DYNAMIC REGULATION OF THE Medicago truncatula TRANSLATOME MEDIATED BY LONG NON CODING RNAs DURING ROOT NODULE SYMBIOSIS

TRAUBENIK S, REYNOSO M, ROSE B, TOWN C, BLANCO F, ZANETTI M E

Buenos Aires

Jornada; XVIII Jornadas Anuales Multidisciplinarias-?Codificar o no codificar: rol de ARN no codificantes en la fisiología y la patología?; 2016

Sociedad Argentina de Biologia

Regulation of gene expression occurs at multiple levels within eukaryotic cells, including chromatin-based, transcriptional and post-transcriptional events. The development of techniques associated with transcriptomics has led to the use of steady-state levels of mRNA as a criterion to select and study genes with a possible implication in agronomically important characters. This strategy approach has excluded levels of post-transcriptional regulation, such as the rapid response through the translational activation of pre-existing mRNAs. We have previously shown that genes involved in the legume root symbiosis are regulated at the level of their association with the translation machinery. Here, we used Translating Ribosome Affinity Purification (TRAP) combined with RNA-seq to characterize the mRNA and non-coding RNA populations associated to polysomes (referred to as the translatome). The characterization of dynamic changes in the translatome of Medicago truncatula roots at early stages of the root nodule symbiosis led us to the identification of mRNAs that significantly increased or decreased their levels of association with polysomes in response to the presence of rhizobia, some of which play essential roles in nodulation (e.g., Nodule Inception, Nuclear factor YA1, pectate lyase, SINA and NCR secreted peptides). We have also identified a group of mRNAs that are either up- or down-regulated at the translational level, which encode proteins that participate in epigenetic and post-transcriptional regulation. In addition, a significant number of long non-coding RNAs (lncRNAs) that change their association with polysomes in response to rhizobial infection were identified. These lncRNAs, associated with the translational machinery, may act repressing or activating the translation of its mRNA targets or encoding functional small peptides, contributing to the reprogramming of root cells during early stages of the symbiotic interaction.