Abstract
We present evidence to show that the alpha-amylase gene family in rice is under two different modes of regulation: 1) hormonal regulation in germinating seeds, and 2) metabolic repression in cultured cells by available carbohydrate nutrients. Expression of alpha-amylase genes in deembryoed rice seeds is known to be induced by exogenous gibberellic acid. On the other hand, expression of alpha-amylase genes in suspension-cultured cells is induced by the deprivation of carbohydrate nutrient. A lag period of 2-4 h is required for the induction of alpha-amylase mRNA in sucrose-depleted medium. The induction of alpha-amylase expression is extraordinarily high and levels of alpha-amylase mRNA can be increased 8-20-folds after 24 h of sucrose starvation. The synthesis and secretion of alpha-amylase is also dependent upon the level of carbon source. The derepression or repression of alpha-amylase synthesis can be readily reversed by the deprivation or replenishment of sucrose in the medium, respectively. Glucose and fructose exert a repression on the alpha-amylase synthesis similar to that of sucrose. A hypothesis that explains the induction of alpha-amylase synthesis by carbohydrate starvation is proposed. Our data have suggested a hitherto undiscovered, potentially important control mechanism of carbohydrate metabolism in higher plants.
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Claims 9
Claim · model-written summary
Exogenous gibberellic acid induces alpha-amylase gene expression in deembryoed rice seeds.
- Taxon
- rice
Oryza sativae0 - Organ / stage
- deembryoed rice seedse0
- Treatment
- exogenous gibberellic acide0
- Gene
- alpha-amylase genese0
- Outcome
- Expression of alpha-amylase genese0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expression of alpha-amylase genes in deembryoed rice seeds is known to be induced by exogenous gibberellic acid.”
Claim · model-written summary
Carbohydrate deprivation induces alpha-amylase expression in rice cultured cells.
- Taxon
- riceOryza sativat0
- Organ / stage
- suspension-cultured cellse0
- Treatment
- deprivation of carbohydrate nutriente0
- Gene
- alpha-amylase genese0
- Outcome
- expression of alpha-amylase genese0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of alpha-amylase genes in suspension-cultured cells is induced by the deprivation of carbohydrate nutrient.”
t0“rice”
Claim · model-written summary
Induction of alpha-amylase mRNA after sucrose depletion required 2–4 h.
- Taxon
- riceOryza sativat0
- Treatment
- sucrose-depleted mediume0
- Gene
- alpha-amylase mRNAe0
- Outcome
- lag periode0
- Value
- 2-4 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A lag period of 2-4 h is required for the induction of alpha-amylase mRNA in sucrose-depleted medium.”
t0“rice”
Claim · model-written summary
Alpha-amylase mRNA rose 8–20-fold after 24 h of sucrose starvation.
- Taxon
- riceOryza sativat0
- Treatment
- sucrose starvatione0
- Gene
- alpha-amylase mRNAe0
- Outcome
- levels of alpha-amylase mRNAe0
- Direction
- increasede0
- Value
- 8-20-foldse0
- Qualifier
- after 24 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“levels of alpha-amylase mRNA can be increased 8-20-folds after 24 h of sucrose starvation.”
t0“rice”
Claim · model-written summary
Alpha-amylase synthesis and secretion depended on carbon-source level.
- Taxon
- riceOryza sativat0
- Treatment
- level of carbon sourcee0
- Gene
- alpha-amylasee0
- Outcome
- synthesis and secretion of alpha-amylasee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The synthesis and secretion of alpha-amylase is also dependent upon the level of carbon source.”
t0“rice”
Claim · model-written summary
Sucrose deprivation derepressed alpha-amylase synthesis.
- Taxon
- riceOryza sativat0
- Treatment
- deprivatione0
- Gene
- alpha-amylasee0
- Outcome
- alpha-amylase synthesise0
- Direction
- derepressione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The derepression or repression of alpha-amylase synthesis can be readily reversed by the deprivation or replenishment of sucrose in the medium, respectively.”
t0“rice”
Claim · model-written summary
Sucrose replenishment repressed alpha-amylase synthesis.
- Taxon
- riceOryza sativat0
- Treatment
- replenishment of sucrosee0
- Gene
- alpha-amylasee0
- Outcome
- alpha-amylase synthesise0
- Direction
- repressione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The derepression or repression of alpha-amylase synthesis can be readily reversed by the deprivation or replenishment of sucrose in the medium, respectively.”
t0“rice”
Claim · model-written summary
Glucose repressed alpha-amylase synthesis similarly to sucrose.
- Taxon
- riceOryza sativat0
- Treatment
- Glucosee0
- Gene
- alpha-amylasee0
- Outcome
- alpha-amylase synthesise0
- Direction
- repressione0
- Comparator
- sucrosee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Glucose and fructose exert a repression on the alpha-amylase synthesis similar to that of sucrose.”
t0“rice”
Claim · model-written summary
Fructose repressed alpha-amylase synthesis similarly to sucrose.
- Taxon
- riceOryza sativat0
- Treatment
- fructosee0
- Gene
- alpha-amylasee0
- Outcome
- alpha-amylase synthesise0
- Direction
- repressione0
- Comparator
- sucrosee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Glucose and fructose exert a repression on the alpha-amylase synthesis similar to that of sucrose.”
t0“rice”
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