title: Biogenesis of diverse plant phasiRNAs involves an miRNA-trigger and Dicer-processing.
abstract: It has been almost 30 years since RNA interference (RNAi) was shown to silence genes via double-stranded RNAs (dsRNAs) in Caenorhabditis elegans (Fire et al. 1998). 20-30-nucleotide (nt) small non-coding RNAs are a key element of the RNAi machinery. Recently, phased small interfering RNAs (phasiRNAs), small RNAs that are generated from a long RNA precursor at intervals of 21 to 26-nt, have been identified in plants and animals. In Drosophila, phasiRNAs are generated by the endonuclease, Zucchini (Zuc), in germlines. These phasiRNAs, known as one of PIWI-interacting RNAs (piRNAs), mainly repress transposable elements. Similarly, reproduction-specific phasiRNAs have been identified in the family Poaceae, although DICER LIKE (DCL) protein-dependent phasiRNA biogenesis in rice is distinct from piRNA biogenesis in animals. In plants, phasiRNA biogenesis is initiated when 22-nt microRNAs (miRNAs) cleave single-stranded target RNAs. Subsequently, RNA-dependent RNA polymerase (RDR) forms dsRNAs from the cleaved RNAs, and dsRNAs are further processed by DCLs into 21 to 24-nt phasiRNAs. Finally, the phasiRNAs are loaded to ARGONAUTE (AGO) proteins to induce RNA-silencing. There are diverse types of phasiRNA precursors and the miRNAs that trigger the biogenesis. Their expression patterns also differ among plant species, suggesting that species-specific combinations of these triggers dictate the spatio-temporal pattern of phasiRNA biogenesis during development, or in response to environmental stimuli.
authors.affiliation: Science and Technology Group, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Kunigami-gun, Okinawa, 904-0495, Japan. reina.komiya@oist.jp.
authors.forename: Reina
authors.initials: R
authors.lastname: Komiya
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism*; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism*
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering; D012324:RNA-Dependent RNA Polymerase; D043244:Ribonuclease III
keywords: 22-nt miRNAs; ARGONAUTE; DCL-processing; Reproduction; phasiRNAs; tasiRNAs