Abstract
Biochemical analysis of amylose-extender (ae) mutant of rice (Oryza sativa) revealed that the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12. The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution. The ae mutation caused a dramatic reduction in the activity of BEIIb. The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity. In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation. Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI. These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.
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Claims 8
Claim · model-written summary
The ae mutation reduced short amylopectin chains of degree of polymerization 17 or less, especially 8 to 12, in rice endosperm.
- Taxon
- rice
Oryza sativat0 - Treatment
- the mutatione0
- Gene
- starch-branching enzyme IIb (BEIIb)e0
- Outcome
- short chains with degree of polymerization of 17 or lesse0
- Direction
- reducinge0
- Qualifier
- greatest decrease in chains with degree of polymerization of 8 to 12e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the mutation in the gene for starch-branching enzyme IIb (BEIIb) specifically altered the structure of amylopectin in the endosperm by reducing short chains with degree of polymerization of 17 or less, with the greatest decrease in chains with degree of polymerization of 8 to 12.”
t0“rice endosperm”
Claim · model-written summary
The extent of the amylopectin change correlated with starch-granule gelatinization properties measured by solubility in urea.
- Taxon
- riceOryza sativat0
- Organ / stage
- starch granulese0
- Outcome
- gelatinization properties of the starch granulese0
- Qualifier
- solubility in urea solutione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The extent of such change was correlated with the gelatinization properties of the starch granules, as determined in terms of solubility in urea solution.”
t0“rice endosperm”
Claim · model-written summary
The ae mutation dramatically reduced BEIIb activity.
- Taxon
- riceOryza sativat0
- Treatment
- ae mutatione0
- Gene
- BEIIbe0
- Outcome
- activity of BEIIbe0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The ae mutation caused a dramatic reduction in the activity of BEIIb.”
t0“rice endosperm”
Claim · model-written summary
SSI activity was significantly lower in the ae mutant than in wild type.
- Taxon
- riceOryza sativat0
- Treatment
- ae mutante0
- Gene
- soluble starch synthase I (SSI)e0
- Outcome
- activity of soluble starch synthase I (SSI)e0
- Direction
- lowere0
- Comparator
- wild typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activity of soluble starch synthase I (SSI) in the ae mutant was significantly lower than in the wild type, suggesting that the mutation had a pleiotropic effect on the SSI activity.”
t0“rice endosperm”
Claim · model-written summary
Activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, and isoamylase were unaffected by the ae mutation.
- Taxon
- riceOryza sativat0
- Treatment
- the mutatione0
- Outcome
- activities of BEI, BEIIa, ADP-Glc pyrophosphorylasee0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation.”
t0“rice endosperm”
Claim · model-written summary
Activities of pullulanase and Suc synthase were unaffected by the ae mutation.
- Taxon
- riceOryza sativat0
- Treatment
- the mutatione0
- Outcome
- pullulanase, and Suc synthasee0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, the activities of BEI, BEIIa, ADP-Glc pyrophosphorylase, isoamylase, isoamylase, pullulanase, and Suc synthase were not affected by the mutation.”
t0“rice endosperm”
Claim · model-written summary
The authors conclude that BEIIa and BEI cannot complement BEIIb function.
- Taxon
- riceOryza sativat0
- Gene
- BEIIbe0
- Outcome
- function of BEIIb cannot be complementede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Therefore, it is stressed that the function of BEIIb cannot be complemented by BEIIa and BEI.”
t0“rice endosperm”
Claim · model-written summary
The authors infer that BEIIb specifically transfers short chains that SS may extend into A and B(1) amylopectin chains.
- Taxon
- riceOryza sativae0
- Gene
- BEIIbe0
- Outcome
- transfer of short chainse0
- Qualifier
- might then be extended by SS to form the A and B(1) chainse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results strongly suggest that BEIIb plays a specific role in the transfer of short chains, which might then be extended by SS to form the A and B(1) chains of amylopectin cluster in rice endosperm.”
The same questions in other papers
loss of function · physiology: enzyme activity · Oryza sativa (rice)Positive and negative results
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- positive
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See all 9 papers →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.