Abstract
We investigated the mechanisms of increased sensitivity to Na+ in the apical and basal regions of the rice leaf under salinity. Three-week-old plants were treated with 200 mM NaCl in hydroponic culture for 3 d. Segments 6 cm in length were obtained from the apical and basal regions of the fully expanded uppermost leaves (6th leaf blades) as old and young tissues, respectively. In the plants exposed to 200 mM NaCl, Nitro blue tetrazolium (NBT) reducing activity, and H2O2 and Malondialdehyde (MDA) contents significantly increased, accompanied by the swelling of thylakoids and destruction of thylakoid membranes in the apical regions. However, no indication of oxidative damages was observed in the basal region, even though the Na+ content in the basal region was comparable to that in the apical region. In the apical region, the capacity to scavenge H2O2 was lower than that in the basal region due to decrease in the constitutive levels of ascorbate peroxidase and guaiacol peroxidase. In addition, the activities of antioxidant enzymes except superoxide dismutase and guaiacol peroxidase decreased drastically after 48 hr of exposure to NaCl. By contrast, the activities of catalase and glutathione reductase in the basal region increased compared with those in the control, and other antioxidant enzymes did not decrease under salinity during the experimental period. These results suggest that the capacity to scavenge reactive oxygen species decreased with age, and thus the apical region of the leaf blade suffered severer damage by Na+ than the basal region.
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Claims 7
Claim · model-written summary
NaCl exposure significantly increased NBT reducing activity, H2O2 and MDA contents in apical rice leaf regions.
- Taxon
- Rice
Oryza sativat0 - Organ / stage
- apical regionse1
- Treatment
- 200 mM NaCle1
- Outcome
- Nitro blue tetrazolium (NBT) reducing activity, and H2O2 and Malondialdehyde (MDA) contentse1
- Direction
- significantly increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“In the plants exposed to 200 mM NaCl, Nitro blue tetrazolium (NBT) reducing activity, and H2O2 and Malondialdehyde (MDA) contents significantly increased, accompanied by the swelling of thylakoids and destruction of thylakoid membranes in the apical regions”
t0“Basal Regions of Rice Leaf”
Claim · model-written summary
No oxidative damage was observed in the basal region of rice leaves under salinity, although Na+ content was comparable to the apical region.
- Taxon
- RiceOryza sativat0
- Organ / stage
- basal regione2
- Outcome
- no indication of oxidative damagese2
- Qualifier
- even though the Na+ content in the basal region was comparable to that in the apical regione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“no indication of oxidative damages was observed in the basal region, even though the Na+ content in the basal region was comparable to that in the apical region”
t0“Basal Regions of Rice Leaf”
Claim · model-written summary
The apical region had lower H2O2 scavenging capacity than the basal region, attributed to lower constitutive ascorbate and guaiacol peroxidase levels.
- Taxon
- RiceOryza sativat0
- Organ / stage
- apical regione3
- Gene
- ascorbate peroxidase and guaiacol peroxidasee3
- Outcome
- the capacity to scavenge H2O2 was lowere3
- Direction
- lowere3
- Comparator
- basal regione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“In the apical region, the capacity to scavenge H2O2 was lower than that in the basal region due to decrease in the constitutive levels of ascorbate peroxidase and guaiacol peroxidase”
t0“Basal Regions of Rice Leaf”
Claim · model-written summary
Antioxidant enzyme activities, except SOD and guaiacol peroxidase, decreased drastically after 48 hr of NaCl exposure.
- Taxon
- RiceOryza sativat0
- Treatment
- exposure to NaCle4
- Outcome
- the activities of antioxidant enzymese4
- Direction
- decreasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“the activities of antioxidant enzymes except superoxide dismutase and guaiacol peroxidase decreased drastically after 48 hr of exposure to NaCl”
t0“Basal Regions of Rice Leaf”
Claim · model-written summary
Catalase and glutathione reductase activities increased in the basal region under salinity compared with the control.
- Taxon
- RiceOryza sativat0
- Organ / stage
- basal regione5
- Treatment
- salinitye6
- Outcome
- the activities of catalase and glutathione reductasee5
- Direction
- increasede5
- Comparator
- controle5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“the activities of catalase and glutathione reductase in the basal region increased compared with those in the control”
e6“other antioxidant enzymes did not decrease under salinity during the experimental period”
t0“Basal Regions of Rice Leaf”
Claim · model-written summary
Other antioxidant enzymes did not decrease under salinity during the experimental period.
- Taxon
- RiceOryza sativat0
- Treatment
- salinitye6
- Outcome
- other antioxidant enzymese6
- Direction
- did not decreasee6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“other antioxidant enzymes did not decrease under salinity during the experimental period”
t0“Basal Regions of Rice Leaf”
Claim · model-written summary
The capacity to scavenge reactive oxygen species decreased with age, so apical leaf regions suffered more Na+ damage than basal regions (authors suggest).
- Taxon
- RiceOryza sativat0
- Organ / stage
- apical region of the leaf bladee7
- Outcome
- capacity to scavenge reactive oxygen speciese7
- Direction
- decreasede7
- Qualifier
- with agee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“the capacity to scavenge reactive oxygen species decreased with age, and thus the apical region of the leaf blade suffered severer damage by Na+ than the basal region”
t0“Basal Regions of Rice Leaf”
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