Legume–rhizobia siRNA-mediated communication in symbiosis. – SymbiSIL

Plants of the legume (Fabaceae) family establish a root endosymbiotic interaction of high agronomical and ecological importance with soil bacteria collectively named rhizobia. This interaction culminates in the formation of the dinitrogen (N2) fixing nodule where bacteria differentiate into bacteroids to convert atmospheric N2 into ammonia. The communication between these symbionts is sophisticated and may involve exchange of small non-coding RNAs (sRNA). In this project, we will explore the impact of plant sRNAs, notably those deriving from transposons and associated to RNA-dependent DNA methylation, on the reprogramming of rhizobial gene expression during the rhizobium-legume symbiosis. We will assess the ability of some of these plant siRNA-mediated regulations to control bacteroid differentiation, N2 fixation, and persistence inside nodules. Results obtained may open wide perspectives for improving host-bacteria communication and symbiotic efficiency, and will have implications for other eukaryotic symbioses beyond legume plants.