Abstract
Expansins are wall proteins that mediate a type of acid-induced extension in isolated plant cell walls (S. McQueen-Mason, D.M. Durachko, D.J. Cosgrove [1992] Plant Cell 4: 1425-1433). To assess the role of these proteins in the process of cell enlargement in living tissues, we compared the spatial and temporal growth patterns of oat (Avena sativa L.) coleoptiles with four wall properties related to expansin action. These properties were (a) the ability of isolated walls and living segments to extend in acidic buffer, (b) the ability of heat-inactivated walls to extend upon application of expansins, (c) the amount of immunologically detectable expansin in wall protein extracts, and (d) the extractable expansin activity of walls. Growth rate was maximal in the apical half of dark-grown coleoptiles and negligible in the basal region. This growth pattern correlated with properties a and b; in contrast, the amount and activity of extractable expansin (properties c and d) were reduced only in the most basal region. Upon exposure to white light, coleoptiles abruptly ceased elongation at 8 to 10 h after start of irradiation, and this cessation correlated with reductions in properties a to c. The growth cessation at 8 to 10 h also coincided with the loss of growth response to exogenous auxin and fusicoccin in excised coleoptile segments. These results lend correlative support to the hypothesis that expansin action is important for growth responses of living oat coleoptiles (e.g. responses to acidic buffers, auxin, fusicoccin, aging, and light). Our results suggest that changes in the susceptibility of the wall to expansin action, rather than changes in expansin activity, may be a key determinant of the growth patterns in oat coleoptiles.
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Claims 8
Claim · model-written summary
Growth rate peaked in the apical half of dark-grown oat coleoptiles.
- Taxon
- oat
Avena sativat0 - Organ / stage
- coleoptilese0
- Outcome
- Growth ratee0
- Direction
- maximale0
- Setting
- apical halfe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Growth rate was maximal in the apical half of dark-grown coleoptiles and negligible in the basal region.”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
Growth rate was negligible in the basal coleoptile region.
- Taxon
- oatAvena sativat0
- Organ / stage
- coleoptilese0
- Outcome
- Growth ratee0
- Direction
- negligiblee0
- Setting
- basal regione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Growth rate was maximal in the apical half of dark-grown coleoptiles and negligible in the basal region.”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
Growth pattern correlated with acid extension of walls and segments and with expansin-induced extension of heat-inactivated walls.
- Taxon
- oatAvena sativat0
- Organ / stage
- coleoptilest0
- Outcome
- growth patterne0
- Qualifier
- properties a and be0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This growth pattern correlated with properties a and b; in contrast, the amount and activity of extractable expansin (properties c and d) were reduced only in the most basal region.”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
Extractable expansin amount and activity were reduced only in the most basal region.
- Taxon
- oatAvena sativat0
- Organ / stage
- coleoptilest0
- Outcome
- amount and activity of extractable expansine0
- Direction
- reducede0
- Setting
- most basal regione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the amount and activity of extractable expansin (properties c and d) were reduced only in the most basal region”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
White light stopped coleoptile elongation 8 to 10 hours after irradiation began.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Upon exposure to white light, coleoptiles abruptly ceased elongation at 8 to 10 h after start of irradiation”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
Light-associated growth cessation correlated with reductions in wall extension properties and detectable expansin.
- Taxon
- oatAvena sativat0
- Organ / stage
- coleoptilest0
- Outcome
- cessatione0
- Qualifier
- reductions in properties a to ce0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this cessation correlated with reductions in properties a to c”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
Growth cessation coincided with lost responses to exogenous auxin and fusicoccin.
- Taxon
- oatAvena sativat0
- Organ / stage
- coleoptile segmentse0
- Outcome
- growth response to exogenous auxin and fusicoccine0
- Direction
- losse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The growth cessation at 8 to 10 h also coincided with the loss of growth response to exogenous auxin and fusicoccin in excised coleoptile segments.”
t0“oat (Avena sativa L.) coleoptiles”
Claim · model-written summary
Wall susceptibility to expansin action may determine oat coleoptile growth patterns.
- Taxon
- oatAvena sativat0
- Organ / stage
- coleoptilese0
- Outcome
- growth patternse0
- Qualifier
- changes in the susceptibility of the wall to expansin actione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in the susceptibility of the wall to expansin action, rather than changes in expansin activity, may be a key determinant of the growth patterns in oat coleoptiles”
t0“oat (Avena sativa L.) coleoptiles”
The same questions in other papers
light · growth · Avena sativa (oats)Positive and negative results
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