Seminar: Dr Simona Radutoiu, Aarhus University

22 February

12.30 - 13.30

Nod factor recognition at root epidermis and its impact on microbiota assembly in Lotus japonicus

Protein-carbohydrate recognitions are central molecular events in host-microbe interactions. Legumes use LysM proteins to recognize carbohydrates produced by pathogens or symbionts. This suggests that an ancient recognition process has been used by legumes for evolution of elaborated mechanisms for perception of various carbohydrates.

In Lotus japonicus two LysM receptor kinases, NFR1 and NFR5, initiate root nodule formation and rhizobial infection after perception of Nod-factors secreted by M. loti. Lotus encodes for additional LysM receptors. We used reverse genetics coupled with gene expression and in planta functional studies, and have identified novel components involved in Nod factor signaling that contribute to the symbiotic interaction between Lotus and its nitrogen-fixing symbiont.

To understand how root nodule symbiosis influences the ability of Lotus to associate with other soil bacteria, we performed a comparative analyses of microbiota associated with soil-grown wild-type and symbiotic mutants. Community profiling of 16S rRNA gene amplicons identified a previously unsuspected role of the nodulation pathway in the establishment of distinctive bacterial assemblages in root and rhizosphere. These findings imply a role of the legume host in selecting a broad taxonomic range of root-associated bacteria that, in addition to nitrogen-fixing rhizobia, may have an impact on plant growth and ecological performance