A Promiscuity Locus Confers Nodulation with Rhizobia from Five Different Genera.

Legumes acquire access to atmospheric nitrogen through nitrogen fixation by rhizobia in root nodules. Rhizobia are soil-dwelling bacteria and there is a tremendous diversity of rhizobial species in different habitats. From the legume perspective, host range is a compromise between the ability to colonize new habitats, in which the preferred symbiotic partner may be absent, and guarding against infection by suboptimal nitrogen fixers. Here, we investigate natural variation in rhizobial host range across species. We find that is considerably more promiscuous than , represented by the Gifu accession, in its interactions with rhizobia. This promiscuity allows to form nodules with , , , , and species that represent five distinct genera. Using recombinant inbred lines, we have mapped the Gifu/ promiscuity quantitative trait loci (QTL) to the same genetic locus regardless of rhizobial genus, suggesting a general genetic mechanism for symbiont-range expansion. The Gifu/ QTL now provides an opportunity for genetic and mechanistic understanding of promiscuous legume-rhizobia interactions. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.