title: A highly specific microRNA-mediated mechanism silences LTR retrotransposons of strawberry.
abstract: Small RNAs are involved in a plethora of functions in plant genomes. In general, transcriptional gene silencing is mediated by 24-nucleotide siRNAs and is required for maintaining transposable elements in a silenced state. However, microRNAs are not commonly associated with transposon silencing. In this study, we performed small RNA transcriptome and degradome analyses of the Rosaceae model plant Fragaria vesca (the woodland strawberry) at the genome-wide level, and identified miRNA families and their targets. We report a highly specific mechanism of LTR retrotransposon silencing mediated by an abundant, ubiquitously expressed miRNA (fve-miR1511) generated from a single locus. This miRNA specifically targets LTR retroelements, silencing them post-transcriptionally by perfectly pairing to the highly conserved primer binding site for methionyl initiator tRNA that is essential for reverse transcription. We investigated the possible origins of this miRNA, and present evidence that the pre-miR1511 hairpin structure probably derived from a locus coding for tRNA(iM) (et) through a single microinversion event. Our study shows that this miRNA targets retrotransposons specifically and constitutively, and contributes to features such as genome stability, size and architecture in a far more direct way than previously thought.
authors.affiliation: Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy.
authors.forename: Nada
authors.initials: N
authors.lastname: Šurbanovski
authors.affiliation: Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Brilli
authors.affiliation: Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy.
authors.forename: Mirko
authors.initials: M
authors.lastname: Moser
authors.affiliation: Functional Genomics, Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, San Michele all' Adige, 38010, Italy.
authors.forename: Azeddine
authors.initials: A
authors.lastname: Si-Ammour
mesh_terms: D004722:Endoribonucleases; D031985:Fragaria / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D009097:Multienzyme Complexes; D011117:Polyribonucleotide Nucleotidyltransferase; D020365:RNA Helicases; D018749:RNA, Plant / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D020079:Terminal Repeat Sequences / Q000235:genetics; D059467:Transcriptome
chemical_list: D035683:MicroRNAs; D009097:Multienzyme Complexes; D018749:RNA, Plant; D034741:RNA, Small Interfering; D018626:Retroelements; C111244:degradosome; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases; D020365:RNA Helicases
keywords: Degradome; Fragaria vesca; LTR retrotransposon; miRNA; primer binding site; tRNA