Abstract
Responses to drought, heat, and combined stress were compared in tobacco (Nicotiana tabacum L.) plants ectopically expressing the cytokinin oxidase/dehydrogenase CKX1 gene of Arabidopsis thaliana L. under the control of either the predominantly root-expressed WRKY6 promoter or the constitutive 35S promoter, and in the wild type. WRKY6:CKX1 plants exhibited high CKX activity in the roots under control conditions. Under stress, the activity of the WRKY6 promoter was down-regulated and the concomitantly reduced cytokinin degradation coincided with raised bioactive cytokinin levels during the early phase of the stress response, which might contribute to enhanced stress tolerance of this genotype. Constitutive expression of CKX1 resulted in an enlarged root system, a stunted, dwarf shoot phenotype, and a low basal level of expression of the dehydration marker gene ERD10B. The high drought tolerance of this genotype was associated with a relatively moderate drop in leaf water potential and a significant decrease in leaf osmotic potential. Basal expression of the proline biosynthetic gene P5CSA was raised. Both wild-type and WRKY6:CKX1 plants responded to heat stress by transient elevation of stomatal conductance, which correlated with an enhanced abscisic acid catabolism. 35S:CKX1 transgenic plants exhibited a small and delayed stomatal response. Nevertheless, they maintained a lower leaf temperature than the other genotypes. Heat shock applied to drought-stressed plants exaggerated the negative stress effects, probably due to the additional water loss caused by a transient stimulation of transpiration. The results indicate that modulation of cytokinin levels may positively affect plant responses to abiotic stress through a variety of physiological mechanisms.
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Claims 17
Claim · model-written summary
WRKY6:CKX1 roots had high CKX activity under control conditions.
- Taxon
- tobacco
Nicotiana tabacumt0 - Material
- WRKY6:CKX1e0
- Organ / stage
- rootse0
- Gene
- CKXe0
- Outcome
- high CKX activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WRKY6:CKX1 plants exhibited high CKX activity in the roots under control conditions.”
t0“tobacco plants”
Claim · model-written summary
Stress down-regulated WRKY6 promoter activity.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- stresse0
- Gene
- WRKY6e0
- Outcome
- activity of the WRKY6 promotere0
- Direction
- down-regulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under stress, the activity of the WRKY6 promoter was down-regulated”
t0“tobacco plants”
Claim · model-written summary
Under stress, cytokinin degradation was reduced as WRKY6 promoter activity fell.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- WRKY6e0
- Outcome
- cytokinin degradatione0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activity of the WRKY6 promoter was down-regulated and the concomitantly reduced cytokinin degradation”
t0“tobacco plants”
Claim · model-written summary
Reduced cytokinin degradation coincided with higher bioactive cytokinin levels early in stress response.
- Taxon
- tobaccoNicotiana tabacumt0
- Compound
- cytokinine0
- Outcome
- bioactive cytokinin levelse0
- Direction
- raisede0
- Qualifier
- early phase of the stress responsee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the concomitantly reduced cytokinin degradation coincided with raised bioactive cytokinin levels during the early phase of the stress response”
t0“tobacco plants”
Claim · model-written summary
Constitutive CKX1 expression enlarged the root system.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Constitutive expression of CKX1e0
- Gene
- CKX1e0
- Outcome
- root systeme0
- Direction
- enlargede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive expression of CKX1 resulted in an enlarged root system”
t0“tobacco plants”
Claim · model-written summary
Constitutive CKX1 expression produced a stunted shoot phenotype.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Constitutive expression of CKX1e0
- Outcome
- shoot phenotypee0
- Direction
- stuntede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive expression of CKX1 resulted in an enlarged root system, a stunted, dwarf shoot phenotype”
t0“tobacco plants”
Claim · model-written summary
Constitutive CKX1 expression produced low basal ERD10B expression.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Constitutive expression of CKX1e0
- Gene
- ERD10Be0
- Outcome
- basal level of expression of the dehydration marker gene ERD10Be0
- Direction
- lowe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive expression of CKX1 resulted in an enlarged root system, a stunted, dwarf shoot phenotype, and a low basal level of expression of the dehydration marker gene ERD10B.”
t0“tobacco plants”
Claim · model-written summary
The CKX1 genotype had high drought tolerance.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- high drought tolerancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high drought tolerance of this genotype was associated with a relatively moderate drop in leaf water potential and a significant decrease in leaf osmotic potential.”
t0“tobacco plants”
Claim · model-written summary
High drought tolerance was associated with a moderate drop in leaf water potential.
