Abstract
The negative effect on plant responses are expected due to increased amounts of ultraviolet-B (UV-B) radiation reaching on the Earth's surface by stratospheric ozone depletion. Cytokinins (CKs) are essential phytohormones in plant growth and development. Perusal of relevant literature reveals that CKs mitigate the oxidative damage caused by abiotic stresses like salt, drought, high temperature and heavy metal due to their antioxidant effects. However, very few reports are available on the interaction of CKs with UV-B stress on the expansion growth of the cucumber cotyledons. CKs induced the expansion growth of the excised cucumber cotyledons in the darkness. CKs induced expansion growth of cucumber cotyledons in darkness was inhibited by supplemental UV-B. UV-B radiation enhanced the level of oxyradicals like superoxide and hydroxide radicals in the excised cucumber cotyledons, which was evident by EPR spectroscopy. CKs like Zeatin, TDZ, BAP and FAP reduced the level of oxyradicals produced in the dark grown cucumber cotyledons, while promoting the expansion growth of the cotyledons. Production of oxyradical in UV-B exposed cotyledons showed that these oxyradicals might partially account for inhibition of expansion growth. Since considerable amount of oxyradicals were quenched by CKs at higher concentrations (10 and 20 g/ml) it partially restores the inhibition of expansion growth caused by UV-B stress. It indicates that overproduction of oxyradicals by UV-B could not be entirely responsible for the inhibition of CKs induced expansion growth of cotyledons; which might be caused by some other physiological changes caused by UV-B irradiation in addition to the production of oxyradicals. UV-B is also known to inactivate protein inhibitor of peroxidase in cucumber cotyledons. This may reduce the antioxidants defence and enhance the damaging effects of oxyradicals for the growth of cotyledons.
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Claims 10
Claim · model-written summary
Cytokinins induced expansion of excised cucumber cotyledons in darkness.
- Taxon
- cucumber
Cucumis sativuse0 - Organ / stage
- cotyledonse0
- Treatment
- CKse0
- Outcome
- expansion growthe0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CKs induced the expansion growth of the excised cucumber cotyledons in the darkness”
Claim · model-written summary
Supplemental UV-B inhibited cytokinin-induced cucumber cotyledon expansion in darkness.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- cotyledonse0
- Treatment
- supplemental UV-Be0
- Outcome
- expansion growthe0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CKs induced expansion growth of cucumber cotyledons in darkness was inhibited by supplemental UV-B”
Claim · model-written summary
UV-B enhanced superoxide and hydroxide radical levels in excised cucumber cotyledons.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- cotyledonse0
- Treatment
- UV-B radiatione0
- Outcome
- level of oxyradicals like superoxide and hydroxide radicalse0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UV-B radiation enhanced the level of oxyradicals like superoxide and hydroxide radicals in the excised cucumber cotyledons”
Claim · model-written summary
Zeatin reduced oxyradical levels in dark-grown cucumber cotyledons while promoting expansion.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- cotyledonse0
- Treatment
- Zeatine0
- Outcome
- level of oxyradicalse0
- Direction
- reducede0
- Qualifier
- dark growne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CKs like Zeatin, TDZ, BAP and FAP reduced the level of oxyradicals produced in the dark grown cucumber cotyledons, while promoting the expansion growth of the cotyledons”
Claim · model-written summary
TDZ reduced oxyradical levels in dark-grown cucumber cotyledons while promoting expansion.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- cotyledonse0
- Treatment
- TDZe0
- Outcome
- level of oxyradicalse0
- Direction
- reducede0
- Qualifier
- dark growne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CKs like Zeatin, TDZ, BAP and FAP reduced the level of oxyradicals produced in the dark grown cucumber cotyledons, while promoting the expansion growth of the cotyledons”
Claim · model-written summary
BAP reduced oxyradical levels in dark-grown cucumber cotyledons while promoting expansion.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- cotyledonse0
- Treatment
- BAPe0
- Outcome
- level of oxyradicalse0
- Direction
- reducede0
- Qualifier
- dark growne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CKs like Zeatin, TDZ, BAP and FAP reduced the level of oxyradicals produced in the dark grown cucumber cotyledons, while promoting the expansion growth of the cotyledons”
Claim · model-written summary
FAP reduced oxyradical levels in dark-grown cucumber cotyledons while promoting expansion.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- cotyledonse0
- Treatment
- FAPe0
- Outcome
- level of oxyradicalse0
- Direction
- reducede0
- Qualifier
- dark growne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CKs like Zeatin, TDZ, BAP and FAP reduced the level of oxyradicals produced in the dark grown cucumber cotyledons, while promoting the expansion growth of the cotyledons”
Claim · model-written summary
Higher cytokinin concentrations quenched oxyradicals and partly restored UV-B-inhibited cucumber cotyledon expansion.
- Taxon
- cucumberCucumis sativust0
- Organ / stage
- cotyledonst0
- Treatment
- CKs at higher concentrations (10 and 20 g/ml)e0
- Outcome
- inhibition of expansion growthe0
- Direction
- partially restorese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“considerable amount of oxyradicals were quenched by CKs at higher concentrations (10 and 20 g/ml) it partially restores the inhibition of expansion growth caused by UV-B stress”
t0“cucumber cotyledons”
Claim · model-written summary
Authors suggest UV-B-induced oxyradicals only partly explain inhibited cucumber cotyledon expansion.
- Taxon
- cucumberCucumis sativust0
- Outcome
- inhibition of expansion growthe0
- Qualifier
- these oxyradicals might partially accounte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these oxyradicals might partially account for inhibition of expansion growth”
t0“cucumber cotyledons”
Claim · model-written summary
Authors suggest additional UV-B-induced physiological changes may inhibit cytokinin-induced cotyledon expansion.
- Taxon
- cucumberCucumis sativust0
- Outcome
- physiological changes caused by UV-B irradiatione0
- Qualifier
- in addition to the production of oxyradicalse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which might be caused by some other physiological changes caused by UV-B irradiation in addition to the production of oxyradicals”
t0“cucumber cotyledons”
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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.