Abstract
Control of leaf expansion by auxin is not well understood. Evidence from short‐term exogenous applications and from treatment of excised tissues suggests auxin positively influences growth. Manipulations of endogenous leaf auxin content, however, suggest that long‐term auxin suppresses leaf expansion. This study attempts to clarify the growth effects of auxin on unifoliate (primary) leaves of the common bean ( Phaseolus vulgaris ) by reexamining the response to auxin treatment of both excised leaf strips and attached leaves. Leaf strips, incubated in culture conditions that promoted steady elongation for up to 48 h, treated with 10 μ M α‐naphthalene acetic acid (NAA) responded with an initial surge of elongation growth complete within 10 h, followed by insensitivity. A range of NAA concentrations from 0.1 to 300 μ M induced increased strip elongation after 24 and 48 h. Increased elongation and epinastic curvature of leaf strips was found specific to active auxins. Expanding attached unifoliates treated once with aqueous auxin NAA at 1.0 m M showed both an initial surge in growth lasting 4–6 h followed by growth inhibition sustained at least as long as 24 h post‐treatment. Auxin‐induced inhibition of leaf expansion was associated with smaller epidermal cell area. Together, the results suggest increasing leaf auxin first increases growth and then slows growth through inhibition of cell expansion. Excised leaf strips retain only the initial increased growth response to auxin and not the subsequent growth inhibition, either as a consequence of wounding or as a consequence of isolation from the plant.
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Claims 9
Claim · model-written summary
NAA induced an initial elongation surge in excised leaf strips, ending within 10 h.
- Taxon
- Phaseolus vulgaris
Phaseolus vulgarise0 - Organ / stage
- Leaf stripse2
- Treatment
- 10 μ M α‐naphthalene acetic acide1
- Outcome
- elongation growthe1
- Direction
- surgee1
- Value
- 10 he1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“treated with 10 μ M α‐naphthalene acetic acid (NAA) responded with an initial surge of elongation growth complete within 10 h”
e2“Leaf strips, incubated in culture conditions that promoted steady elongation for up to 48 h”
Claim · model-written summary
Leaf strips became insensitive after the initial growth surge.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Treatment
- 10 μ M α‐naphthalene acetic acide2
- Outcome
- insensitivitye1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“followed by insensitivity”
e2“treated with 10 μ M α‐naphthalene acetic acid (NAA)”
Claim · model-written summary
NAA at 0.1–300 μM increased strip elongation after 24 and 48 h.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Treatment
- NAA concentrations from 0.1 to 300 μ Me1
- Outcome
- strip elongatione1
- Direction
- increasede1
- Qualifier
- after 24 and 48 he1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“A range of NAA concentrations from 0.1 to 300 μ M induced increased strip elongation after 24 and 48 h”
Claim · model-written summary
Increased strip elongation and epinastic curvature were specific to active auxins.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Treatment
- active auxinse1
- Outcome
- elongation and epinastic curvature of leaf stripse1
- Direction
- Increasede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“Increased elongation and epinastic curvature of leaf strips was found specific to active auxins”
Claim · model-written summary
One NAA treatment caused a 4–6 h initial growth surge in attached leaves.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Organ / stage
- Expanding attached unifoliatese1
- Treatment
- aqueous auxin NAA at 1.0 m Me1
- Outcome
- growthe1
- Direction
- surgee1
- Value
- 4–6 he1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“Expanding attached unifoliates treated once with aqueous auxin NAA at 1.0 m M showed both an initial surge in growth lasting 4–6 h”
Claim · model-written summary
The NAA growth surge was followed by inhibition lasting at least 24 h.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Treatment
- aqueous auxin NAA at 1.0 m Me1
- Outcome
- growthe1
- Direction
- inhibitione1
- Qualifier
- at least as long as 24 h post‐treatmente1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“aqueous auxin NAA at 1.0 m M showed both an initial surge in growth lasting 4–6 h followed by growth inhibition sustained at least as long as 24 h post‐treatment”
Claim · model-written summary
Auxin inhibition of leaf expansion was associated with smaller epidermal cells.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Organ / stage
- leafe1
- Treatment
- Auxine1
- Outcome
- epidermal cell areae1
- Direction
- smallere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“Auxin‐induced inhibition of leaf expansion was associated with smaller epidermal cell area”
Claim · model-written summary
Authors inferred that increasing leaf auxin first increases and then slows growth by inhibiting cell expansion.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Treatment
- leaf auxine1
- Outcome
- growthe1
- Qualifier
- inhibition of cell expansione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“increasing leaf auxin first increases growth and then slows growth through inhibition of cell expansion”
Claim · model-written summary
Excised leaf strips retained only the early growth response to auxin.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise0
- Organ / stage
- Excised leaf stripse1
- Outcome
- initial increased growth response to auxine1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“common bean ( Phaseolus vulgaris )”
e1“Excised leaf strips retain only the initial increased growth response to auxin and not the subsequent growth inhibition”
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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.