Abstract
The Cucumber mosaic virus (CMV) Y-satellite RNA (Y-Sat) has a small non-protein-coding RNA genome that induces yellowing symptoms in infected Nicotiana tabacum (tobacco). How this RNA pathogen induces such symptoms has been a longstanding question. We show that the yellowing symptoms are a result of small interfering RNA (siRNA)-directed RNA silencing of the chlorophyll biosynthetic gene, CHLI. The CHLI mRNA contains a 22-nucleotide (nt) complementary sequence to the Y-Sat genome, and in Y-Sat-infected plants, CHLI expression is dramatically down-regulated. Small RNA sequencing and 5' RACE analyses confirmed that this 22-nt sequence was targeted for mRNA cleavage by Y-Sat-derived siRNAs. Transformation of tobacco with a RNA interference (RNAi) vector targeting CHLI induced Y-Sat-like symptoms. In addition, the symptoms of Y-Sat infection can be completely prevented by transforming tobacco with a silencing-resistant variant of the CHLI gene. These results suggest that siRNA-directed silencing of CHLI is solely responsible for the Y-Sat-induced symptoms. Furthermore, we demonstrate that two Nicotiana species, which do not develop yellowing symptoms upon Y-Sat infection, contain a single nucleotide polymorphism within the siRNA-targeted CHLI sequence. This suggests that the previously observed species specificity of Y-Sat-induced symptoms is due to natural sequence variation in the CHLI gene, preventing CHLI silencing in species with a mismatch to the Y-Sat siRNA. Taken together, these findings provide the first demonstration of small RNA-mediated viral disease symptom production and offer an explanation of the species specificity of the viral disease.
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Claims 8
Claim · model-written summary
Y-Sat yellowing was attributed to siRNA directed CHLI silencing.
- Taxon
- PlantsViridiplantaet0
- Gene
- CHLIe0
- Outcome
- yellowing symptomse0
Verbatim
e0“yellowing symptoms are a result of small interfering RNA (siRNA)-directed RNA silencing of the chlorophyll biosynthetic gene, CHLI”
t0“Plants”
Claim · model-written summary
CHLI mRNA had a 22 nucleotide complementary sequence to Y-Sat.
- Taxon
- PlantsViridiplantaet0
- Gene
- CHLIe0
- Outcome
- 22-nucleotide (nt) complementary sequence to the Y-Sat genomee0
Verbatim
e0“CHLI mRNA contains a 22-nucleotide (nt) complementary sequence to the Y-Sat genome”
t0“Plants”
Claim · model-written summary
CHLI expression was dramatically downregulated in infected plants.
- Taxon
- PlantsViridiplantaet0
- Gene
- CHLIe0
- Outcome
- CHLI expressione0
- Direction
- down-regulatede0
Verbatim
e0“in Y-Sat-infected plants, CHLI expression is dramatically down-regulated”
t0“Plants”
Claim · model-written summary
Y-Sat siRNAs targeted the sequence for mRNA cleavage.
- Taxon
- PlantsViridiplantaet0
- Outcome
- mRNA cleavagee0
Verbatim
e0“this 22-nt sequence was targeted for mRNA cleavage by Y-Sat-derived siRNAs”
t0“Plants”
Claim · model-written summary
CHLI targeted RNA interference caused Y-Sat like tobacco symptoms.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- Transformation of tobacco with a RNA interference (RNAi) vector targeting CHLIe0
- Gene
- CHLIe0
- Outcome
- Y-Sat-like symptomse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transformation of tobacco with a RNA interference (RNAi) vector targeting CHLI induced Y-Sat-like symptoms”
Claim · model-written summary
Silencing resistant CHLI completely prevented Y-Sat symptoms.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- transforming tobacco with a silencing-resistant variant of the CHLI genee0
- Gene
- CHLIe0
- Outcome
- symptoms of Y-Sat infectione0
- Direction
- preventede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“symptoms of Y-Sat infection can be completely prevented by transforming tobacco with a silencing-resistant variant of the CHLI gene”
Claim · model-written summary
Two symptom free Nicotiana species had a SNP in the targeted CHLI sequence.
NicotianaNot reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two Nicotiana species, which do not develop yellowing symptoms upon Y-Sat infection, contain a single nucleotide polymorphism within the siRNA-targeted CHLI sequence”
Claim · model-written summary
The authors attributed species specificity to CHLI variation that prevents silencing.
- Taxon
- PlantsViridiplantaet0
- Gene
- CHLIe0
- Outcome
- species specificity of Y-Sat-induced symptomse0
Verbatim
e0“species specificity of Y-Sat-induced symptoms is due to natural sequence variation in the CHLI gene, preventing CHLI silencing in species with a mismatch to the Y-Sat siRNA”
t0“Plants”
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