Abstract
This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 In order to investigate the roles of different cell types, metabolite compartmentation in barley ( Hordeum vulgare L.) leaf tissue was mapped at the single-cell level, using single-cell sampling and analysis (SiCSA) techniques. The partitioning of recently fixed photoassimilate was investigated for the first time at single-cell resolution, using BAMS (biological accelerator mass spectroscopy) for precise measurement of 14C in femtomole quantities. The data obtained by BAMS qualitatively reflect concentrations of sugars in different cell types measured by SiCSA. Calculation of 14C-specific activities showed that the radioactive label saturated the mesophyll and parenchymatous bundle sheath (PBS) pools within the 45-min labelling period. During the photoperiod, sucrose concentration increased to 200 mM in mesophyll cells. The concentration of malate also increased during the photoperiod in mesophyll and PBS cells. Epidermal cells contained very low concentrations of sugar but high concentrations of malate (120–180 mM) and did not show significant diurnal changes. Accumulation of sugars and fructan synthesis could be induced in mesophyll and PBS cells by reduced export of sugars from leaves or, alternatively, when sugars were supplied from excised leaf blade bases immersed in a sucrose solution in the dark. The epidermis accumulated additional malate in step with the accumulation of sugar by the mesophyll/PBS cells during the long-term reduction of export. Immunolocalisation of Rubisco and cytochrome oxidase proteins was used to analyse the distribution of enzymes of photoassimilation and respiration between functionally different cells in mature leaves of barley.
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Claims 9
Claim · model-written summary
BAMS radiolabel patterns qualitatively reflected cell-specific sugar concentrations.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaree1 - Outcome
- data obtained by BAMSe0
- Comparator
- concentrations of sugars in different cell types measured by SiCSAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“The data obtained by BAMS qualitatively reflect concentrations of sugars in different cell types measured by SiCSA.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Radiolabel saturated mesophyll and bundle-sheath pools within 45 minutes.
- Taxon
- barleyHordeum vulgaree1
- Outcome
- radioactive label saturated the mesophyll and parenchymatous bundle sheath (PBS) poolse0
- Value
- 45-mine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the radioactive label saturated the mesophyll and parenchymatous bundle sheath (PBS) pools within the 45-min labelling period”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Mesophyll sucrose rose to 200 mM during the photoperiod.
- Taxon
- barleyHordeum vulgaree1
- Organ / stage
- mesophyll cellse0
- Outcome
- sucrose concentratione0
- Direction
- increasede0
- Value
- 200 mMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the photoperiod, sucrose concentration increased to 200 mM in mesophyll cells.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Malate concentration increased during the photoperiod in mesophyll and bundle-sheath cells.
- Taxon
- barleyHordeum vulgaree1
- Organ / stage
- mesophyll and PBS cellse0
- Outcome
- concentration of malatee0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The concentration of malate also increased during the photoperiod in mesophyll and PBS cells.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Epidermal cells had low sugar and high malate concentrations, with malate at 120–180 mM.
- Taxon
- barleyHordeum vulgaree1
- Organ / stage
- Epidermal cellse0
- Outcome
- concentrations of malatee0
- Value
- 120–180 mMe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Epidermal cells contained very low concentrations of sugar but high concentrations of malate (120–180 mM) and did not show significant diurnal changes.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Epidermal metabolite concentrations lacked significant diurnal change.
- Taxon
- barleyHordeum vulgaree1
- Outcome
- diurnal changese0
- Direction
- did not showe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Epidermal cells contained very low concentrations of sugar but high concentrations of malate (120–180 mM) and did not show significant diurnal changes.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Reduced sugar export induced sugar accumulation and fructan synthesis in mesophyll and bundle-sheath cells.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- reduced export of sugars from leavese0
- Outcome
- Accumulation of sugars and fructan synthesise0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Accumulation of sugars and fructan synthesis could be induced in mesophyll and PBS cells by reduced export of sugars from leaves”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Supply from sucrose-soaked excised leaf bases induced sugar accumulation and fructan synthesis.
- Taxon
- barleyHordeum vulgaree1
- Treatment
- sugars were supplied from excised leaf blade bases immersed in a sucrose solution in the darke0
- Outcome
- Accumulation of sugars and fructan synthesise0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Accumulation of sugars and fructan synthesis could be induced in mesophyll and PBS cells by reduced export of sugars from leaves or, alternatively, when sugars were supplied from excised leaf blade bases immersed in a sucrose solution in the dark.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
Claim · model-written summary
Epidermis accumulated additional malate alongside mesophyll and bundle-sheath sugar accumulation during prolonged reduced export.
- Taxon
- barleyHordeum vulgaree1
- Organ / stage
- epidermise0
- Outcome
- additional malatee0
- Direction
- accumulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The epidermis accumulated additional malate in step with the accumulation of sugar by the mesophyll/PBS cells during the long-term reduction of export.”
e1“barley ( Hordeum vulgare L.) leaf tissue”
The same questions in other papers
sucrose · molecular: metabolites · Hordeum vulgare (barley)Results agree
1 paper in the same direction as this paper
- positive
light · molecular: metabolites · Hordeum vulgare (barley)Positive and negative results
18 papers in the same direction as this paper · 11 in the opposite direction
- no effect
- negative
- negative
26 papers more in this group
See all 30 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.