Abstract
In Arabidopsis, micro (mi)RNAs and trans-acting (ta-si)RNAs synthesized directly or indirectly through the DICER-LIKE-1 (DCL1) ribonuclease have roles in patterning and hormonal responses, while DCL2,3,4-dependent small-interfering (si)RNAs are mainly involved in silencing of transposable elements and antiviral defense. Viral suppressors of RNA silencing (VSRs) produced by phytoviruses to counter plant defense may perturb plant developmental programs because of the collision of their inhibitory effects with the regulatory action of endogenous miRNAs and ta-siRNAs. This could explain the similar developmental aberrations displayed by Arabidopsis miRNA/ta-siRNA pathway mutants, including dcl1, and by some VSR-expressing plants. Nonetheless, the molecular bases for these morphological aberrations have remained mysterious, and their contribution to viral disease symptoms/virulence unexplored. The extent of VSR inhibitory actions to other types of endogenous small RNAs remains also unclear. Here, we present an in-depth analysis of transgenic Arabidopsis expressing constitutively HcPro, P19 and P15, three unrelated VSRs. We show that VSR expression has comparable, yet modest effects on known miRNA and ta-siRNA target RNA levels, similar to those observed using an hypomorphic dcl1 mutation. However, by combining results of transcriptome studies with deep-sequencing data from immuno-precipitated small RNAs, additional, novel endogenous targets of miRNA and ta-siRNA were identified, unraveling an unsuspected complexity in the origin and scope-of-action of these molecules. Other stringent analyses pinpointed misregulation of the miR167 target AUXIN RESPONSE FACTOR 8 (ARF8) as a major cause for the developmental aberrations exhibited by VSR transgenic plants, but also for the phenotypes induced during normal viral infection caused by the HcPro-encoding Turnip mosaic virus (TuMV). Neither RNA silencing, its suppression by VSRs, nor the virulence/accumulation of TuMV was altered by mutations in ARF8. These findings have important implications for our understanding of viral disease symptoms and small RNA-directed regulation of plant growth/development.
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Claims 7
Claim · model-written summary
VSR expression modestly changed known miRNA and ta-siRNA target RNA levels, similarly to a hypomorphic dcl1 mutation.
- Taxon
- Arabidopsis
Arabidopsist0 - Treatment
- VSR expressione0
- Outcome
- miRNA and ta-siRNA target RNA levelse0
- Qualifier
- modeste0
- Comparator
- hypomorphic dcl1 mutatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“VSR expression has comparable, yet modest effects on known miRNA and ta-siRNA target RNA levels, similar to those observed using an hypomorphic dcl1 mutation”
t0“Arabidopsis”
Claim · model-written summary
The transcriptome and small RNA analyses identified new endogenous miRNA and ta-siRNA targets.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- novel endogenous targets of miRNA and ta-siRNAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“additional, novel endogenous targets of miRNA and ta-siRNA were identified”
t0“Arabidopsis”
Claim · model-written summary
ARF8 misregulation was identified as a major cause of developmental abnormalities in VSR transgenic Arabidopsis.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AUXIN RESPONSE FACTOR 8 (ARF8)e0
- Outcome
- developmental aberrationse0
- Qualifier
- misregulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“misregulation of the miR167 target AUXIN RESPONSE FACTOR 8 (ARF8) as a major cause for the developmental aberrations exhibited by VSR transgenic plants”
t0“Arabidopsis”
Claim · model-written summary
ARF8 misregulation was also identified as a major cause of phenotypes induced by Turnip mosaic virus infection.
- Taxon
- ArabidopsisArabidopsist0
- Interactor
- Turnip mosaic virus (TuMV)
Turnip mosaic viruse0pathogen - Outcome
- phenotypes induced during normal viral infectione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but also for the phenotypes induced during normal viral infection caused by the HcPro-encoding Turnip mosaic virus (TuMV)”
t0“Arabidopsis”
Claim · model-written summary
ARF8 mutations did not alter RNA silencing.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- mutations in ARF8e0
- Outcome
- RNA silencinge0
- Direction
- Neithere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither RNA silencing, its suppression by VSRs, nor the virulence/accumulation of TuMV was altered by mutations in ARF8”
t0“Arabidopsis”
Claim · model-written summary
ARF8 mutations did not alter suppression of RNA silencing by VSRs.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- mutations in ARF8e0
- Outcome
- suppression by VSRse0
- Direction
- alterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither RNA silencing, its suppression by VSRs, nor the virulence/accumulation of TuMV was altered by mutations in ARF8”
t0“Arabidopsis”
Claim · model-written summary
ARF8 mutations did not alter Turnip mosaic virus virulence or accumulation.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- mutations in ARF8e0
- Interactor
- TuMVTurnip mosaic viruse0pathogen
- Outcome
- virulence/accumulation of TuMVe0
- Direction
- alterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither RNA silencing, its suppression by VSRs, nor the virulence/accumulation of TuMV was altered by mutations in ARF8”
t0“Arabidopsis”
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See all 8 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.