Characterization of non-coding RNAs in root exudates and effects on Plant Growth-Promoting Rhizobacteria

International audience

English. Roots play a crucial role in shaping interactions between plants and their surrounding soil microbiota through secreting a wide range of bioactive compounds. Exuded metabolites serve as essential signals that attract specific groups of beneficial microbes to roots that help plants to adapt and ensure their survival to changing environmental conditions. Molecular basis of this complex process remains partially deciphered. To understand whether host – soil microbe interactions occur through microRNAs transfer, we analyzed the molecular composition of root exudates collected from wheat, pea and rapeseed exposed to drought stress and perfluorooctanoic acid (PFOA) contaminated soil and explored their potential effect on soil bacteria growth. A total of 56 miRNAs sequences in control and stressed plant samples were identified by using next generation sequencing (NGS). Bioanalyzer and qPCR analysis validated microRNAs expression and showed highest amounts in exudates collected under stress conditions. Bioinformatics approaches also revealed that detected miRNAs were predicted to target genes involved in the regulation of glycolysis, cell wall formation pathways and growth of two Plant growth-promoting rhizobacteria (PGPR), Pseudomonas fluorescens and Bacillus subtilis. In the same way, in vitro culture assay evidenced stimulatory effect of these microRNAs on growth of both tested strains following 4 hours incubation. Biofilm formation and carbon metabolic activity assay are in progress and may help to confirm regulatory function of microRNAs. This study offers new insights that microRNAs as an emerging class of root exudates have the capacity to affect microbial associated process in the rhizosphere to improve plant fitness in perturbed ecosystems.