Nuclear gene silencing directs reception of long-distance mRNA silencing in Arabidopsis

Brosnan, C. A., Mitter, N., Christie, M., Smith, N. A., Waterhouse, P. M., & Carroll, B. J. (2007) Nuclear gene silencing directs reception of long-distance mRNA silencing in Arabidopsis. Proceedings of the National Academy of Sciences of the United States of America, 104(37), pp. 14741-14746.

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Abstract

In plants, silencing of mRNA can be transmitted from cell to cell and also over longer distances from roots to shoots. To investigate the long-distance mechanism, WT and mutant shoots were grafted onto roots silenced for an mRNA. We show that three genes involved in a chromatin silencing pathway, NRPD1a encoding RNA polymerase IVa, RNA-dependent RNA polymerase 2 (RDR2), and DICER-like 3 (DCL3), are required for reception of long-distance mRNA silencing in the shoot. A mutant representing a fourth gene in the pathway, argonaute4 (ago4), was also partially compromised in the reception of silencing. This pathway produces 24-nt siRNAs and resulted in decapped RNA, a known substrate for amplification of dsRNA by RDR6. Activation of silencing in grafted shoots depended on RDR6, but no 24-nt siRNAs were detected in mutant rdr6 shoots, indicating that RDR6 also plays a role in initial signal perception. After amplification of decapped transcripts, DCL4 and DCL2 act hierarchically as they do in antiviral resistance to produce 21- and 22-nt siRNAs, respectively, and these guide mRNA degradation. Several dcl genotypes were also tested for their capacity to transmit the mobile silencing signal from the rootstock. dcl1-8 and a dcl2 dcl3 dcl4 triple mutant are compromised in micro-RNA and siRNA biogenesis, respectively, but were unaffected in signal transmission. © 2007 by The National Academy of Sciences of the USA.

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ID Code: 65794
Item Type: Journal Article
Refereed: Yes
Additional Information: Open Access on publisher website via author-paid open access option
Additional URLs:
Keywords: Epigenetics, Long-distance signaling, RNA interference, dicer, DICER like 3 protein, DNA directed RNA polymerase, messenger RNA, microRNA, protein DCL2, protein DCL4, RNA directed RNA polymerase, RNA directed RNA polymerase 2, small interfering RNA, unclassified drug, ago4 gene, Arabidopsis, article, chromatin structure, dcl1 8 gene, dcl2 dcl3 dcl4 gene, gene, gene amplification, gene silencing, genotype, mutator gene, nonhuman, nrpd1a gene, nucleotide sequence, plant, plant root, priority journal, RNA analysis, RNA degradation, Arabidopsis Proteins, Cell Nucleus, Epigenesis, Genetic, Models, Biological, Mutation, Ribonuclease III, RNA Replicase, RNA, Messenger, RNA, Small Interfering, Iva
DOI: 10.1073/pnas.0706701104
ISSN: 0027-8424
Divisions: Current > Schools > School of Earth, Environmental & Biological Sciences
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: National Academy of Sciences of the United States of America
Deposited On: 07 Jan 2014 23:40
Last Modified: 07 Jan 2014 23:44

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