CONICET | Buscador de Institutos y Recursos Humanos

MiRNAs areendogenous small RNAs of 20-22 nt that play a role as post-transcriptional generegulators. They recognize target sequences in the other RNAs by basecomplementarity and guide them to cleavage or translational arrest. MiRNAs aregenerated from longer precursors that harbor fold-back structure with the miRNAlocated in one of their arms. In plants, miRNAs precursors are processed in thenuclei by a complex including DICER-LIKE1 (DCL1). This complex recognizesstructural determinants in the precursors to produce cuts that release themature miRNAs. To gain insights into the miRNA processing, we performed arandom mutagenesis to improve the biogenesis of a plant miRNA. We focused on Arabidopsis miR172, amiRNA that regulates flowering time and flower patterning. We found that asingle change in the MIR172 precursor can significantly improve the biogenesisof small RNA. We identified and characterized hot spots in MIRNA precursors,where small changes significantly affect the efficiency oft he miRNA biogenesisin plants. WE extended our results to several precursors including MIR156/7,MIR171, MIR164 and MIR164/5. The results provide new insights into themolecular basis of miRNA processing in plants.