Abstract
Effects of indoleacetic acid (IAA) and of turgor changes on the apparent molecular mass (Mr) distributions of cell wall matrix polysaccharides from etiolated pea (Pisum sativum L.) epicotyl segments were determined by gel filtration chromatography. IAA causes a two- to threefold decline in the peak Mr of xyloglucan, relative to minus-auxin controls, to occur within 0.5 hour. IAA causes an even larger decrease in the peak Mr concurrently biosynthesized xyloglucan, as determined by [3H]fucose labeling, but this effect begins only after 1 hour. In contrast, IAA does not appreciably affect the Mr distributions of pectic polyuronides or hemicellulosic arabinose/galactose polysaccharides within 1.5 hours. However, after epicotyl segments are cut, their peak polyuronide Mr increases and later decreases, possibly as part of a wound response. Xyloglucan also undergoes IAA-independent changes in its Mr distribution after cutting segments. In addition, the peak Mr of newly deposited xyloglucan increases from about 9 kilodaltons shortly after deposition to about 30 kilodaltons within 0.5 hour. This may represent a process of integration into the cell wall. A step increase in turgor causes the peak Mr Of previously deposited xyloglucan (but not of the other major polymers) to increase about 10-fold within 0.5 hour, returning to its initial value by 1.5 hours. This upshift may comprise a feedback mechanism that decreases wall extensibility when the rate of wall extension suddenly increases. IAA-induced reduction of xyloglucan Mr might cause wall loosening that leads to cell enlargement, as has been suggested previously, but the lack of a simple relation between xyloglucan Mr and elongation rate indicates that loosening must also involve other wall factors, one of which might be the deposition of new xyloglucan of much smaller size. Although the Mr shifts in polyuronides may represent changes in noncovalent association, and for xyloglucan this cannot be completely excluded, xyloglucan seems to participate in a dynamic process that can both decrease and increase its chain length, possible mechanisms for which are suggested.
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Claims 9
Claim · model-written summary
IAA caused a two- to threefold decline in the peak molecular mass of xyloglucan relative to minus-auxin controls within 0.5 hour.
- Taxon
- Pea
Lathyrus oleraceust0 - Treatment
- IAAe0
- Outcome
- peak Mr of xyloglucane0
- Direction
- declinee0
- Value
- two- to threefolde0
- Qualifier
- within 0.5 houre0
- Comparator
- minus-auxin controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“IAA causes a two- to threefold decline in the peak Mr of xyloglucan, relative to minus-auxin controls, to occur within 0.5 hour”
Claim · model-written summary
IAA caused an even larger decrease in the peak molecular mass of concurrently biosynthesized xyloglucan, beginning only after 1 hour.
- Taxon
- PeaLathyrus oleraceust0
- Treatment
- IAAe0
- Outcome
- peak Mr concurrently biosynthesized xyloglucane0
- Direction
- larger decreasee0
- Qualifier
- begins only after 1 houre0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“IAA causes an even larger decrease in the peak Mr concurrently biosynthesized xyloglucan, as determined by [3H]fucose labeling, but this effect begins only after 1 hour”
Claim · model-written summary
IAA did not appreciably affect the molecular mass distributions of pectic polyuronides or hemicellulosic arabinose/galactose polysaccharides within 1.5 hours.
- Taxon
- PeaLathyrus oleraceust0
- Treatment
- IAAe0
- Outcome
- Mr distributions of pectic polyuronides or hemicellulosic arabinose/galactose polysaccharidese0
- Direction
- no_changeinferrede0
- Qualifier
- within 1.5 hourse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“IAA does not appreciably affect the Mr distributions of pectic polyuronides or hemicellulosic arabinose/galactose polysaccharides within 1.5 hours”
Claim · model-written summary
After epicotyl segments were cut, the peak polyuronide molecular mass increased and later decreased.
- Taxon
- PeaLathyrus oleraceust0
- Treatment
- epicotyl segments are cute0
- Outcome
- peak polyuronide Mre0
- Direction
- increases and later decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“after epicotyl segments are cut, their peak polyuronide Mr increases and later decreases”
Claim · model-written summary
Xyloglucan underwent IAA-independent changes in its molecular mass distribution after segments were cut.
- Taxon
- PeaLathyrus oleraceust0
- Treatment
- cutting segmentse0
- Outcome
- Mr distributione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“Xyloglucan also undergoes IAA-independent changes in its Mr distribution after cutting segments”
Claim · model-written summary
The peak molecular mass of newly deposited xyloglucan increased from about 9 to about 30 kilodaltons within 0.5 hour of deposition.
- Taxon
- PeaLathyrus oleraceust0
- Outcome
- peak Mr of newly deposited xyloglucane0
- Direction
- increasese0
- Value
- from about 9 kilodaltons shortly after deposition to about 30 kilodaltonse0
- Qualifier
- within 0.5 houre0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“the peak Mr of newly deposited xyloglucan increases from about 9 kilodaltons shortly after deposition to about 30 kilodaltons within 0.5 hour”
Claim · model-written summary
A step increase in turgor raised the peak molecular mass of previously deposited xyloglucan about 10-fold within 0.5 hour, but not that of the other major polymers.
- Taxon
- PeaLathyrus oleraceust0
- Treatment
- A step increase in turgore0
- Outcome
- peak Mr Of previously deposited xyloglucane0
- Direction
- increasee0
- Value
- about 10-folde0
- Qualifier
- within 0.5 houre0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“A step increase in turgor causes the peak Mr Of previously deposited xyloglucan (but not of the other major polymers) to increase about 10-fold within 0.5 hour”
Claim · model-written summary
The turgor-induced upshift in xyloglucan molecular mass may be a feedback mechanism that decreases wall extensibility when wall extension rate suddenly increases.
- Taxon
- PeaLathyrus oleraceust0
- Outcome
- wall extensibilitye0
- Qualifier
- feedback mechanisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“This upshift may comprise a feedback mechanism that decreases wall extensibility when the rate of wall extension suddenly increases”
Claim · model-written summary
The lack of a simple relation between xyloglucan molecular mass and elongation rate indicates that wall loosening must also involve other wall factors.
- Taxon
- PeaLathyrus oleraceust0
- Outcome
- elongation ratee0
- Qualifier
- loosening must also involve other wall factorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Pea”
e0“the lack of a simple relation between xyloglucan Mr and elongation rate indicates that loosening must also involve other wall factors”
The same questions in other papers
indole-3-acetic acid · molecular: metabolites · Lathyrus oleraceus (pea)Positive and negative results
6 papers in the same direction as this paper · 12 in the opposite direction
- positive
- positive
- positive
15 papers more in this group
See all 19 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.