Respective contributions of Arabidopsis DCL2 and DCL4 to RNA silencing. (3rd December 2014)

• Record Type: Journal Article
• Authors: Parent, Jean‐Sébastien; Bouteiller, Nathalie; Elmayan, Taline; Vaucheret, Hervé
• Is Part Of: Plant journal. Volume 81:Number 2(2015:Jan.)
• Page Start: 223
• Page End: 232
• Publication Date: 2014-12-03
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12720
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj1272-abs-0001"> <title>Summary</title> <p>Dicer proteins are central to the different mechanisms involving RNA interference. Plants have evolved multiple <italic>DICER‐LIKE</italic> (<italic>DCL</italic>) copies, thus enabling functional diversification. In Arabidopsis, DCL2 and DCL4 process double‐stranded RNA into 22 and 21 nucleotide small interfering (si)RNAs, respectively, and have overlapping functions with regards to virus and transgene silencing. Nonetheless, some studies have reported that <italic>dcl2</italic> or <italic>dcl4</italic> single mutations are sometimes sufficient to hinder silencing. To better dissect the role of DCL2 and DCL4, we analyzed silencing kinetics and efficiencies using different transgenic systems in single and double mutant backgrounds. The results indicate that DCL2 stimulates transitivity and secondary siRNA production through DCL4 while being sufficient for silencing on its own. Notably, silencing of 35S‐driven transgenes functions more efficiently in <italic>dcl4</italic> mutants, indicating that DCL4 mostly obscures DCL2 in wild‐type plants. Nonetheless, in a <italic>dcl4</italic> mutant compromised in phloem‐originating silencing, ectopically expressed DCL2 allows restoration of silencing, suggesting that DCL2 is not, or poorly, expressed in phloem. Remarkably, this ectopic DCL2 contribution to phloem‐originating silencing is dependent on the activity of RNA‐DEPENDENT RNA POLYMERASE6. These results indicate that, despite differences in the silencing activity of their small RNA products, DCL2 and DCL4 mostly act redundantly yet hierarchically when present simultaneously.</p> </abstract>