- Taxon
- tobaccoNicotiana tabacumt0
- Organ / stage
- leafe0
- Outcome
- leaf water potentiale0
- Direction
- drope0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high drought tolerance of this genotype was associated with a relatively moderate drop in leaf water potential”
t0“tobacco plants”
Claim · model-written summary
High drought tolerance was associated with a significant decline in leaf osmotic potential.
- Taxon
- tobaccoNicotiana tabacumt0
- Organ / stage
- leafe0
- Outcome
- leaf osmotic potentiale0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high drought tolerance of this genotype was associated with a relatively moderate drop in leaf water potential and a significant decrease in leaf osmotic potential.”
t0“tobacco plants”
Claim · model-written summary
Basal P5CSA expression was raised.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- P5CSAe0
- Outcome
- Basal expression of the proline biosynthetic gene P5CSAe0
- Direction
- raisede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Basal expression of the proline biosynthetic gene P5CSA was raised.”
t0“tobacco plants”
Claim · model-written summary
Heat transiently elevated stomatal conductance in wild-type plants.
- Taxon
- tobaccoNicotiana tabacumt0
- Material
- wild-typee0
- Treatment
- heat stresse0
- Outcome
- stomatal conductancee0
- Direction
- elevatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both wild-type and WRKY6:CKX1 plants responded to heat stress by transient elevation of stomatal conductance”
t0“tobacco plants”
Claim · model-written summary
Heat transiently elevated stomatal conductance in WRKY6:CKX1 plants.
- Taxon
- tobaccoNicotiana tabacumt0
- Material
- WRKY6:CKX1e0
- Treatment
- heat stresse0
- Outcome
- stomatal conductancee0
- Direction
- elevatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both wild-type and WRKY6:CKX1 plants responded to heat stress by transient elevation of stomatal conductance”
t0“tobacco plants”
Claim · model-written summary
Stomatal conductance elevation correlated with enhanced abscisic acid catabolism.
- Taxon
- tobaccoNicotiana tabacumt0
- Compound
- abscisic acide0
- Outcome
- stomatal conductancee0
- Direction
- elevatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transient elevation of stomatal conductance, which correlated with an enhanced abscisic acid catabolism.”
t0“tobacco plants”
Claim · model-written summary
35S:CKX1 plants showed a small and delayed stomatal response.
- Taxon
- tobaccoNicotiana tabacumt0
- Material
- 35S:CKX1e0
- Outcome
- small and delayed stomatal responsee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“35S:CKX1 transgenic plants exhibited a small and delayed stomatal response.”
t0“tobacco plants”
Claim · model-written summary
35S:CKX1 plants maintained lower leaf temperature than the other genotypes.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- leaf temperaturee0
- Direction
- lowere0
- Comparator
- other genotypese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nevertheless, they maintained a lower leaf temperature than the other genotypes.”
t0“tobacco plants”
Claim · model-written summary
Heat shock worsened stress effects in drought-stressed plants.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Heat shocke0
- Outcome
- negative stress effectse0
- Direction
- exaggeratede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Heat shock applied to drought-stressed plants exaggerated the negative stress effects”
t0“tobacco plants”
The same questions in other papers
overexpression · growth · Nicotiana tabacum (tobacco)Positive and negative results
7 papers in the same direction as this paper · 13 in the opposite direction
- negative
- negative
- negative
17 papers more in this group
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.