Abstract
Cauliflower mosaic virus (CaMV) open reading frame (ORF) VI product (P6) has been shown to be the major constituent of viral inclusion body, to function as a post-transcriptional transactivator, and to be essential for infectivity on whole plants. Although these findings suggest that P6 has an important role in viral multiplication, it is unknown whether P6 is required for viral multiplication in a single cell. To address this question, we transfected turnip protoplasts with an ORF VI frame-shift (4 bp deletion) mutant (pCaFS6) of an infectious CaMV DNA clone (pCa122). The mutant was uninfectious. Co-transfection of plasmids expressing P6 complemented the mutant. Overexpression of P6 elevated the infection rate in co-transfection experiments with either pCa122 or pCaFS6. This would have been achieved by elevating the level of pregenomic 35S RNA, a putative polycistronic mRNA for ORFs I, II, III, IV and V, and by enhancing the accumulation of these five viral gene products. When CaMV ORFs I, II, III, IV and V were expressed from monocistronic constructs in which each of the ORFs was placed just downstream of the 35S promoter, the accumulation of ORF III, IV and V products depended on the co-expression of P6. The accumulation of ORF I and II products was not detected, even in the presence of P6. These results suggest that P6 is involved in the stabilization of other viral gene products as well as in the activation of viral gene expression, and thus, is a prerequisite for CaMV multiplication.
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Claims 6
Claim · model-written summary
The ORF VI frame-shift mutant was uninfectious in turnip protoplasts.
- Taxon
- turnip
.jpg?width=60)
Brassica rapa subsp. rapae0 - Treatment
- ORF VI frame-shift (4 bp deletion) mutant (pCaFS6)e0
- Interactor
- CaMV
Cauliflower mosaic viruse0pathogen - Gene
- ORF VIe0
- Outcome
- uninfectiouse0
- Comparator
- pCa122e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“transfected turnip protoplasts with an ORF VI frame-shift (4 bp deletion) mutant (pCaFS6) of an infectious CaMV DNA clone (pCa122). The mutant was uninfectious”
Claim · model-written summary
Co-transfected P6-expressing plasmids complemented the mutant in turnip protoplasts.
- Taxon
- turnipBrassica rapa subsp. rapae0
- Treatment
- Co-transfection of plasmids expressing P6e0
- Interactor
- CaMVCauliflower mosaic viruse0pathogen
- Gene
- P6e0
- Outcome
- complemented the mutante0
- Comparator
- mutante0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transfected turnip protoplasts with an ORF VI frame-shift (4 bp deletion) mutant (pCaFS6) of an infectious CaMV DNA clone (pCa122). The mutant was uninfectious. Co-transfection of plasmids expressing P6 complemented the mutant”
Claim · model-written summary
P6 overexpression elevated infection rate with the infectious clone in turnip protoplasts.
- Taxon
- turnipBrassica rapa subsp. rapae0
- Treatment
- Overexpression of P6e1
- Interactor
- CaMVCauliflower mosaic viruse0pathogen
- Gene
- P6e1
- Outcome
- infection ratee1
- Direction
- elevatede1
- Comparator
- pCa122e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transfected turnip protoplasts with an ORF VI frame-shift (4 bp deletion) mutant (pCaFS6) of an infectious CaMV DNA clone (pCa122)”
e1“Overexpression of P6 elevated the infection rate in co-transfection experiments with either pCa122 or pCaFS6”
Claim · model-written summary
P6 overexpression elevated infection rate with the frame-shift mutant in turnip protoplasts.
- Taxon
- turnipBrassica rapa subsp. rapae0
- Treatment
- Overexpression of P6e1
- Interactor
- CaMVCauliflower mosaic viruse0pathogen
- Gene
- P6e1
- Outcome
- infection ratee1
- Direction
- elevatede1
- Comparator
- pCaFS6e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transfected turnip protoplasts with an ORF VI frame-shift (4 bp deletion) mutant (pCaFS6) of an infectious CaMV DNA clone (pCa122)”
e1“Overexpression of P6 elevated the infection rate in co-transfection experiments with either pCa122 or pCaFS6”
Claim · model-written summary
P6 co-expression was required for accumulation of viral ORF III, IV and V products.
- Taxon
- turnipBrassica rapa subsp. rapae0
- Interactor
- CaMVCauliflower mosaic viruse2pathogen
- Gene
- P6e1
- Outcome
- accumulation of ORF III, IV and V productse1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“turnip protoplasts”
e1“the accumulation of ORF III, IV and V products depended on the co-expression of P6”
e2“CaMV ORFs I, II, III, IV and V were expressed from monocistronic constructs”
Claim · model-written summary
Viral ORF I and II products were not detected even with P6.
- Taxon
- turnipBrassica rapa subsp. rapae0
- Interactor
- CaMVCauliflower mosaic viruse2pathogen
- Gene
- P6e1
- Outcome
- accumulation of ORF I and II products was not detectede1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“turnip protoplasts”
e1“The accumulation of ORF I and II products was not detected, even in the presence of P6”
e2“CaMV ORFs I, II, III, IV and V were expressed from monocistronic constructs”