AtRLI2 is an Endogenous Suppressor of RNA Silencing

Sarmiento, Cecilia; Nigul, Lenne; Kazantseva, Jekaterina; Buschmann, Marju; Truve, Erkki

doi:10.1007/s11103-005-0001-8

Cited by 40 publications

(67 citation statements)

References 48 publications

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“…Northern blot detection of TRSV-specific RNAs was carried out using a digoxygenin-labelled probe, synthesized by PCR from the above-mentioned cDNA clone, according to the manufacturer's instructions (Roche). Analysis of TRSV-specific small interfering RNAs (siRNAs) was carried out according to Sarmiento et al (2006) using 30 mg total RNA from N. benthamiana. The radioactive probe was a 32 P-labelled in vitro transcript corresponding to the abovementioned cDNA clone of the viral RNAs.…”

Section: Methodsmentioning

confidence: 99%

Effects of viral silencing suppressors on tobacco ringspot virus infection in two Nicotiana species

Siddiqui

Sarmiento

Kiisma

et al. 2008

Journal of General Virology

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This study investigated the effects of silencing suppressors derived from six different viruses (P1, P19, P25, HcPro, AC2 and 2b), expressed in transgenic Nicotiana tabacum and Nicotiana benthamiana plants, on the infection pattern of tobacco ringspot virus (TRSV) potato calico strain. In N. benthamiana, this virus produced an initial infection with severe systemic symptoms, but the infection was strongly reduced within a few weeks as the plant recovered from the infection. P25 and HcPro silencing suppressors effectively prevented recovery in this host, allowing continuous accumulation of the viral RNA as well as of the virus-specific small interfering RNAs, in the systemically infected leaves. In the P1-, P19-, AC2-or 2b-expressing transgenic N. benthamiana, the recovery was not complete. Susceptibility of N. tabacum to this virus was temperature sensitive. At lower temperatures, up to 25 6C, the plants became systemically infected, but at higher temperatures, the infections were limited to the inoculated leaves. In these preventative conditions, all silencing suppressor transgenes (except P25, which was expressed at very low levels) allowed the establishment of systemic infections. Very strong and consistent systemic infections were observed in HcPro-and AC2-expressing plants.

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Section: Methodsmentioning

confidence: 99%

Effects of viral silencing suppressors on tobacco ringspot virus infection in two Nicotiana species

Siddiqui

Sarmiento

Kiisma

et al. 2008

Journal of General Virology

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“…Furthermore, mutations in ENHANCED SILENCING PHENOTYPE (ESP) genes involved in RNA processing and 39 end formation enhance the RNA silencing of a potato virus X phytoene desaturase amplicon, presumably by allowing RNAs with aberrant 39 termini to enter the PTGS pathway (Herr et al, 2006). In addition, the Arabidopsis putative RNase L inhibitor RLI2 was shown to suppress transgenemediated silencing when expressed at high levels transiently in Nicotiana benthamiana (Sarmiento et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Arabidopsis FIERY1, XRN2, and XRN3 Are Endogenous RNA Silencing Suppressors

et al. 2007

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The eukaryotic defense response posttranscriptional gene silencing (PTGS) is directed by short-interfering RNAs and thwarts invading nucleic acids via the RNA slicing activity of conserved ARGONAUTE (AGO) proteins. PTGS can be counteracted by exogenous or endogenous suppressors, including the cytoplasmic exoribonuclease XRN4, which also degrades microRNA (miRNA)-guided mRNA cleavage products but does not play an obvious role in development. Here, we show that the nuclear exoribonucleases XRN2 and XRN3 are endogenous PTGS suppressors. We also identify excised MIRNA loops as templates for XRN2 and XRN3 and show that XRN3 is critical for proper development. Independently, we identified the nucleotidase/ phosphatase FIERY1 (FRY1) as an endogenous PTGS suppressor through a suppressor screen in a hypomorphic ago1 genetic background. FRY1 is one of six Arabidopsis thaliana orthologs of yeast Hal2. Yeast hal2 mutants overaccumulate 39-phosphoadenosine 59-phosphate, which suppresses the 59!39 exoribonucleases Xrn1 and Rat1. fry1 mutant plants recapitulate developmental and molecular characteristics of xrn mutants and likely restore PTGS in ago1 hypomorphic mutants by corepressing XRN2, XRN3, and XRN4, thus increasing RNA silencing triggers. We anticipate that screens incorporating partially compromised silencing components will uncover additional PTGS suppressors that may not be revealed using robust silencing systems.

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“…In addition, an inhibitor protein of A. thaliana RNase L activity, called RLI2, was also described as having a silencing suppressor activity when expressed at high levels in transgenic N. benthamiana [123]. Another known endogenous suppressor, the A. thaliana exoribonuclease XRN4, suppresses silencing by promoting the degradation of aberrant, uncapped RNAs that constitute possible templates for an RNA dependent RNA polimerase (RdRP) pathway involved in silencing.…”

Section: Endogenous Suppressorsmentioning

confidence: 99%