Abstract
The time‐course for adjustments in the rate of extension of wheat ( Triticum aestivum L. cv. Alexandria) roots, and the activity and capacity of respiratory pathways in the root apex, were determined after pruning the shoot to the ligule of the first leaf. Leaf pruning reduced the extension rate of both seminal and lateral roots. The onset of the response occurred within 1 h of pruning for laterals and between 2 and 3 h for seminals. The reduction in rate appears to be the result of a decrease in carbohydrate availability because (1) in seminal roots it was preceded by a decrease in soluble sugar content of the apical part of the growth zone (0–5 mm behind the root apex) and (2) supplying glucose (50 m M ) to the roots of plants defoliated 24 h earlier led to a steady increase in extension rate of both seminal and lateral roots compared to non‐fed controls. Supplying 3‐O‐methyl glucose had no effect. The reduction in extension rate of seminal roots was accompanied (or slightly preceded) by a reduction in respiratory O 2 uptake in the apical part of the growth zone (0–5 mm). Changes in respiratory activity in the basal part of the growth zone (5–10 mm) only occurred several hours later. At the time root extension rate was reduced, the rate of O 2 uptake could be stimulated with FCCP, which indicates that respiration was under the fine control of adenylates. From these results we suggest the following sequence of events occurs after defoliation. Firstly, defoliation reduces the supply of sugars to the root apex, this leads to a reduction in rate of extension through some form of coarse control by carbohydrates on cell division and expansion, which in turn reduces the rate of respiratory O 2 uptake because of a smaller demand for ATP. The results also indicate that there is a rapid (<1.5 h) reduction in respiratory capacity in the root apex after defoliation which occurs before any change in the overall rate of respiration.
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Claims 12
Claim · model-written summary
Leaf pruning reduced the extension rate of wheat seminal and lateral roots
- Taxon
- wheat
Triticum aestivumt0 - Organ / stage
- seminal and lateral rootse1
- Treatment
- Leaf pruninge1
- Outcome
- extension ratee1
- Direction
- reducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“Leaf pruning reduced the extension rate of both seminal and lateral roots”
Claim · model-written summary
Onset of the response to pruning occurred within 1 h in lateral roots
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- lateralse1
- Treatment
- pruninge1
- Outcome
- onset of the responsee1
- Value
- within 1 he1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“The onset of the response occurred within 1 h of pruning for laterals and between 2 and 3 h for seminals”
Claim · model-written summary
Onset of the response to pruning occurred between 2 and 3 h in seminal roots
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- seminalse1
- Treatment
- pruninge1
- Outcome
- onset of the responsee1
- Value
- between 2 and 3 he1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“The onset of the response occurred within 1 h of pruning for laterals and between 2 and 3 h for seminals”
Claim · model-written summary
The reduction in wheat root extension rate is suggested to result from a decrease in carbohydrate availability
- Taxon
- wheatTriticum aestivumt0
- Outcome
- reduction in ratee1
- Qualifier
- a decrease in carbohydrate availabilitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“The reduction in rate appears to be the result of a decrease in carbohydrate availability”
Claim · model-written summary
In seminal roots, the reduction in extension rate was preceded by a decrease in soluble sugar content of the apical growth zone
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- apical part of the growth zone (0–5 mm behind the root apex)e1
- Outcome
- soluble sugar contente1
- Direction
- decreasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“in seminal roots it was preceded by a decrease in soluble sugar content of the apical part of the growth zone (0–5 mm behind the root apex)”
Claim · model-written summary
Supplying glucose to defoliated wheat roots led to a steady increase in extension rate compared with non-fed controls
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- seminal and lateral rootse1
- Treatment
- supplying glucose (50 m M )e1
- Outcome
- extension ratee1
- Direction
- increasee1
- Comparator
- non‐fed controlse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“supplying glucose (50 m M ) to the roots of plants defoliated 24 h earlier led to a steady increase in extension rate of both seminal and lateral roots compared to non‐fed controls”
Claim · model-written summary
Supplying 3-O-methyl glucose had no effect on wheat root extension
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Supplying 3‐O‐methyl glucosee1
- Outcome
- effecte1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“Supplying 3‐O‐methyl glucose had no effect”
Claim · model-written summary
The reduction in extension rate of seminal roots was accompanied or slightly preceded by a reduction in respiratory O2 uptake in the apical growth zone
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- apical part of the growth zone (0–5 mm)e1
- Outcome
- respiratory O 2 uptakee1
- Direction
- reductione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“The reduction in extension rate of seminal roots was accompanied (or slightly preceded) by a reduction in respiratory O 2 uptake in the apical part of the growth zone (0–5 mm)”
Claim · model-written summary
Changes in respiratory activity in the basal growth zone only occurred several hours after extension rate was reduced
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- basal part of the growth zone (5–10 mm)e1
- Outcome
- respiratory activitye1
- Qualifier
- only occurred several hours latere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“Changes in respiratory activity in the basal part of the growth zone (5–10 mm) only occurred several hours later”
Claim · model-written summary
At the time extension rate was reduced, the rate of O2 uptake of wheat roots could be stimulated with FCCP
- Taxon
- wheatTriticum aestivumt0
- Treatment
- FCCPe1
- Outcome
- rate of O 2 uptakee1
- Direction
- stimulatede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“At the time root extension rate was reduced, the rate of O 2 uptake could be stimulated with FCCP, which indicates that respiration was under the fine control of adenylates”
Claim · model-written summary
Respiration in wheat roots is suggested to be under the fine control of adenylates
- Taxon
- wheatTriticum aestivumt0
- Outcome
- respiratione1
- Qualifier
- the fine control of adenylatese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“At the time root extension rate was reduced, the rate of O 2 uptake could be stimulated with FCCP, which indicates that respiration was under the fine control of adenylates”
Claim · model-written summary
Defoliation caused a rapid reduction in respiratory capacity in the root apex before any change in overall respiration
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- root apexe1
- Treatment
- defoliatione1
- Outcome
- respiratory capacitye1
- Direction
- reductione1
- Value
- <1.5 he1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat roots”
e1“there is a rapid (<1.5 h) reduction in respiratory capacity in the root apex after defoliation which occurs before any change in the overall rate of respiration”