiotic generalism. These data support the hypothesis that introduced acacias harbour similar rhizobial communities; consequently their invasiveness may not be constrained by rhizobial mutualisms.

Reference

Keet, J.-H., Ellis, A. G., Hui, C., & Le Roux, J. J. (2017). Legume–rhizobium symbiotic promiscuity and effectiveness do not affect plant invasiveness. Annals of Botany, 119(8), 1319–1331. https://doi.org/10.1093/aob/mcx028