GSE27093
High-throughput pyrosequencing of endogenous small RNAs in O. Europaea
Small RNAs of 20 to 25 nucleotides in length maintain genome integrity and control gene expression in a multitude of developmental and physiological processes. Despite RNA silencing has been primarily studied in model plants, the advent of high-throughput sequencing technologies has enabled profiling of the small RNA component of more than 40 plant species. Here, use deep sequencing and molecular methods to report the first inventory of small RNAs in olive (Olea europaea). Small RNAs of 24 nts dominate the small RNA transcriptome and atypically accumulate to levels never seen in other plant species, suggesting an active role of heterochromatin silencing in the maintenance and integrity of its large genome. By contrast, small RNAs of 20 to 22 nts were poorly represented in the population at levels lower than those found in most plant species tested. A total of 14 known miRNA families were identified in two libraries prepared from growing and dormant lateral buds. We found that some known miRNAs showed tissue- and/or developmental-specific expression. Also, seven novel, olive-specific miRNA candidates were found in our sequenced set of which 1 were supported by their star strands. Potential precursors for these miRNA candidates with intramolecular folding capacities were found in the olive EST database. Target mRNAs of conserved miRNAs and new olive-specific miRNA were computationally predicted among the olive EST collection and experimentally validated through endonucleolytic cleavage assays. Overall design: Two samples analyzed: growing (juvenile) and dormant (adult) lateral buds from the progeny of a genetic cross between the Picual and Arbequina olive varieties