An international team of experts from Denmark, Italy, France, and Japan
identified a new receptor involved in symbiosis between legumes and
nitrogen-fixing rhizobia. The results are published in eLife journal.

To start symbiosis, the legumes use certain receptor proteins that can
recognize the Nod factor proteins produced by bacteria which are crucial in
establishing the host-nonhost link between legumes and rhizobia. The
presence of two well-known Nod factor receptors (NFR1 and NFR5) belonging to
a large family of so-called LysM receptor kinase proteins implies that other
similar receptors may be involved in Nod factor signaling as well. Thus, the
researchers identified the role of another LysM receptor kinase called NRFe
by studying a model legume species, Lotus japonicus.



Their findings showed that NFRe and NFR1 share similar and distinct
biochemical and molecular characteristics. NRFe is expressed primarily in
the cells located in a specific area on the surface of the roots. Compared
to NFR1, NFRe has a restricted signaling capacity restricted to the outer
root cell layer. When NRFe was mutated, less Nod factor signaling was
activated inside the root and fewer nodules were formed.

NFR1-type receptors have also been found to be present in other plants that
do not form a symbiotic relationship with rhizobial bacteria. This finding
could provide a basis for new biotechnological targets in non-symbiotic
crops, to enhance their growth in nutrient-limiting conditions.

[mbg.au.dk]
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