Abstract
Abscisic acid (ABA) and calcium respectively work as crucial plant hormones and second signalling molecules in the regulation of fruit development and quality formation, including the sugar content and flavour quality. However, the regulatory mechanisms of fruit sugar accumulation arising from the interaction between ABA and calcium have not yet been fully elucidated. Here, we show that the application of ABA or calcium enhances sugar accumulation in sweet orange (Citrus sinensis) fruit, accompanied by upregulation of the expression level of tonoplast sugar transporter 2 (CsTST2), which mediates the transport of sugars into the vacuole. Based on molecular and transgenic analyses, we identified CsABI5 as the core transcription factor that positively regulates CsTST2 expression for sugar accumulation. Both CsSRK2A, a key player in ABA signalling, and CsCIPK6, a kinase linked to calcium signalling, interact with and phosphorylate CsABI5 at distinct amino acid sites to enhance its transcriptional activity. Interestingly, CsABI5 also activates the expression of CsCIPK6 by binding to its promoter, thereby establishing a positive feedback loop between ABA and calcium signalling that cascades into higher expression of CsTST2 and sugar content. Collectively, these findings uncover a novel molecular network that underlies sugar accumulation in citrus, revealing the intricate coordination between ABA and calcium signalling in regulating tonoplast sugar transport in a non-climacteric fruit.
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Claims 8
Claim · model-written summary
ABA application enhanced sugar accumulation in sweet orange fruit.
- Taxon
- sweet orange
Citrus sinensise1 - Treatment
- application of ABAe1
- Outcome
- sugar accumulatione1
- Direction
- enhancese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the application of ABA or calcium enhances sugar accumulation in sweet orange (Citrus sinensis) fruit”
Claim · model-written summary
Calcium application enhanced sugar accumulation in sweet orange fruit.
- Taxon
- sweet orangeCitrus sinensise1
- Treatment
- calciume1
- Outcome
- sugar accumulatione1
- Direction
- enhancese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the application of ABA or calcium enhances sugar accumulation in sweet orange (Citrus sinensis) fruit”
Claim · model-written summary
ABA application was accompanied by upregulated expression of CsTST2 in sweet orange fruit.
- Taxon
- sweet orangeCitrus sinensise1
- Treatment
- application of ABAe1
- Gene
- CsTST2e1
- Outcome
- expression level of tonoplast sugar transporter 2e1
- Direction
- upregulatione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the application of ABA or calcium enhances sugar accumulation in sweet orange (Citrus sinensis) fruit, accompanied by upregulation of the expression level of tonoplast sugar transporter 2 (CsTST2)”
Claim · model-written summary
Calcium application was accompanied by upregulated expression of CsTST2 in sweet orange fruit.
- Taxon
- sweet orangeCitrus sinensise1
- Treatment
- calciume1
- Gene
- CsTST2e1
- Outcome
- expression level of tonoplast sugar transporter 2e1
- Direction
- upregulatione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the application of ABA or calcium enhances sugar accumulation in sweet orange (Citrus sinensis) fruit, accompanied by upregulation of the expression level of tonoplast sugar transporter 2 (CsTST2)”
Claim · model-written summary
CsABI5 is the core transcription factor that positively regulates CsTST2 expression for sugar accumulation in citrus.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“we identified CsABI5 as the core transcription factor that positively regulates CsTST2 expression for sugar accumulation”
t0“Citrus”
Claim · model-written summary
CsSRK2A interacts with and phosphorylates CsABI5 at a distinct amino acid site to enhance its transcriptional activity.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Both CsSRK2A, a key player in ABA signalling, and CsCIPK6, a kinase linked to calcium signalling, interact with and phosphorylate CsABI5 at distinct amino acid sites to enhance its transcriptional activity”
t0“Citrus”
Claim · model-written summary
CsCIPK6 interacts with and phosphorylates CsABI5 at a distinct amino acid site to enhance its transcriptional activity.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Both CsSRK2A, a key player in ABA signalling, and CsCIPK6, a kinase linked to calcium signalling, interact with and phosphorylate CsABI5 at distinct amino acid sites to enhance its transcriptional activity”
t0“Citrus”
Claim · model-written summary
CsABI5 activates the expression of CsCIPK6 by binding to its promoter, forming a positive feedback loop between ABA and calcium signalling.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“CsABI5 also activates the expression of CsCIPK6 by binding to its promoter”
t0“Citrus”
The same questions in other papers
(+)-abscisic acid · molecular: metabolites · Citrus sinensis (sweet orange)Positive and negative results
1 in the opposite direction
- no effect
calcium atom · molecular: metabolites · Citrus sinensis (sweet orange)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
2 papers more in this group
See all 6 papers →(+)-abscisic acid · molecular: expression · Citrus sinensis (sweet orange)Results agree
1 paper in the same direction as this paper
- positive
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.