Abstract
A rice suspension cell culture system has been established to study how sugar depletion regulates alpha-amylase expression, carbohydrate metabolism, and other physiological and cellular changes. It is shown here that a group of 44 kDa alpha-amylases are constitutively expressed whether or not the cells are starved of sucrose. However, expression of a new group of alpha-amylases of 46 kDa is dramatically induced when cells are starved of sucrose. Cellular sugar and starch were rapidly consumed and metabolic activity was decreased in the starved cells. Extensive autophagy also occurred in the starved cells, which caused an increase in vacuolar volume and degradation of cytoplasmic constituents including amyloplasts. Immunocytochemical studies revealed that alpha-amylases are localized in starch granules within amyloplasts, in cell walls, and in some of the vacuoles. The presence of putative signal sequences in the N-termini of nine rice alpha-amylases suggests hitherto unidentified pathways for import of alpha-amylases into amyloplasts. The studies show that differential alpha-amylase expression, carbohydrate metabolism, metabolic activity, and vacuolar autophagy are coordinately regulated by the sugar level in the medium. As the starved suspension cells exhibit some sugar-regulated characteristics of alpha-amylase expression in germinating rice embryos as well as physiological changes similar to those in senescing cells, this system represents an ideal tool for studying cellular, biochemical, and molecular biological aspects of alpha-amylase gene regulation, carbohydrate metabolism, senescence, and protein targeting in plants.
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Claims 13
Claim · model-written summary
The 44 kDa alpha-amylases were expressed regardless of sucrose starvation.
- Taxon
- rice
Oryza sativat0 - Gene
- 44 kDa alpha-amylasese0
- Outcome
- constitutively expressede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a group of 44 kDa alpha-amylases are constitutively expressed whether or not the cells are starved of sucrose”
t0“rice”
Claim · model-written summary
Sucrose starvation strongly induced expression of the 46 kDa alpha-amylases.
- Taxon
- riceOryza sativat0
- Treatment
- starved of sucrosee0
- Gene
- alpha-amylases of 46 kDae0
- Outcome
- expressione0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of a new group of alpha-amylases of 46 kDa is dramatically induced when cells are starved of sucrose”
t0“rice”
Claim · model-written summary
Starved cells rapidly consumed cellular sugar and starch.
- Taxon
- riceOryza sativat0
- Outcome
- Cellular sugar and starche0
- Direction
- consumede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cellular sugar and starch were rapidly consumed and metabolic activity was decreased in the starved cells”
t0“rice”
Claim · model-written summary
Metabolic activity decreased in starved cells.
- Taxon
- riceOryza sativat0
- Outcome
- metabolic activitye0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“metabolic activity was decreased in the starved cells”
t0“rice”
Claim · model-written summary
Extensive autophagy occurred in starved cells.
- Taxon
- riceOryza sativat0
- Outcome
- Extensive autophagye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Extensive autophagy also occurred in the starved cells”
t0“rice”
Claim · model-written summary
Autophagy increased vacuolar volume in starved cells.
- Taxon
- riceOryza sativat0
- Outcome
- vacuolar volumee0
- Direction
- increasee0
- Qualifier
- autophagye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Extensive autophagy also occurred in the starved cells, which caused an increase in vacuolar volume”
t0“rice”
Claim · model-written summary
Autophagy degraded cytoplasmic constituents including amyloplasts.
- Taxon
- riceOryza sativat0
- Outcome
- degradation of cytoplasmic constituents including amyloplastse0
- Qualifier
- autophagye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“autophagy also occurred in the starved cells, which caused an increase in vacuolar volume and degradation of cytoplasmic constituents including amyloplasts”
t0“rice”
Claim · model-written summary
Alpha-amylases localized in amyloplast starch granules, cell walls and some vacuoles.
- Taxon
- riceOryza sativat0
- Gene
- alpha-amylasese0
- Outcome
- localized in starch granules within amyloplasts, in cell walls, and in some of the vacuolese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alpha-amylases are localized in starch granules within amyloplasts, in cell walls, and in some of the vacuoles”
t0“rice”
Claim · model-written summary
Signal sequences in nine rice alpha-amylases suggest unknown amyloplast import pathways.
- Taxon
- riceOryza sativae0
- Gene
- rice alpha-amylasese0
- Outcome
- pathways for import of alpha-amylases into amyloplastse0
- Qualifier
- putative signal sequencese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“putative signal sequences in the N-termini of nine rice alpha-amylases suggests hitherto unidentified pathways for import of alpha-amylases into amyloplasts”
Claim · model-written summary
Sugar level coordinately regulated amylase expression, carbohydrate metabolism, metabolic activity and vacuolar autophagy.
- Taxon
- riceOryza sativat0
- Treatment
- sugar level in the mediume0
- Outcome
- differential alpha-amylase expression, carbohydrate metabolism, metabolic activity, and vacuolar autophagye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“differential alpha-amylase expression, carbohydrate metabolism, metabolic activity, and vacuolar autophagy are coordinately regulated by the sugar level in the medium”
t0“rice”
Claim · model-written summary
Starved cells resembled germinating rice embryos in sugar-regulated amylase expression.
- Taxon
- riceOryza sativae0
- Outcome
- sugar-regulated characteristics of alpha-amylase expressione0
- Comparator
- germinating rice embryose0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“starved suspension cells exhibit some sugar-regulated characteristics of alpha-amylase expression in germinating rice embryos”
Claim · model-written summary
Starved cells showed physiological changes similar to senescing cells.
- Taxon
- riceOryza sativat0
- Outcome
- physiological changese0
- Comparator
- senescing cellse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“physiological changes similar to those in senescing cells”
t0“rice”
Claim · model-written summary
The suspension system was presented as a tool for studying amylase regulation, metabolism, senescence and protein targeting.
- Taxon
- riceOryza sativat0
- Outcome
- ideal toole0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this system represents an ideal tool for studying cellular, biochemical, and molecular biological aspects of alpha-amylase gene regulation, carbohydrate metabolism, senescence, and protein targeting in plants”
t0“rice”
The same questions in other papers
sucrose · molecular: expression · Oryza sativa (rice)Positive and negative results
13 papers in the same direction as this paper · 4 in the opposite direction
- positive
- positive
- no effect
14 papers more in this group
See all 18 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.