RNA silencing movement in plants

Kalantidis, Kriton; Schumacher, Heiko; Alexiadis, Tasos; Helm, Jutta Maria

doi:10.1042/bc20070079

Cited by 127 publications

(105 citation statements)

References 119 publications

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“…SGS3 is thought to stabilize precursor RNAs, allowing them to be targets of RDR6 activity (23). Among other things, RDR6/SGS3 activity is required for virus-induced gene silencing-directed DNA methylation and long-range systemic silencing (22,24). It is also essential for the tasiRNA pathway, which bears distinct similarities to Muk-induced transacting silencing of MuDR (25).…”

Section: Resultsmentioning

confidence: 99%

Epigenetic reprogramming during vegetative phase change in maize

Freeling²,

Lisch³

2010

Proc. Natl. Acad. Sci. U.S.A.

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An important step during plant development is the transition from juvenile to adult growth. It is only after this transition that plants are reproductively competent. Given the great danger that transposon activity represents to the germ line, this may also be an important period during development with respect to transposon regulation and silencing. We demonstrate that a change in expression of a key component of the RNA silencing pathway is associated with both vegetative phase change and shifts in epigenetic regulation of a maize transposon.primary problem facing all organisms is the proliferation of selfish DNA in the form of transposable elements. This proliferation is predominantly held in check via epigenetic silencing (1, 2). Recent work in both plants and animals suggests that there are key points in development during which silencing of transposons is reinforced (3, 4). In animals, mechanisms to reinforce silencing appear to be largely confined to the germ line. Indeed, recent work in Drosophila suggests that transposon regulation and germ-line differentiation are intimately connected through the activity of PIWI proteins, which are involved in processing of specific classes of small RNAs, most of which are derived from transposons (5). However, plants face a distinct challenge because, unlike animals, they do not have a sequestered germ line. Thus, changes in transposon activity in somatic tissues can be transmitted to subsequent generations (6). From this perspective, an important stage in plant development is the transition from the juvenile phase to the adult phase of growth, for it is only after this transition that plants become reproductively competent (7). Here we provide evidence that this transition in maize is associated with a transient loss of expression of a key regulator of the trans-acting siRNA (tasiRNA) pathway and with dramatic changes in epigenetic regulation of a transposon as it is being silenced.Our model for plant transposon silencing is the MuDR element of maize. Heritable silencing of MuDR transposons can be triggered by a naturally occurring derivative of MuDR called Mu killer (Muk) (8). MuDR elements are flanked by two long terminal inverted repeats (TIRs) that carry the promoters for two convergently transcribed genes, mudrA and mudrB (Fig. 1A). The mudrA gene encodes the putative transposase; mudrB is a helper gene required for insertion of Mu elements in maize (9). Muk produces a long, double-stranded RNA (dsRNA) hairpin transcript with homology to mudrA (8, 10). Silencing of MuDR by Muk is triggered by a simple genetic cross between a plant carrying MuDR and one carrying Muk. Silencing of MuDR by Muk is associated with the amplification of substantial quantities of small RNAs homologous to mudrA in the second leaf of developing seedlings (10). By the immature ear stage of these F1 (MuDR;Muk) plants, mudrA becomes transcriptionally silenced, and some cytosines within the TIR immediately adjacent to mudrA (TIRA) become methylated. The natural MuDR;Muk system allows us to t...

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Section: Resultsmentioning

confidence: 99%

Epigenetic reprogramming during vegetative phase change in maize

Freeling²,

Lisch³

2010

Proc. Natl. Acad. Sci. U.S.A.

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“…The siRNAs are non-cell autonomous and are indeed very abundant in phloem sap where they act on systemic silencing [176]. The presence of several miRNAs, usually considered as cell autonomous [177] is perhaps more surprising.…”

