Unrevealing the translational reprogramming of root cells during nitrogen fixing symbiosis

TRAUBENIK, SOLEDAD; REYNOSO, MAURICIO; HOBECKER, KAREN; HUMER, MAUREEN; BAILEY-SERRES, JULIA; BLANCO, FLAVIO; ZANETTI, MARÍA EUGENIA

Congreso; XVIII International Congress Molecular Plant-Microbe Interactions; 2019

Legumes plants have acquired the ability to establish a nitrogen fixing symbiosis with rhizobial bacteria during evolution. The establishment of this symbiotic interaction requires the formation of a new lateral root organ, the nodule, and changes in epidermal cells that will allow the rhizobia to infect the root tissue. The activation and coordination of these two genetic programs requires the reprogramming of root cells for symbiosis, which is accompanied by dramatic alterations in gene expression. Regulation of gene expression occurs at different tiers, including transcriptional, co-transcriptional and post-transcriptional events. Our studies have been focused on the co- and post-transcriptional events, including alternative splicing, translation and non-coding RNA-mediated repression. By combining TRAP (Translating Ribosome Affinity Purification) with ribosome footprinting, we have profiled the root translatome at early stages of the legume-rhizobia symbiosis. We have found that translation of hundreds of transcripts is finely regulated and not necessarily correlated with steady-state transcript levels. Transcripts with altered translational status include protein-coding and non-coding RNAs, some of which exhibited cell-specific regulation. Transcript variants produced by either alternative splicing or alternative cleavage and polyadenylation are also tightly regulated at translational level. Using molecular and genetic approaches we have revealed that these translationally regulated transcripts play crucial roles in the establishment of a successful nitrogen fixing symbiosis.