Résumé
The mechanisms involved in the stimulation of plant growth by plant-growth-promoting rhizobacteria (PGPR) remained obscure until the very end of twentieth century. In the last decade, investigations on the plant partner of plant–PGPR interaction have begun to unveil the diversity and complexity of mechanisms behind growth promotion. These studies that used the model plant Arabidopsis to identify plant signaling pathways modulated by PGPR provide new paradigms on how rhizobacteria modify plant development and nutrition. This chapter presents insights on PGPR-elicited developmental and nutritional regulations that have been obtained. Overall, the emerging picture is the concomitant elicitation of a variety of regulatory mechanisms that only begin to be identified as mediators of plant responses. It leaves large gaps in our knowledge, especially on primary PGPR targets and molecular events linking PGPR with individual plant regulatory pathways, and on the integration of these regulations within a probably complex cross talk network.