Proteome Analysis Reveals a Significant Host-Specific Response in Rhizobium leguminosarum bv. viciae Endosymbiotic Cells

The symbiosis with Rhizobium allows nitrogen fixation in legume root nodules, a key contribution of soil bacteria to a more sustainable agriculture by reducing the use of nitrogen fertilizers. In order to study the adaptation of the microsymbionts to the plant cell environment, a research group at CBGP in collaboration with researchers from CBM-SO has carried out a comparative proteome analysis of Rhizobium bacteroids induced by the same strain in pea and lentil nodules. The results obtained indicate that legume host affects the presence of multiple rhizobial proteins in bacteroids, including transcriptional regulators, stress response proteins and others. Consistently with this, different profiles of plant-derived NCR peptides were found in pea vs. lentil bacteroids. These peptides might be modulating Rhizobium response under intracellular conditions in the nodule. These data suggest a fine-tuning of bacterial gene expression to adapt to specific conditions provided by the plant. This work will allow a better understanding of the bacteria-plant dialogue in this symbiosis and will contribute to the development of efficient procedures to improve the specificity of Rhizobium performance as legume inoculants.