Abstract
Tomato Golden Mosaic Virus (TGMV) is a DNA virus that replicates and transcribes its genome in plant nuclei. TGMV was modified to serve as a gene silencing vector in Nicotiana benthamiana by insertion of small fragments (120 — 160 bp) downstream of the viral BR1 gene. Inoculation by microprojectile bombardment resulted in local silencing after 5-7 days and persistent systemic silencing. Previously, TGMV vectors were used to silence genes needed for chlorophyll biosynthesis. The purpose of my research was to determine if TGMV vectors could be used to provide information about genes essential for DNA replication and plant development. I tested TGMV vectors containing 120 — 150 bp inserts from genes encoding the N. benthamiana proliferating cell nuclear antigen (PCNA) and N. tabacum retinoblastoma-related protein (pRBR). PCNA is essential for DNA replication and pRBR is needed for cell cycle control. TGMV-mediated silencing of PCNA resulted in an irreversible cessation of primary growth. Leaves were clustered, showed truncated expansion, and fused with the stem at their base. Meristematic-like structures that were elongate, lacked leaf primordia, and contained files of cells that did not expand were found, but only in a small proportion of silenced plants. Immunolocalization demonstrated that PCNA expression was silenced throughout these structures. These experiments provided the first evidence that TGMVinduced silencing could down-regulate expression in meristems, and suggested that proper PCNA expression could be required for cell expansion as well as primary growth. TGMV-mediated gene silencing of RBR resulted in delayed programmed cell death in mature tissues, as demonstrated by Trypan blue staining. Wild type TGMV infectionsproduced severe symptoms but did not result in cell death. Systemically silenced leaves of TGMV::RBR inoculated plants had developmental defects that were distinct from symptoms. Flower corollas were abnormally curled and some flowers were infertile. A low but reproducible proportion of progeny derived from the seed of curled flowers also had abnormal leaf growth suggestive of an epigenetic modification. The onset of cell death in mature tissues of pRBR-silenced plants and the developmental defects in new growth suggests that pRBR may have distinct roles in dividing cells and differentiated tissues.
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Claims 15
Claim · model-written summary
Modified TGMV produced local silencing after 5-7 days and persistent systemic silencing.
- Taxon
- Nicotiana benthamiana
Nicotiana benthamianat0 - Treatment
- Inoculation by microprojectile bombardmente0
- Outcome
- local silencinge0
- Value
- 5-7 dayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation by microprojectile bombardment resulted in local silencing after 5-7 days and persistent systemic silencing.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
TGMV silencing of PCNA irreversibly stopped primary growth.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Treatment
- TGMV-mediated silencing of PCNAe0
- Gene
- PCNAe0
- Outcome
- primary growthe0
- Direction
- cessatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“TGMV-mediated silencing of PCNA resulted in an irreversible cessation of primary growth.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
PCNA-silenced leaves clustered, had truncated expansion and fused to stems.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Organ / stage
- Leavese0
- Outcome
- clustered, showed truncated expansion, and fused with the stem at their basee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves were clustered, showed truncated expansion, and fused with the stem at their base.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
A small proportion of silenced plants formed elongate meristematic-like structures lacking leaf primordia and containing nonexpanding cells.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Outcome
- Meristematic-like structures that were elongate, lacked leaf primordia, and contained files of cells that did not expande0
- Qualifier
- only in a small proportion of silenced plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Meristematic-like structures that were elongate, lacked leaf primordia, and contained files of cells that did not expand were found, but only in a small proportion of silenced plants.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
PCNA expression was silenced throughout those structures.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Gene
- PCNAe0
- Outcome
- PCNA expressione0
- Direction
- silencede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PCNA expression was silenced throughout these structures.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
TGMV silencing can down-regulate expression in meristems.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Outcome
- expression in meristemse0
- Direction
- down-regulatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“TGMVinduced silencing could down-regulate expression in meristems”
t0“in Nicotiana benthamiana”
Claim · model-written summary
Proper PCNA expression may be needed for cell expansion and primary growth.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Gene
- PCNAe0
- Outcome
- cell expansion as well as primary growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“proper PCNA expression could be required for cell expansion as well as primary growth.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
TGMV silencing of RBR delayed programmed cell death in mature tissues.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Treatment
- TGMV-mediated gene silencing of RBRe0
- Gene
- RBRe0
- Outcome
- programmed cell deathe0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“TGMV-mediated gene silencing of RBR resulted in delayed programmed cell death in mature tissues”
t0“in Nicotiana benthamiana”
Claim · model-written summary
Wild-type TGMV caused severe symptoms without cell death.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Interactor
- TGMVTomato golden mosaic viruse0pathogen
- Outcome
- severe symptomse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wild type TGMV infectionsproduced severe symptoms but did not result in cell death.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
Systemically silenced TGMV::RBR leaves had developmental defects distinct from viral symptoms.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Organ / stage
- leavese0
- Outcome
- developmental defectse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Systemically silenced leaves of TGMV::RBR inoculated plants had developmental defects that were distinct from symptoms.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
Some flowers had abnormally curled corollas.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Organ / stage
- Flower corollase0
- Outcome
- abnormally curlede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Flower corollas were abnormally curled and some flowers were infertile.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
Some flowers were infertile.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Organ / stage
- flowerse0
- Outcome
- infertilee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some flowers were infertile”
t0“in Nicotiana benthamiana”
Claim · model-written summary
A small reproducible proportion of offspring from curled flowers had abnormal leaf growth.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Outcome
- abnormal leaf growthe0
- Qualifier
- A low but reproducible proportione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A low but reproducible proportion of progeny derived from the seed of curled flowers also had abnormal leaf growth”
t0“in Nicotiana benthamiana”
Claim · model-written summary
The offspring phenotype suggests an epigenetic modification.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Outcome
- abnormal leaf growthe0
- Qualifier
- epigenetic modificatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“abnormal leaf growth suggestive of an epigenetic modification.”
t0“in Nicotiana benthamiana”
Claim · model-written summary
pRBR may have distinct roles in dividing and differentiated cells.
- Taxon
- Nicotiana benthamianaNicotiana benthamianat0
- Gene
- pRBRe0
- Outcome
- distinct roles in dividing cells and differentiated tissuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pRBR may have distinct roles in dividing cells and differentiated tissues.”
t0“in Nicotiana benthamiana”
The same questions in other papers
loss of function · growth · Nicotiana benthamianaPositive and negative results
16 papers in the same direction as this paper · 4 in the opposite direction
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See all 21 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.