Abstract
Submergence tolerance of 13 doubled haploid lines of rice and their parents (submergence tolerant FR13A and submergence intolerant CT6241) was assessed using 2-week-old seedlings. Plants were scored for leaf senescence and percentage of seedlings that survived up to 15 d submergence, followed by a 12 d recovery period. Seven lines proved to be submergence tolerant, and six relatively intolerant. In all lines, activity of pyruvate decarboxylase (PDC), extracted from the apical 3-5 cm of root axes, decreased by 46-96 % and 38-76 %, respectively, during 5 or 10 d submergence under natural day/night conditions, compared with pre-submergence values (100 %). However, when the enzyme was extracted at night, submergence increased PDC activity of all rice lines (approx. 112 % on average), compared with pre-submergence values (100 %). The stimulating effect of the dark period on PDC activity was reproduced and amplified by submerging rice seedlings for up to 5 d in continuous darkness in water containing sub-ambient concentrations of oxygen (2.3 mg l(-1)). Such increased PDC activity was also observed in seedlings exposed to anoxia for 6 h (approx. 6-175 % higher than pre-submergence values). Irrespective of tolerance class, submergence decreased soluble protein concentrations under all conditions and sampling times. No positive correlation was found between PDC activity and tolerance of the various rice lines to submergence. However, PDC activity was slightly higher in submergence intolerant lines, compared with tolerant lines, under both dark submergence and anoxia. Such differences in PDC activity between the two groups of rice lines were not observed when they were submerged under the natural diurnal cycle. Increased PDC activity in roots at night demonstrated a probable incidence of tissue hypoxia or anoxia during submergence during each dark period.
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Claims 11
Claim · model-written summary
Seven rice lines were submergence tolerant and six relatively intolerant.
- Taxon
- Rice
Oryza sativat0 - Outcome
- submergence tolerante0
- Value
- Sevene0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seven lines proved to be submergence tolerant, and six relatively intolerant”
t0“Rice Lines”
Claim · model-written summary
Five days of submergence in natural day and night conditions reduced root PDC activity by 46–96%.
- Taxon
- RiceOryza sativat0
- Treatment
- 5 or 10 d submergencee0
- Gene
- pyruvate decarboxylase (PDC)e0
- Outcome
- activity of pyruvate decarboxylase (PDC)e0
- Direction
- decreasede0
- Value
- 46-96 %e0
- Comparator
- pre-submergence valuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“activity of pyruvate decarboxylase (PDC), extracted from the apical 3-5 cm of root axes, decreased by 46-96 % and 38-76 %, respectively, during 5 or 10 d submergence under natural day/night conditions, compared with pre-submergence values (100 %)”
t0“Rice Lines”
Claim · model-written summary
Ten days of submergence in natural day and night conditions reduced root PDC activity by 38–76%.
- Taxon
- RiceOryza sativat0
- Treatment
- 10 d submergencee0
- Gene
- pyruvate decarboxylase (PDC)e0
- Outcome
- activity of pyruvate decarboxylase (PDC)e0
- Direction
- decreasede0
- Value
- 38-76 %e0
- Comparator
- pre-submergence valuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“activity of pyruvate decarboxylase (PDC), extracted from the apical 3-5 cm of root axes, decreased by 46-96 % and 38-76 %, respectively, during 5 or 10 d submergence under natural day/night conditions, compared with pre-submergence values (100 %)”
t0“Rice Lines”
Claim · model-written summary
At night, submergence increased root PDC activity to approximately 112% of pre-submergence values.
- Taxon
- riceOryza sativae0
- Treatment
- submergencee0
- Gene
- PDCe0
- Outcome
- PDC activitye0
- Direction
- increasede0
- Value
- 112 %e0
- Comparator
- pre-submergence valuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when the enzyme was extracted at night, submergence increased PDC activity of all rice lines (approx. 112 % on average), compared with pre-submergence values (100 %)”
Claim · model-written summary
Continuous dark submergence under low oxygen reproduced and amplified the stimulation of PDC activity.
- Taxon
- riceOryza sativae0
- Treatment
- submerging rice seedlings for up to 5 d in continuous darkness in water containing sub-ambient concentrations of oxygen (2.3 mg l(-1))e0
- Gene
- PDCe0
- Outcome
- PDC activitye0
- Direction
- amplifiede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stimulating effect of the dark period on PDC activity was reproduced and amplified by submerging rice seedlings for up to 5 d in continuous darkness in water containing sub-ambient concentrations of oxygen (2.3 mg l(-1))”
Claim · model-written summary
Six hours of anoxia increased rice seedling PDC activity by approximately 6–175% relative to pre-submergence.
- Taxon
- riceOryza sativae1
- Treatment
- anoxia for 6 he0
- Gene
- PDCe0
- Outcome
- PDC activitye0
- Direction
- increasede0
- Value
- 6-175 %e0
- Comparator
- pre-submergence valuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased PDC activity was also observed in seedlings exposed to anoxia for 6 h (approx. 6-175 % higher than pre-submergence values)”
e1“rice seedlings”
Claim · model-written summary
Submergence reduced soluble protein concentration across all conditions and sampling times regardless of rice line tolerance.
- Taxon
- RiceOryza sativat0
- Treatment
- submergencee0
- Outcome
- soluble protein concentrationse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Irrespective of tolerance class, submergence decreased soluble protein concentrations under all conditions and sampling times”
t0“Rice Lines”
Claim · model-written summary
PDC activity was not positively correlated with submergence tolerance across rice lines.
- Taxon
- riceOryza sativae0
- Gene
- PDCe0
- Outcome
- tolerance of the various rice lines to submergencee0
- Direction
- No positive correlatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No positive correlation was found between PDC activity and tolerance of the various rice lines to submergence”
Claim · model-written summary
Under dark submergence and anoxia, intolerant rice lines had slightly higher PDC activity than tolerant lines.
- Taxon
- RiceOryza sativat0
- Material
- submergence intolerant linese0
- Gene
- PDCe0
- Outcome
- PDC activitye0
- Direction
- slightly highere0
- Comparator
- tolerant linese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PDC activity was slightly higher in submergence intolerant lines, compared with tolerant lines, under both dark submergence and anoxia”
t0“Rice Lines”
Claim · model-written summary
Under natural day and night submergence, tolerant and intolerant groups did not differ in PDC activity.
- Taxon
- riceOryza sativae0
- Gene
- PDCe0
- Outcome
- differences in PDC activitye0
- Direction
- not observede0
- Setting
- natural diurnal cyclee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such differences in PDC activity between the two groups of rice lines were not observed when they were submerged under the natural diurnal cycle”
Claim · model-written summary
Increased nighttime root PDC activity was interpreted as probable hypoxia or anoxia during each dark submergence period.
- Taxon
- RiceOryza sativat0
- Gene
- PDCe0
- Outcome
- probable incidence of tissue hypoxia or anoxiae0
- Qualifier
- during submergence during each dark periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased PDC activity in roots at night demonstrated a probable incidence of tissue hypoxia or anoxia during submergence during each dark period”
t0“Rice Lines”
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