Mirnome Profiling Reveals Differential Mirnas Associated with Embryogenic Potential in the Somatic Embryogenesis of Araucaria Angustifolia

Transcript and proteomics studies in embryogenic cultures from Araucaria angustifolia, an endangered native Brazilian conifer with ecological and economic importance, have indicated a role for post-transcriptional regulation in this process. Here, we profiled the miRNA expression pattern using small RNA sequencing technology in two embryogenic cell lines, Responsive- and Blocked- (non-responsive)-to-ABA, of A. angustifolia. We identified 165 mature miRNAs, of which 143 were novel and 22 were conserved plant miRNAs. Seven miRNA conserved families were identified: miR156, miR169, miR394, miR482, miR536, miR1030, and miR1314. Most miRNAs were differentially expressed during the transition from proliferation to the maturation stage of somatic embryogenesis, suggesting that miRNAs play more important roles in the early somatic embryo development. Sixteen were exclusively expressed in RP-RM and 13 in BP-BM transition, indicating that miRNAs are also associated with embryogenic potential. A total of 98 potential target genes were found for 89 miRNAs, involved in post-transcriptional processes, transporters, defense response, sugar regulation, stress, ABA and auxin controlling and signaling, cell-to-cell communication, maintaining suspensor cell identity, brassinosteroids signaling, and cell division. Negative correlations of expression patterns between miRNAs and their targets were detected for miR1030-PRL1, miR1314-ADR1-Like, and Aang34-LRR modules, when analyzed by RT-qPCR. Taken together, our findings provide new insights into the regulatory roles of miRNAs and their target genes in the somatic embryogenesis of Brazilian pine.