Section: Rnas Species and Traffickingmentioning

confidence: 99%

Phloem sap intricacy and interplay with aphid feeding

Dinant

Bonnemain

Girousse

et al. 2010

Comptes Rendus. Biologies

147

118

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ARTICLE INFO ABSTRACT Keywords:Stylectomy Phloem exudation Phloem sap Sieve element EPG Transporters Plant defenceAphididae feed upon the plant sieve elements (SE), where they ingest sugars, nitrogen compounds and other nutrients. For ingestion, aphid stylets penetrate SE, and because of the high hydrostatic pressure in SE, phloem sap exudes out into the stylets. Severing stylets to sample phloem exudates (i.e. stylectomy) has been used extensively for the study of phloem contents. Alternative sampling techniques are spontaneous exudation upon wounding that only works in a few plant species, and the popular EDTA-facilitated exudation technique. These approaches have allowed fundamental advances on the understanding of phloem sap composition and sieve tube physiology, which are surveyed in this review. A more complete picture of metabolites, ions, proteins and RNAs present in phloem sap is now available, which has provided large evidence for the phloem role as a signalling network in addition to its primary role in partitioning of photo-assimilates. Thus, phloem sap sampling methods can have remarkable applications to analyse plant nutrition, physiology and defence responses. Since aphid behaviour is suspected to be affected by phloem sap quality, attempts to manipulate phloem sap content were recently undertaken based on deregulation in mutant plants of genes controlling amino acid or sugar content of phloem sap. This opens up new strategies to control aphid settlement on a plant host. importantes pour l'analyse de la composition de la séve et la physiologie des tubes criblés. Un tableau assez complet des metabolites, des ions, des hormones, des protéines et des ARN presents dans la séve du phloéme est désormais disponible. Ces avancées ont largement étayé le role du phloéme comme réseau de signalisation, en plus de son role central dans la repartition des photo-assimilats. Ces méthodes d'echantillonnage de la séve élaborée ont aussi des applications potentielles remarquables pour l'analyse de la nutrition, la physiologie et les reactions de defense des plantes. Plusieurs études ayant suggéré que la qualité de la séve phloémienne pouvait affecter le comportement alimentaire des pucerons, des tentatives de manipulation de la composition de la séve phloémienne ont été engagées, basées sur la deregulation des genes controlant la teneur en acides amines ou en sucres de la séve, dans les plantes transgéniques. De telles approches ouvrent des strategies nouvelles pour limiter le développement des pucerons sur leur plante hote et ainsi leur nuisibilité. RESUME

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“…Indeed, accumulation of cucumber mosaic cucumovirus (CMV) is markedly increased in Arabidopsis rdr6 or sgs3 mutants, indicating that amplification of RNA silencing plays an important role in antiviral defense (Wang et al, 2011). Furthermore, amplification of RNA silencing has been implicated in the spread of an RNA silencing signal (Himber et al, 2003;Schwach et al, 2005;Kalantidis et al, 2008). This signal can move between cells via plasmodesmata and over long distances through phloem, triggering sequence-specific RNA silencing in distant tissues (Voinnet and Baulcombe, 1997;Voinnet et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor

et al. 2014

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RNA silencing plays an important antiviral role in plants and invertebrates. To counteract antiviral RNA silencing, most plant viruses have evolved viral suppressors of RNA silencing (VSRs). TRIPLE GENE BLOCK PROTEIN1 (TGBp1) of potexviruses is a well-characterized VSR, but the detailed mechanism by which it suppresses RNA silencing remains unclear. We demonstrate that transgenic expression of TGBp1 of plantago asiatica mosaic virus (PlAMV) induced developmental abnormalities in Arabidopsis thaliana similar to those observed in mutants of SUPPRESSOR OF GENE SILENCING3 (SGS3) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6) required for the trans-acting small interfering RNA synthesis pathway. PlAMV-TGBp1 inhibits SGS3/ RDR6-dependent double-stranded RNA synthesis in the trans-acting small interfering RNA pathway. TGBp1 interacts with SGS3 and RDR6 and coaggregates with SGS3/RDR6 bodies, which are normally dispersed in the cytoplasm. In addition, TGBp1 forms homooligomers, whose formation coincides with TGBp1 aggregation with SGS3/RDR6 bodies. These results reveal the detailed molecular function of TGBp1 as a VSR and shed new light on the SGS3/RDR6-dependent double-stranded RNA synthesis pathway as another general target of VSRs.

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RNA silencing movement in plants

Cited by 127 publications

References 119 publications

Epigenetic reprogramming during vegetative phase change in maize

Epigenetic reprogramming during vegetative phase change in maize

Phloem sap intricacy and interplay with aphid feeding

In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor

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