Abstract
Decreased cytokinin (CK) export from roots in drying soil might provide a root-to-shoot signal impacting on shoot physiology. Although several studies show that soil drying decreases the CK concentration of xylem sap collected from the roots, it is not known whether this alters xylem CK concentration ([CK(xyl)]) in the leaves and bulk leaf CK concentration. Tomato (Solanum lycopersicum L.) plants were grown with roots split between two soil columns. During experiments, water was applied to both columns (well-watered; WW) or one (partial rootzone drying; PRD) column. Irrigation of WW plants aimed to replace transpirational losses every day, while PRD plants received half this amount. Xylem sap was collected by pressurizing detached leaves using a Scholander pressure chamber, and zeatin-type CKs were immunoassayed using specific antibodies raised against zeatin riboside after separating their different forms (free zeatin, its riboside, and nucleotide) by thin-layer chromatography. PRD decreased the whole plant transpiration rate by 22% and leaf water potential by 0.08 MPa, and increased xylem abscisic acid (ABA) concentration 2.5-fold. Although PRD caused no detectable change in [CK(xyl)], it decreased the CK concentration of fully expanded leaves by 46%. That [CK(xyl)] was maintained and not increased while transpiration decreased suggests that loading of CK into the xylem was also decreased as the soil dried. That leaf CK concentration did not decline proportionally with CK delivery suggests that other mechanisms such as CK metabolism influence leaf CK status of PRD plants. The causes and consequences of decreased shoot CK status are discussed.
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Claims 7
Claim · model-written summary
Partial rootzone drying decreased whole plant transpiration rate by 22%.
- Taxon
- Tomato
Solanum lycopersicumt0 - Treatment
- PRDe0
- Outcome
- whole plant transpiration ratee0
- Direction
- decreasede0
- Value
- 22%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“PRD decreased the whole plant transpiration rate by 22%”
Claim · model-written summary
Partial rootzone drying decreased leaf water potential by 0.08 MPa.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- PRDe0
- Outcome
- leaf water potentiale0
- Direction
- decreasede0
- Value
- 0.08 MPae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“PRD decreased the whole plant transpiration rate by 22% and leaf water potential by 0.08 MPa”
Claim · model-written summary
Partial rootzone drying increased xylem abscisic acid concentration 2.5-fold.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- PRDe0
- Outcome
- xylem abscisic acid (ABA) concentratione0
- Direction
- increasede0
- Value
- 2.5-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“PRD decreased the whole plant transpiration rate by 22% and leaf water potential by 0.08 MPa, and increased xylem abscisic acid (ABA) concentration 2.5-fold”
Claim · model-written summary
Partial rootzone drying caused no detectable change in xylem cytokinin concentration.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- PRDe0
- Outcome
- [CK(xyl)]e0
- Direction
- no detectable changee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“Although PRD caused no detectable change in [CK(xyl)]”
Claim · model-written summary
Partial rootzone drying decreased cytokinin concentration of fully expanded leaves by 46%.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- PRDe0
- Outcome
- CK concentration of fully expanded leavese0
- Direction
- decreasede0
- Value
- 46%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“Although PRD caused no detectable change in [CK(xyl)], it decreased the CK concentration of fully expanded leaves by 46%”
Claim · model-written summary
The authors infer that cytokinin loading into xylem decreased as soil dried.
- Taxon
- TomatoSolanum lycopersicumt0
- Outcome
- loading of CK into the xyleme0
- Direction
- decreasede0
- Qualifier
- as the soil driede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“loading of CK into the xylem was also decreased as the soil dried”
Claim · model-written summary
The authors infer that mechanisms such as cytokinin metabolism influence leaf cytokinin status under partial rootzone drying.
- Taxon
- TomatoSolanum lycopersicumt0
- Outcome
- leaf CK status of PRD plantse0
- Qualifier
- CK metabolisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“tomato (Solanum lycopersicum L.)”
e0“other mechanisms such as CK metabolism influence leaf CK status of PRD plants”
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