Abstract
We investigated the kinds of active oxygen species leading to the destruction of chloroplast ultrastructure in salt-stressed rice plants. After the seedlings were grown for 3 wks, leaf segments (5 mm square) were cut from the middle portion of the 5th leaves. Leaf segments were incubated in 200 mM NaCl under dark or light conditions for 24 hr. The chlorophyll content in the leaf segments drastically decreased in light between 12- and 24 hr in 200 mM NaCl, but, no reduction was observed in the dark. In electron microscopic studies, 200 mM NaCl caused swelling of thylakoids and destruction of thylakoid membranes in light. On the other hand, no ultrastructural changes were observed under dark condition. In one experiment, leaf segments were incubated in 200 mM NaCl for 24 hr in light after preincubation with antioxidants for 12 hr in light. Pretreatment with ascorbate and benzoate, which scavenge H2O2 and ˁOH, respectively, effectively suppressed the reduction of chlorophyll content and the destruction of chloroplasts by NaCl in light. However, Tiron and DABCO, which scavenge O2- and 1O2, respectively, could not suppress the effects of salt stress in light. Fe-SOD activity was increased about eight time by salt stress (200 mM NaCl), but, catalase activity was reduced to 69% of the control and ascorbate peroxidase activity was not affected by NaCl. These results suggested that salt-induced injury in chloroplasts is dependent on light, and that H2O2 and ˁOH are responsible for the deleterious effects of salt stress on chlorophyll content and chloroplast ultrastructure.
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Claims 12
Claim · model-written summary
Chlorophyll content fell drastically between 12 and 24 hours in light with 200 mM NaCl.
- Taxon
- Rice
Oryza sativat0 - Organ / stage
- leaf segmentse0
- Treatment
- 200 mM NaCle0
- Outcome
- chlorophyll contente0
- Direction
- decreasede0
- Qualifier
- in light between 12- and 24 hre0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The chlorophyll content in the leaf segments drastically decreased in light between 12- and 24 hr in 200 mM NaCl”
t0“Rice Leaf Segments”
Claim · model-written summary
Chlorophyll content did not decline in darkness under salt treatment.
- Taxon
- RiceOryza sativat0
- Outcome
- reductione0
- Direction
- no reductione0
- Qualifier
- in the darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no reduction was observed in the dark”
t0“Rice Leaf Segments”
Claim · model-written summary
Salt caused thylakoid swelling and membrane destruction in light.
- Taxon
- RiceOryza sativat0
- Treatment
- 200 mM NaCle0
- Outcome
- swelling of thylakoids and destruction of thylakoid membranese0
- Qualifier
- in lighte0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“200 mM NaCl caused swelling of thylakoids and destruction of thylakoid membranes in light”
t0“Rice Leaf Segments”
Claim · model-written summary
Chloroplast ultrastructure did not change in darkness.
- Taxon
- RiceOryza sativat0
- Outcome
- ultrastructural changese0
- Qualifier
- under dark conditione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no ultrastructural changes were observed under dark condition”
t0“Rice Leaf Segments”
Claim · model-written summary
Ascorbate pretreatment suppressed salt induced chlorophyll loss and chloroplast destruction in light.
- Taxon
- RiceOryza sativat0
- Treatment
- Pretreatment with ascorbatee0
- Outcome
- reduction of chlorophyll content and the destruction of chloroplastse0
- Direction
- suppressede0
- Qualifier
- by NaCl in lighte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pretreatment with ascorbate and benzoate, which scavenge H2O2 and ˁOH, respectively, effectively suppressed the reduction of chlorophyll content and the destruction of chloroplasts by NaCl in light”
t0“Rice Leaf Segments”
Claim · model-written summary
Benzoate pretreatment suppressed salt induced chlorophyll loss and chloroplast destruction in light.
- Taxon
- RiceOryza sativat0
- Treatment
- benzoatee0
- Outcome
- reduction of chlorophyll content and the destruction of chloroplastse0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pretreatment with ascorbate and benzoate, which scavenge H2O2 and ˁOH, respectively, effectively suppressed the reduction of chlorophyll content and the destruction of chloroplasts by NaCl in light”
t0“Rice Leaf Segments”
Claim · model-written summary
Tiron did not suppress the salt stress effects in light.
- Taxon
- RiceOryza sativat0
- Treatment
- Tirone0
- Outcome
- effects of salt stresse0
- Direction
- could not suppresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tiron and DABCO, which scavenge O2- and 1O2, respectively, could not suppress the effects of salt stress in light”
t0“Rice Leaf Segments”
Claim · model-written summary
DABCO did not suppress the salt stress effects in light.
- Taxon
- RiceOryza sativat0
- Treatment
- DABCOe0
- Outcome
- effects of salt stresse0
- Direction
- could not suppresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tiron and DABCO, which scavenge O2- and 1O2, respectively, could not suppress the effects of salt stress in light”
t0“Rice Leaf Segments”
Claim · model-written summary
Salt increased Fe-SOD activity about eightfold.
- Taxon
- RiceOryza sativat0
- Treatment
- salt stress (200 mM NaCl)e0
- Gene
- Fe-SODe0
- Outcome
- Fe-SOD activitye0
- Direction
- increasede0
- Value
- about eight timee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fe-SOD activity was increased about eight time by salt stress (200 mM NaCl)”
t0“Rice Leaf Segments”
Claim · model-written summary
Salt reduced catalase activity to 69% of control.
- Taxon
- RiceOryza sativat0
- Gene
- catalasee0
- Outcome
- catalase activitye0
- Direction
- reducede0
- Value
- 69%e0
- Comparator
- the controle0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“catalase activity was reduced to 69% of the control”
t0“Rice Leaf Segments”
Claim · model-written summary
Salt did not affect ascorbate peroxidase activity.
- Taxon
- RiceOryza sativat0
- Treatment
- NaCle0
- Gene
- ascorbate peroxidasee0
- Outcome
- ascorbate peroxidase activitye0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ascorbate peroxidase activity was not affected by NaCl”
t0“Rice Leaf Segments”
Claim · model-written summary
The authors attributed salt injury in chloroplasts to light dependence and H2O2 and ˁOH.
- Taxon
- RiceOryza sativat0
- Compound
- H2O2 and ˁOHe0
- Outcome
- salt-induced injury in chloroplastse0
- Qualifier
- dependent on lighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“salt-induced injury in chloroplasts is dependent on light, and that H2O2 and ˁOH are responsible for the deleterious effects of salt stress on chlorophyll content and chloroplast ultrastructure”
t0“Rice Leaf Segments”
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