Dynamic regulation of the Medicago truncatula translatome during root nodule symbiosis

SOLEDAD TRAUBENIK, MAURICIO REYNOSO, MARCOS LANCIA, FLAVIO BLANCO AND MARÍA EUGENIA ZANETTI

Austin Texas

Congreso; Plant Biology 2016; 2016

American Society of Plant Bology

Regulation of gene expression occurs at multiple levels within eukaryotic cells, including chromatin-based, transcriptional and post-transcriptional events. The rise of the 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 approach has excluded levels of post-transcriptional regulation, associated with a rapid response through the 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 allow the characterization of mRNA and sRNA populations associated to polysomes (referred 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, some of which play essential roles in nodulation (e.g., pectate lyase, SINA and NCR secreted peptides). We have also identified a group of genes either up- or down-regulated at translational levels that participate in pre-mRNA splicing, 3´-processing of the pre-RNA, RNA-mediated post-transcriptional gene silencing, miRNA-mediated repression and mRNA turnover, as well as genes involved in epigenetic and transcriptional regulation. The differential expression of these genes was confirmed by RT-PCR and they are being analyzed by functional genomics.