Abstract
Excised segments of corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles show a strong “spontaneous” increase in growth rate about 4.0 hr after excision. The response can be delayed about 2 hr using a brief (10 min) exposure to IAA during the latent period. An established spontaneous growth response can be suppressed by a 30 to 60 min exposure to auxin and does not reappear until about 2.5 hr after withdrawal of the hormone. During the 3 hr period following withdrawal of exogenous auxin there is a two-fold increase in magnitude and a three-fold decrease in latent period of a growth response to a sub-optimal level of auxin. The data are consistent with the hypothesis that the spontaneous growth response is caused by a time-dependent change in sensitivity of isolated tissue to auxin and/or a change in the endogenous level of auxin. Apical sections of Zea coleoptiles with the tip intact do not grow at the rapid rate one might expect of tissue with an endogenous auxin supply. Instead they grow very poorly and exhibit both a weak spontaneous growth response and a poor response to exogenously supplied auxin. Indirect evidence suggests that this is due to the production of a growth inhibitor by the tip.
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Claims 8
Claim · model-written summary
Excised corn coleoptile segments increased growth rate about four hours after excision.
- Taxon
- corn
Zea mays subsp. mayse0 - Material
- Bear Hybrid WF 9×38e0
- Organ / stage
- coleoptilese0
- Outcome
- growth ratee0
- Direction
- increasee0
- Value
- 4.0 hre0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Excised segments of corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles show a strong “spontaneous” increase in growth rate about 4.0 hr after excision.”
Claim · model-written summary
Brief IAA exposure delayed the spontaneous response about two hours.
- Taxon
- cornZea mays subsp. mayse1
- Organ / stage
- coleoptilese1
- Treatment
- brief (10 min) exposure to IAAe0
- Outcome
- responsee0
- Direction
- delayede0
- Value
- 2 hre0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The response can be delayed about 2 hr using a brief (10 min) exposure to IAA during the latent period.”
e1“corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles”
Claim · model-written summary
Auxin exposure suppressed an established spontaneous growth response until about 2.5 hours after withdrawal.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- 30 to 60 min exposure to auxine0
- Outcome
- spontaneous growth responsee0
- Direction
- suppressede0
- Value
- 2.5 hre0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An established spontaneous growth response can be suppressed by a 30 to 60 min exposure to auxin and does not reappear until about 2.5 hr after withdrawal of the hormone.”
e1“corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles”
Claim · model-written summary
Following auxin withdrawal, response magnitude to suboptimal auxin doubled.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- withdrawal of exogenous auxine0
- Outcome
- magnitudee0
- Direction
- increasee0
- Value
- two-folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the 3 hr period following withdrawal of exogenous auxin there is a two-fold increase in magnitude and a three-fold decrease in latent period of a growth response to a sub-optimal level of auxin.”
e1“corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles”
Claim · model-written summary
Following auxin withdrawal, the response latent period fell threefold.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- withdrawal of exogenous auxine0
- Outcome
- latent periode0
- Direction
- decreasee0
- Value
- three-folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the 3 hr period following withdrawal of exogenous auxin there is a two-fold increase in magnitude and a three-fold decrease in latent period of a growth response to a sub-optimal level of auxin.”
e1“corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles”
Claim · model-written summary
The authors suggest that changing auxin sensitivity or endogenous auxin explains spontaneous growth.
- Taxon
- cornZea mays subsp. mayse1
- Outcome
- spontaneous growth responsee0
- Qualifier
- time-dependent change in sensitivity of isolated tissue to auxin and/or a change in the endogenous level of auxine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the spontaneous growth response is caused by a time-dependent change in sensitivity of isolated tissue to auxin and/or a change in the endogenous level of auxin.”
e1“corn (Zea mays L., Bear Hybrid WF 9×38) coleoptiles”
Claim · model-written summary
Apical Zea coleoptile sections with tips intact grew poorly and showed weak spontaneous and exogenous auxin responses.
- Organ / stage
- Apical sections of Zea coleoptiles with the tip intacte0
- Outcome
- grow very poorly and exhibit both a weak spontaneous growth response and a poor response to exogenously supplied auxine0
- Direction
- poorlye0
ZeaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Apical sections of Zea coleoptiles with the tip intact do not grow at the rapid rate one might expect of tissue with an endogenous auxin supply. Instead they grow very poorly and exhibit both a weak spontaneous growth response and a poor response to exogenously supplied auxin.”
Claim · model-written summary
The authors infer that the tip produces a growth inhibitor.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Indirect evidence suggests that this is due to the production of a growth inhibitor by the tip.”
e1“Apical sections of Zea coleoptiles with the tip intact”
The same questions in other papers
class · growth · Zea mays (maize)Positive and negative results
14 papers in the same direction as this paper · 53 in the opposite direction
- positive
- positive
- positive
64 papers more in this group
See all 68 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.