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Comparative Study
. 2011 Apr;39(7):2880-9.
doi: 10.1093/nar/gkq1240. Epub 2010 Dec 5.

Comparative Analysis of Non-Autonomous Effects of tasiRNAs and miRNAs in Arabidopsis Thaliana

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Free PMC article
Comparative Study

Comparative Analysis of Non-Autonomous Effects of tasiRNAs and miRNAs in Arabidopsis Thaliana

Felipe Fenselau de Felippes et al. Nucleic Acids Res. .
Free PMC article

Abstract

In plants, small interfering RNAs (siRNAs) can trigger a silencing signal that may spread within a tissue to adjacent cells or even systemically to other organs. Movement of the signal is initially limited to a few cells, but in some cases the signal can be amplified and travel over larger distances. How far silencing initiated by other classes of plant small RNAs (sRNAs) than siRNAs can extend has been less clear. Using a system based on the silencing of the CH42 gene, we have tracked the mobility of silencing signals initiated in phloem companion cells by artificial microRNAs (miRNA) and trans-acting siRNA (tasiRNA) that have the same primary sequence. In this system, both the ta-siRNA and the miRNA act at a distance. Non-autonomous effects of the miRNA can be triggered by several different miRNA precursors deployed as backbones. While the tasiRNA also acts non-autonomously, it has a much greater range than the miRNA or hairpin-derived siRNAs directed against CH42, indicating that biogenesis can determine the non-autonomous effects of sRNAs. In agreement with this hypothesis, the silencing signals initiated by different sRNAs differ in their genetic requirements.

Figures

Figure 1.
Figure 1.
Spreading of miRNA-triggered silencing from phloem companion cells. (A) SUC2:amiR-SUL and SUC2:siR-SUL plants present similar bleaching patterns. (B) UV-induced red chlorophyll autofluorescence is suppressed in bleached areas, which appear light green in a SUC2:amiR-SUL leaf. Arrows point to leaf veins. (C) SUC2:amiR-SUL SUC2:3xYFP leaf. Top, visible light; bottom, UV fluorescence. Bright green YFP signal is more restricted than the bleached areas that are dark. (D) Comparison of mild and severely bleached plants. A single leaf is shown in detail. (E) sRNA blots probed with an oligonucleotide specific for amiR-SUL (SUL) or a CH42 fragment (CH42 frag). U6 was used as loading control.
Figure 2.
Figure 2.
Confirmation of amiR-SUL-triggered silencing. (A) amiR-SUL production in dcl234 triple mutant background. (B) RDR6-independent spreading of amiR-SUL-triggered silencing. (C) sRNA blots. Probes are indicated on the right. siR255 production is RDR6 and DCL4-dependent, siR1003 is DCL3-dependent but RDR6-independent. MiR159 was used as an additional control. Note characteristic leaf shape of rdr6 and dcl234 mutants in (A) and (B).
Figure 3.
Figure 3.
Effect of MIRNA backbone on spreading of the silencing signal. (A) Whole-rosette phenotypes of plants expressing amiR-SUL from different precursors, with promoters indicated on the left. (B) Precursor expression monitored by RT–PCR with β-TUBULIN-2 (TUB) as control. (C) sRNA blots.
Figure 4.
Figure 4.
Non-autonomous effects of of atasiR-SUL. (A) Whole-rosette phenotype of SUC2:atasiR-SUL_1c. (B) sRNA blots. MiR173, which triggers TAS1 processing, was used as an additional control.
Figure 5.
Figure 5.
Secondary sRNAs at the CH42 locus. (A) Diagram of CH42 locus. Exons are indicated as thick lines. Regions targeted by primary sRNAs from siR-SUL and amiR/atasiR-SUL transgenes are shown. (B) Small RNA populations at the CH42 locus. About 19–26 nt sRNAs, with a maximum of two mismatches (as in amiR/atasi-SUL), are shown. See Supplementary Figure S6 for perfect-match sRNAs only. Grey regions indicate origin of primary siR-SUL and amiR/atasiR-SUL, respectively.
Figure 6.
Figure 6.
Differential genetic requirements for non-autonomous effects of amiR-SUL and atasiR-SUL initiated silencing. (A) Whole-rosette phenotypes. (B) sRNA blots.

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References

    1. Mallory AC, Vaucheret H. Functions of microRNAs and related small RNAs in plants. Nat. Genet. Suppl. 2006;38:S31–S36. - PubMed
    1. Vazquez F. Arabidopsis endogenous small RNAs: highways and byways. Trends Plant Sci. 2006;11:460–468. - PubMed
    1. Chapman EJ, Carrington JC. Specialization and evolution of endogenous small RNA pathways. Nat. Rev. Genet. 2007;8:884–896. - PubMed
    1. Lu XY, Huang XL. Plant miRNAs and abiotic stress responses. Biochem. Biophys. Res. Commun. 2008;368:458–462. - PubMed
    1. Chuck G, Candela H, Hake S. Big impacts by small RNAs in plant development. Curr. Opin. Plant Biol. 2009;12:81–86. - PubMed

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