Abstract
We investigated the interaction of Ca2+ and auxin on root elongation in seedlings of Zea mays L. The seedlings were raised either in the presence of Ca2+ (high calcium; HC = imbibed and raised in 10 millimolar CaCl2), in the absence of additional Ca2+ (intermediate calcium; IC = imbibed and raised in distilled H2O, calcium supply from seed only), or without additional Ca2+ and subsequently depleting them of Ca2+ (low calcium; LC = imbibed and raised in distilled H2O and subsequently treated with 1 millimolar ethyleneglycol-bis-[beta-aminoethylether]-N,N,N',N'-tetraacetic acid [EGTA]). Exposure of roots of either HC or IC seedlings to auxin concentrations from 0.1 to 10 micromolar resulted in strong inhibition of elongation. In roots of LC seedlings, on the other hand, auxin concentrations as high as 10 micromolar caused only slight inhibition of elongation. Adding 0.5 millimolar Ca2+ to LC roots in the presence of IAA allowed normal expression of the inhibitory action of the hormone. Inhibition of elongation in IC roots by indoleacetic acid was reversible upon treatment of the roots with 1 millimolar EGTA. The inhibitory action of auxin could then be re-established by supplying 0.5 millimolar Ca2+. The data indicate that Ca2+ may be necessary to the growth-regulating action of auxin. The significance of this finding is discussed with respect to the potential role of Ca2+ as a second messenger of auxin action and the relevance of this model to recent evidence for gravi-induced redistribution of Ca2+ and its role in establishing gravitropic curvature.
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Claims 7
Claim · model-written summary
Auxin at 0.1 to 10 micromolar strongly inhibited root elongation in high-calcium seedlings.
- Material
- HCe1
- Organ / stage
- rootse1
- Treatment
- auxin concentrations from 0.1 to 10 micromolare1
- Outcome
- elongatione1
- Direction
- inhibitione1
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“Exposure of roots of either HC or IC seedlings to auxin concentrations from 0.1 to 10 micromolar resulted in strong inhibition of elongation.”
Claim · model-written summary
Auxin at 0.1 to 10 micromolar strongly inhibited root elongation in intermediate-calcium seedlings.
- Material
- ICe1
- Organ / stage
- rootse1
- Treatment
- auxin concentrations from 0.1 to 10 micromolare1
- Outcome
- elongatione1
- Direction
- inhibitione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“Exposure of roots of either HC or IC seedlings to auxin concentrations from 0.1 to 10 micromolar resulted in strong inhibition of elongation.”
Claim · model-written summary
Auxin up to 10 micromolar caused only slight root elongation inhibition in low-calcium seedlings.
- Material
- LCe1
- Organ / stage
- rootse1
- Treatment
- auxin concentrations as high as 10 micromolare1
- Outcome
- elongatione1
- Direction
- slight inhibitione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“In roots of LC seedlings, on the other hand, auxin concentrations as high as 10 micromolar caused only slight inhibition of elongation.”
Claim · model-written summary
Adding calcium to low-calcium roots in IAA restored normal auxin inhibition of elongation.
- Material
- LCe1
- Organ / stage
- rootse1
- Treatment
- Adding 0.5 millimolar Ca2+e1
- Outcome
- inhibitory action of the hormonee1
- Direction
- normal expressione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“Adding 0.5 millimolar Ca2+ to LC roots in the presence of IAA allowed normal expression of the inhibitory action of the hormone.”
Claim · model-written summary
EGTA treatment reversed indoleacetic-acid inhibition of root elongation in intermediate-calcium seedlings.
- Material
- ICe1
- Organ / stage
- rootse1
- Treatment
- treatment of the roots with 1 millimolar EGTAe1
- Outcome
- Inhibition of elongatione1
- Direction
- reversiblee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“Inhibition of elongation in IC roots by indoleacetic acid was reversible upon treatment of the roots with 1 millimolar EGTA.”
Claim · model-written summary
Supplying calcium re-established auxin inhibition after EGTA reversal.
- Treatment
- supplying 0.5 millimolar Ca2+e1
- Outcome
- inhibitory action of auxine1
- Direction
- re-establishede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“The inhibitory action of auxin could then be re-established by supplying 0.5 millimolar Ca2+.”
Claim · model-written summary
The authors infer that calcium may be required for auxin to regulate growth.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings of Zea mays L.”
e1“Ca2+ may be necessary to the growth-regulating action of auxin”
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
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