Abstract
In many species translocation of sucrose from the mesophyll to the phloem is carrier mediated. A sucrose/H+-symporter cDNA, NtSUT1, was isolated from tobacco (Nicotiana tabacum) and shown to be highly expressed in mature leaves and at low levels in other tissues, including floral organs. To study the in vivo function of NtSUT1, tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter. Upon maturation, leaves of transformants expressing reduced amounts of SUT1 mRNA curled downward, and strongly affected plants developed chloroses and necroses that led to death. The leaves exhibited impaired ability to export recently fixed 14CO2 and were unable to export transient starch during extended periods of darkness. As a consequence, soluble carbohydrates accumulated and photosynthesis was reduced. Autoradiographs of leaves show a heterogenous pattern of CO2 fixation even after a 24-h chase. The 14C pattern does not change with time, suggesting that movement of photosynthate between mesophyll cells may also be impaired. The affected lines show a reduction in the development of the root system and delayed or impaired flowering. Taken together, the effects observed in a seed plant (tobacco) demonstrate the importance of SUT1 for sucrose loading into the phloem via an apoplastic route and possibly for intermesophyll transport as well.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 12
Claim · model-written summary
NtSUT1 is highly expressed in mature tobacco leaves and at low levels in other tissues.
- Taxon
- tobacco
Nicotiana tabacume1 - Organ / stage
- mature leavese1
- Gene
- NtSUT1e1
- Outcome
- highly expressede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A sucrose/H+-symporter cDNA, NtSUT1, was isolated from tobacco (Nicotiana tabacum) and shown to be highly expressed in mature leaves and at low levels in other tissues, including floral organs”
Claim · model-written summary
Tobacco transformants with a SUT1 antisense construct show leaves curled downward and negative phenotypes.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Gene
- SUT1e3
- Outcome
- curled downwarde3
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e3“Upon maturation, leaves of transformants expressing reduced amounts of SUT1 mRNA curled downward, and strongly affected plants developed chloroses and necroses that led to death”
Claim · model-written summary
Strongly affected tobacco antisense plants develop chloroses and necroses that lead to death.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- chloroses and necrosese3
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e3“Upon maturation, leaves of transformants expressing reduced amounts of SUT1 mRNA curled downward, and strongly affected plants developed chloroses and necroses that led to death”
Claim · model-written summary
Antisense tobacco leaves have impaired ability to export recently fixed 14CO2.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- ability to export recently fixed 14CO2e4
- Direction
- impairede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e4“The leaves exhibited impaired ability to export recently fixed 14CO2 and were unable to export transient starch during extended periods of darkness”
Claim · model-written summary
Antisense tobacco leaves are unable to export transient starch during extended darkness.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- transient starche4
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e4“The leaves exhibited impaired ability to export recently fixed 14CO2 and were unable to export transient starch during extended periods of darkness”
Claim · model-written summary
Soluble carbohydrates accumulate in antisense tobacco leaves.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- soluble carbohydratese5
- Direction
- accumulatede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e5“As a consequence, soluble carbohydrates accumulated and photosynthesis was reduced”
Claim · model-written summary
Photosynthesis is reduced in antisense tobacco plants.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- photosynthesise5
- Direction
- reducede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e5“As a consequence, soluble carbohydrates accumulated and photosynthesis was reduced”
Claim · model-written summary
Antisense tobacco leaves show a heterogeneous pattern of CO2 fixation.
- Taxon
- tobaccoNicotiana tabacume1
- Organ / stage
- leavese6
- Outcome
- heterogenous pattern of CO2 fixatione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A sucrose/H+-symporter cDNA, NtSUT1, was isolated from tobacco (Nicotiana tabacum) and shown to be highly expressed in mature leaves and at low levels in other tissues, including floral organs”
e6“Autoradiographs of leaves show a heterogenous pattern of CO2 fixation even after a 24-h chase”
Claim · model-written summary
Movement of photosynthate between mesophyll cells may also be impaired in tobacco.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- movement of photosynthate between mesophyll cellse7
- Qualifier
- may also be impairede7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“A sucrose/H+-symporter cDNA, NtSUT1, was isolated from tobacco (Nicotiana tabacum) and shown to be highly expressed in mature leaves and at low levels in other tissues, including floral organs”
e7“The 14C pattern does not change with time, suggesting that movement of photosynthate between mesophyll cells may also be impaired”
Claim · model-written summary
Antisense tobacco lines show reduced root system development.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- development of the root systeme3
- Direction
- reductione3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e3“The affected lines show a reduction in the development of the root system and delayed or impaired flowering”
Claim · model-written summary
Antisense tobacco lines show delayed flowering.
- Taxon
- tobaccoNicotiana tabacume2
- Treatment
- SUT1 antisense constructe2
- Outcome
- floweringe3
- Direction
- delayede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“tobacco plants were transformed with a SUT1 antisense construct under control of the cauliflower mosaic virus 35S promoter”
e3“The affected lines show a reduction in the development of the root system and delayed or impaired flowering”
Claim · model-written summary
SUT1 is important for sucrose loading into the phloem via an apoplastic route and possibly for intermesophyll transport.
- Taxon
- tobaccoNicotiana tabacume3
- Gene
- SUT1e3
- Outcome
- sucrose loading into the phloem via an apoplastic routee3
- Qualifier
- possibly for intermesophyll transport as welle3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Taken together, the effects observed in a seed plant (tobacco) demonstrate the importance of SUT1 for sucrose loading into the phloem via an apoplastic route and possibly for intermesophyll transport as well”
The same questions in other papers
loss of function · phenology · Nicotiana tabacum (tobacco)Positive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- negative
1 paper more in this group
See all 5 papers →loss of function · growth · Nicotiana tabacum (tobacco)Positive and negative results
33 papers in the same direction as this paper · 5 in the opposite direction
- positive
- positive
- positive
35 papers more in this group
See all 39 papers →loss of function · quality: sugar starch · Nicotiana tabacum (tobacco)Results agree
2 papers in the same direction as this paper
- no effect
- negative
loss of function · physiology: photosynthesis · Nicotiana tabacum (tobacco)Results agree
9 papers in the same direction as this paper
- negative
- negative
- negative
6 papers more in this group
See all 10 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.