Abstract
Sucrose synthase (Sus) is a key enzyme of sucrose metabolism. Two Sus-encoding genes (Sus1 and Sus2) from Arabidopsis thaliana were found to be profoundly and differentially regulated in leaves exposed to environmental stresses (cold stress, drought or O2 deficiency). Transcript levels of Sus1 increased on exposure to cold and drought, whereas Sus2 mRNA was induced specifically by O2 deficiency. Both cold and drought exposures induced the accumulation of soluble sugars and caused a decrease in leaf osmotic potential, whereas O2 deficiency was characterized by a nearly complete depletion in sugars. Feeding abscisic acid (ABA) to detached leaves or subjecting Arabidopsis ABA-deficient mutants to cold stress conditions had no effect on the expression profiles of Sus1 or Sus2, whereas feeding metabolizable sugars (sucrose or glucose) or non-metabolizable osmotica [poly(ethylene glycol), sorbitol or mannitol] mimicked the effects of osmotic stress on Sus1 expression in detached leaves. By using various sucrose/mannitol solutions, we demonstrated that Sus1 was up-regulated by a decrease in leaf osmotic potential rather than an increase in sucrose concentration itself. We suggest that Sus1 expression is regulated via an ABA-independent signal transduction pathway that is related to the perception of a decrease in leaf osmotic potential during stresses. In contrast, the expression of Sus2 was independent of sugar/osmoticum effects, suggesting the involvement of a signal transduction mechanism distinct from that regulating Sus1 expression. The differential stress-responsive regulation of Sus genes in leaves might represent part of a general cellular response to the allocation of carbohydrates during acclimation processes.
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Claims 9
Claim · model-written summary
Cold and drought increased Sus1 transcripts.
- Taxon
- Arabidopsis
Arabidopsist0 - Treatment
- cold and droughte0
- Gene
- Sus1e0
- Outcome
- Transcript levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transcript levels of Sus1 increased on exposure to cold and drought”
t0“Arabidopsis”
Claim · model-written summary
Oxygen deficiency induced Sus2 mRNA.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sus2 mRNA was induced specifically by O2 deficiency”
t0“Arabidopsis”
Claim · model-written summary
Cold and drought induced soluble sugar accumulation.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- cold and drought exposurese0
- Outcome
- accumulation of soluble sugarse0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both cold and drought exposures induced the accumulation of soluble sugars”
t0“Arabidopsis”
Claim · model-written summary
Cold and drought decreased leaf osmotic potential.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- cold and drought exposurese0
- Outcome
- leaf osmotic potentiale0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cold and drought exposures induced the accumulation of soluble sugars and caused a decrease in leaf osmotic potential”
t0“Arabidopsis”
Claim · model-written summary
Oxygen deficiency nearly depleted sugars.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- O2 deficiencye0
- Outcome
- sugarse0
- Direction
- depletione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“O2 deficiency was characterized by a nearly complete depletion in sugars”
t0“Arabidopsis”
Claim · model-written summary
ABA feeding and ABA deficiency did not alter Sus expression profiles.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- Feeding abscisic acid (ABA)e0
- Outcome
- expression profiles of Sus1 or Sus2e0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Feeding abscisic acid (ABA) to detached leaves or subjecting Arabidopsis ABA-deficient mutants to cold stress conditions had no effect on the expression profiles of Sus1 or Sus2”
t0“Arabidopsis”
Claim · model-written summary
Sugars and osmotica mimicked osmotic stress effects on Sus1.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- metabolizable sugars (sucrose or glucose)e0
- Gene
- Sus1e0
- Outcome
- Sus1 expressione0
- Direction
- mimickede0
- Comparator
- osmotic stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“feeding metabolizable sugars (sucrose or glucose) or non-metabolizable osmotica [poly(ethylene glycol), sorbitol or mannitol] mimicked the effects of osmotic stress on Sus1 expression in detached leaves”
t0“Arabidopsis”
Claim · model-written summary
Reduced leaf osmotic potential upregulated Sus1 rather than sucrose concentration.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sus1 was up-regulated by a decrease in leaf osmotic potential rather than an increase in sucrose concentration itself”
t0“Arabidopsis”
Claim · model-written summary
Sus2 expression was independent of sugar and osmotic effects.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- sugar/osmoticum effectse0
- Gene
- Sus2e0
- Outcome
- expression of Sus2e0
- Direction
- independente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the expression of Sus2 was independent of sugar/osmoticum effects”
t0“Arabidopsis”
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