Abstract
BACKGROUND: RNA-silencing is a conserved gene regulation and surveillance machinery, which in plants, is also used as major defence mechanism against viruses. Various virus-specific dsRNA structures are recognized by the silencing machinery leading to degradation of the viral RNAs or, as in case of begomoviruses, to methylation of their DNA genomes. Viruses produce specific RNA silencing suppressor (RSS) proteins to prevent these host defence mechanisms, and as these interfere with the silencing machinery they also disturb the endogenous silencing reactions. In this paper, we describe how expression of AC2 RSS, derived from African cassava mosaic geminivirus changes transcription profile in tobacco (Nicotiana tabacum) leaves and in flowers. RESULTS: Expression of AC2 RSS in transgenic tobacco plants induced clear phenotypic changes both in leaves and in flowers. Transcriptomes of these plants were strongly altered, with total of 1118 and 251 differentially expressed genes in leaves and flowers, respectively. The three most up-regulated transcript groups were related to stress, cell wall modifications and signalling, whereas the three most down-regulated groups were related to translation, photosynthesis and transcription. It appears that many of the gene expression alterations appeared to be related to enhanced biosynthesis of jasmonate and ethylene, and consequent enhancement of the genes and pathways that are regulated by these hormones, or to the retrograde signalling caused by the reduced photosynthetic activity and sugar metabolism. Comparison of these results to a previous transcriptional profiling of HC-Pro RSS-expressing plants revealed that some of same genes were induced by both RSSs, but their expression levels were typically higher in AC2 than in HC-Pro RSS expressing plants. All in all, a large number of transcript alterations were found to be specific to each of the RSS expressing transgenic plants. CONCLUSIONS: AC2 RSS in transgenic tobacco plants interferes with the silencing machinery. It causes stress and defence reactions for instance via induction of the jasmonate and ethylene biosynthesis, and by consequent gene expression alteration regulated by these hormones. The changed sugar metabolism may cause significant down-regulation of genes encoding ribosomal proteins, thus reducing the general translation level.
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Claims 12
Claim · model-written summary
AC2 expression induced clear leaf and flower phenotypic changes in tobacco.
- Taxon
- tobacco
Nicotiana tabacume0 - Organ / stage
- leavese0
- Treatment
- Expression of AC2 RSSe0
- Gene
- AC2 RSSe0
- Outcome
- clear phenotypic changese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expression of AC2 RSS in transgenic tobacco plants induced clear phenotypic changes both in leaves and in flowers.”
Claim · model-written summary
AC2-expressing tobacco leaves had 1118 differentially expressed genes.
- Taxon
- tobaccoNicotiana tabacumt0
- Organ / stage
- leavese0
- Treatment
- Expression of AC2 RSSe1
- Outcome
- differentially expressed genese0
- Value
- 1118e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transcriptomes of these plants were strongly altered, with total of 1118 and 251 differentially expressed genes in leaves and flowers, respectively.”
t0“transgenic tobacco plants”
e1“Expression of AC2 RSS in transgenic tobacco plants”
Claim · model-written summary
AC2-expressing tobacco flowers had 251 differentially expressed genes.
- Taxon
- tobaccoNicotiana tabacumt0
- Organ / stage
- flowerse0
- Treatment
- Expression of AC2 RSSe1
- Outcome
- differentially expressed genese0
- Value
- 251e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transcriptomes of these plants were strongly altered, with total of 1118 and 251 differentially expressed genes in leaves and flowers, respectively.”
t0“transgenic tobacco plants”
e1“Expression of AC2 RSS in transgenic tobacco plants”
Claim · model-written summary
The most up-regulated tobacco transcript groups related to stress, cell-wall modifications and signalling.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- transcript groupse0
- Direction
- up-regulatede0
- Qualifier
- stress, cell wall modifications and signallinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The three most up-regulated transcript groups were related to stress, cell wall modifications and signalling”
t0“tobacco”
Claim · model-written summary
The most down-regulated tobacco transcript groups related to translation, photosynthesis and transcription.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- groupse0
- Direction
- down-regulatede0
- Qualifier
- translation, photosynthesis and transcriptione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the three most down-regulated groups were related to translation, photosynthesis and transcription”
t0“tobacco”
Claim · model-written summary
Many tobacco expression alterations appeared related to enhanced jasmonate and ethylene biosynthesis and their regulated pathways.
- Taxon
- tobaccoNicotiana tabacumt0
- Compound
- jasmonate and ethylenee0
- Outcome
- gene expression alterationse0
- Qualifier
- enhanced biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It appears that many of the gene expression alterations appeared to be related to enhanced biosynthesis of jasmonate and ethylene, and consequent enhancement of the genes and pathways that are regulated by these hormones”
t0“tobacco”
Claim · model-written summary
Expression alterations also appeared related to retrograde signalling caused by reduced photosynthetic activity and sugar metabolism.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- gene expression alterationse0
- Qualifier
- retrograde signalling caused by the reduced photosynthetic activity and sugar metabolisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“many of the gene expression alterations appeared to be related to enhanced biosynthesis of jasmonate and ethylene, and consequent enhancement of the genes and pathways that are regulated by these hormones, or to the retrograde signalling caused by the reduced photosynthetic activity and sugar metabolism”
t0“tobacco”
Claim · model-written summary
Some tobacco genes were induced by both AC2 and HC-Pro, typically at higher expression levels with AC2.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- AC2e0
- Outcome
- expression levelse0
- Direction
- highere0
- Qualifier
- typicallye0
- Comparator
- HC-Proe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some of same genes were induced by both RSSs, but their expression levels were typically higher in AC2 than in HC-Pro RSS expressing plants”
t0“tobacco”
Claim · model-written summary
Many transcript alterations were specific to each RSS-expressing tobacco plant type.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- transcript alterationse0
- Qualifier
- specific to each of the RSS expressing transgenic plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a large number of transcript alterations were found to be specific to each of the RSS expressing transgenic plants”
t0“tobacco”
Claim · model-written summary
AC2 interfered with tobacco silencing machinery.
- Taxon
- tobaccoNicotiana tabacume0
- Gene
- AC2 RSSe0
- Outcome
- interferes with the silencing machinerye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AC2 RSS in transgenic tobacco plants interferes with the silencing machinery.”
Claim · model-written summary
AC2 caused stress and defence reactions via jasmonate and ethylene biosynthesis and hormone-regulated expression changes.
- Taxon
- tobaccoNicotiana tabacumt0
- Compound
- jasmonate and ethylenee0
- Outcome
- stress and defence reactionse0
- Qualifier
- via induction of the jasmonate and ethylene biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It causes stress and defence reactions for instance via induction of the jasmonate and ethylene biosynthesis, and by consequent gene expression alteration regulated by these hormones.”
t0“tobacco”
Claim · model-written summary
Changed sugar metabolism may significantly down-regulate ribosomal-protein genes and reduce general translation in tobacco.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- ribosomal proteinse0
- Outcome
- down-regulation of genes encoding ribosomal proteinse0
- Qualifier
- changed sugar metabolism may causee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The changed sugar metabolism may cause significant down-regulation of genes encoding ribosomal proteins, thus reducing the general translation level.”
t0“tobacco”