Abstract
Bromoviral templates for plus-strand RNA synthesis are rich in A or U nucleotides in comparison to templates for minus-strand RNA synthesis. Previous studies demonstrated that plus-strand RNA synthesis by the brome mosaic virus (BMV) RNA replicase is more efficient if the template contains an A/U-rich template sequence near the initiation site (K. Sivakumaran and C. C. Kao, J. Virol. 73:6415-6423, 1999). These observations led us to examine the effects of nucleotide changes near the template's initiation site on the accumulation of BMV RNA3 genomic minus-strand, genomic plus-strand, and subgenomic RNAs in barley protoplasts transfected with wild-type and mutant BMV transcripts. Mutations in the template for minus-strand synthesis had only modest effects on BMV replication in barley protoplasts. Mutants with changes to the +3, +5, and +7 template nucleotides accumulated minus-strand RNA at levels similar to the the wild-type level. However, mutations at positions adjacent to the initiation cytidylate in the templates for genomic and subgenomic plus-strand RNA synthesis significantly decreased RNA accumulation. For example, changes at the third template nucleotide for plus-strand RNA3 synthesis resulted in RNA accumulation at between 18 and 24% of the wild-type level, and mutations in the third template nucleotide for subgenomic RNA4 resulted in accumulations at between 7 and 14% of the wild-type level. The effects of the mutations generally decreased as the mutations occurred further from the initiation nucleotide. These findings demonstrate that there are different requirements of the template sequence near the initiation nucleotide for BMV RNA accumulation in plant cells.
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Claims 6
Claim · model-written summary
Minus-strand template mutations had only modest effects on viral replication.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaree0 - Treatment
- Mutations in the template for minus-strand synthesise0
- Interactor
- BMV
Brome mosaic viruse0pathogen - Outcome
- BMV replicatione0
- Direction
- modest effectse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Mutations in the template for minus-strand synthesis had only modest effects on BMV replication in barley protoplasts”
Claim · model-written summary
Changes at +3, +5 and +7 yielded minus-strand RNA levels similar to wild type.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- changes to the +3, +5, and +7 template nucleotidese0
- Interactor
- Brome Mosaic VirusBrome mosaic virust0pathogen
- Outcome
- minus-strand RNAe0
- Direction
- similare0
- Comparator
- wild-type levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mutants with changes to the +3, +5, and +7 template nucleotides accumulated minus-strand RNA at levels similar to the the wild-type level”
t0“Brome Mosaic Virus RNA Accumulation in Plant Protoplasts”
e1“BMV replication in barley protoplasts”
Claim · model-written summary
Mutations next to the initiation cytidylate significantly decreased plus-strand RNA accumulation.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- mutations at positions adjacent to the initiation cytidylatee0
- Interactor
- Brome Mosaic VirusBrome mosaic virust0pathogen
- Outcome
- RNA accumulatione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mutations at positions adjacent to the initiation cytidylate in the templates for genomic and subgenomic plus-strand RNA synthesis significantly decreased RNA accumulation”
t0“Brome Mosaic Virus RNA Accumulation in Plant Protoplasts”
e1“BMV replication in barley protoplasts”
Claim · model-written summary
Third-nucleotide RNA3 changes reduced viral RNA accumulation to 18–24% of wild type.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- changes at the third template nucleotide for plus-strand RNA3 synthesise0
- Interactor
- Brome Mosaic VirusBrome mosaic virust0pathogen
- Outcome
- RNA accumulatione0
- Value
- between 18 and 24%e0
- Comparator
- wild-type levele0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes at the third template nucleotide for plus-strand RNA3 synthesis resulted in RNA accumulation at between 18 and 24% of the wild-type level”
t0“Brome Mosaic Virus RNA Accumulation in Plant Protoplasts”
e1“BMV replication in barley protoplasts”
Claim · model-written summary
Third-nucleotide RNA4 changes reduced viral RNA accumulation to 7–14% of wild type.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- mutations in the third template nucleotide for subgenomic RNA4e0
- Interactor
- Brome Mosaic VirusBrome mosaic virust0pathogen
- Outcome
- accumulationse0
- Value
- between 7 and 14%e0
- Comparator
- wild-type levele0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mutations in the third template nucleotide for subgenomic RNA4 resulted in accumulations at between 7 and 14% of the wild-type level”
t0“Brome Mosaic Virus RNA Accumulation in Plant Protoplasts”
e1“BMV replication in barley protoplasts”
Claim · model-written summary
Mutation effects decreased farther from the initiation nucleotide.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- mutationse0
- Outcome
- effects of the mutationse0
- Direction
- decreasede0
- Qualifier
- further from the initiation nucleotidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effects of the mutations generally decreased as the mutations occurred further from the initiation nucleotide”
t0“Brome Mosaic Virus RNA Accumulation in Plant Protoplasts”
e1“BMV replication in barley protoplasts”