Abstract
The effect of 253.7 nm ultraviolet radiation on elongation growth, medium acidification and changes in electric potential difference between vacuole and external medium in cells of maize ( Zea mays L.) coleoptile segments was investigated. It was found that irradiation with 390, 1170, 3900 and 5 850 J m −2 UV‐C (ultraviolet radiation 253.7 nm) inhibited elongation growth, whereas at 195 J m −2 stimulation of growth was observed. The administration of IAA (10 −5 M ) to the incubation medium of coleoptile segments partially abolished the inhibitory effect of UV‐C. The pH of the incubation medium, measured simultaneously with growth, showed that the exposure of the segments to UV‐C caused inhibition of H + ‐extrusion (or stimulation of H + uptake). The presence of IAA (10 −5 M ) in the incubation medium promoted (except after 5850 J m −2 irradiation) H + ‐extrusion to a level comparable with that produced by IAA in non‐irradiated segments. In UV‐C irradiated segments the potential difference underwent significant alterations. Irradiation of coleoptile segments with 390 J m −2 caused a transient depolarization, which was fully reversible within 30 min, while at higher doses depolarization was irreversible. The hyperpolarization of the membrane potential (MP) in cells of maize coleoptile induced by IAA was completely nullified by subsequent irradiation with UV‐C. It is suggested that UV‐C inhibited IAA‐induced growth by a mechanism independent of cell wall acidification.
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Claims 8
Claim · model-written summary
Higher UV-C doses inhibited maize coleoptile elongation.
- Organ / stage
- coleoptile segmentse1
- Treatment
- 390, 1170, 3900 and 5 850 J m −2 UV‐Ce0
- Outcome
- elongation growthe0
- Direction
- inhibitede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“irradiation with 390, 1170, 3900 and 5 850 J m −2 UV‐C (ultraviolet radiation 253.7 nm) inhibited elongation growth”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
UV-C at 195 J m −2 stimulated growth.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at 195 J m −2 stimulation of growth was observed”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
IAA partly relieved UV-C growth inhibition.
- Treatment
- IAA (10 −5 M )e0
- Outcome
- inhibitory effect of UV‐Ce0
- Direction
- partially abolishede0
- Comparator
- UV‐Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The administration of IAA (10 −5 M ) to the incubation medium of coleoptile segments partially abolished the inhibitory effect of UV‐C”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
UV-C inhibited proton extrusion or stimulated uptake.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exposure of the segments to UV‐C caused inhibition of H + ‐extrusion (or stimulation of H + uptake)”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
IAA promoted proton extrusion except after the highest irradiation dose.
- Treatment
- IAA (10 −5 M )e0
- Outcome
- H + ‐extrusione0
- Direction
- promotede0
- Qualifier
- except after 5850 J m −2 irradiatione0
- Comparator
- IAA in non‐irradiated segmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IAA (10 −5 M ) in the incubation medium promoted (except after 5850 J m −2 irradiation) H + ‐extrusion to a level comparable with that produced by IAA in non‐irradiated segments”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
UV-C at 390 J m −2 caused reversible membrane depolarization.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Irradiation of coleoptile segments with 390 J m −2 caused a transient depolarization, which was fully reversible within 30 min”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
Higher UV-C doses caused irreversible depolarization.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at higher doses depolarization was irreversible”
e1“maize ( Zea mays L.) coleoptile segments”
Claim · model-written summary
UV-C nullified IAA-induced membrane hyperpolarization.
- Treatment
- irradiation with UV‐Ce0
- Outcome
- hyperpolarization of the membrane potentiale0
- Direction
- completely nullifiede0
- Comparator
- IAAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The hyperpolarization of the membrane potential (MP) in cells of maize coleoptile induced by IAA was completely nullified by subsequent irradiation with UV‐C”
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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.