Identification of Novel and Known miRNAs and Their Targets in Pinus spp and Eucalyptus globulus

Pines (Pinus spp) and Eucalyptus globulus are important species in the Portuguese forest plantations, being used for timber, pulp, and paper production. Due to their economic and ecological importance several transcriptomic and proteomic resources were made available and allowed to identify major molecular players involved in xylogenesis and biotic and abiotic responses. However, the understanding of molecular mechanisms regulating xylogenesis and these responses, including the post-regulation mediated by miRNAs, are still incipient. MicroRNAs are small non-coding RNAs (21-24bp), being key post-transcriptional regulators of gene expression in different developmental and stress-related biological processes. In plants miRNAs act by down-regulating mRNA expression either by cleavage or by translational repression, through direct base-pairing to target sites in mRNAs.

In order to get new insights on these post-transcriptional regulation mechanisms we are developing resources to study the post-transcriptional regulation mediated by miRNAs of Pinus pinaster, P. sylvestris and Eucalyptus globulus. A catalog of miRNA of xylem, phloem, and leaves tissues were produced, using smallRNA-Seq data and appropriated bioinformatics analysis methodologies. In addition, degradome libraries for those tissues were prepared and used to identify their target genes. Here we present the results of our work, shedding light on identification of miRNAs and their targets in these important tree species in Europe.