Abstract
The fruit of chestnut rose (Rosa roxburghii Tratt.) contains exceptionally high levels of L-ascorbic acid (AsA) (∼1762 mg/100 g fresh weight), approximately 40-fold higher than those found in sweet orange (Citrus sinensis), which is well known for its high AsA content. However, the molecular mechanisms driving such high accumulation in chestnut rose remain unclear. Here, we report that the genes R. roxburghiiPECTIN METHYLESTERASE (RroxPME), D-GALACTURONATE REDUCTASE (RroxGalUR), and DEHYDROASCORBATE REDUCTASE 2 (RroxDHAR2) play crucial roles in AsA accumulation in chestnut rose fruit. By comparing R. roxburghii with the closely related Rosamultiflora, which has low AsA concentrations, we identified a 545-bp insertion in the promoter of RroxGalUR. We found that TRANSPARENT TESTA GLABRA 2 (RroxTTG2), a well-known key regulator of trichome development, binds to the W-box-containing inserted region of the RroxGalUR promoter as well as the promoters of RroxPME and RroxDHAR2. In contrast, in sweet orange, CsTTG2 can bind only to CsPME. Furthermore, RroxTTG2 retains its conserved role in the regulation of trichome development during early fruit development, suggesting its spatiotemporal specificity in regulating both trichome development and AsA biosynthesis. To evaluate the application value of this pathway in other species, we heterologously expressed RroxTTG2, RroxPME, RroxGalUR, and RroxDHAR2 in lettuce (Lactuca sativa L.), which increased AsA concentrations in the transgenic lines by up to 355% (an increase from approximately 2 to 10 mg/100 g fresh weight). This study provides insights into mechanisms underlying AsA accumulation in chestnut rose and the spatiotemporal transcriptional regulation of AsA biosynthesis and trichome development.
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Claims 7
Claim · model-written summary
Chestnut rose fruit contains about 1762 mg/100 g fresh weight L-ascorbic acid, approximately 40-fold higher than sweet orange.
- Taxon
- chestnut rose
Rosa roxburghiie0 - Organ / stage
- fruite0
- Outcome
- L-ascorbic acid (AsA)e0
- Value
- ∼1762 mg/100 g fresh weighte0
- Qualifier
- approximately 40-fold highere0
- Comparator
- sweet orangee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The fruit of chestnut rose (Rosa roxburghii Tratt.) contains exceptionally high levels of L-ascorbic acid (AsA) (∼1762 mg/100 g fresh weight), approximately 40-fold higher than those found in sweet orange (Citrus sinensis)”
Claim · model-written summary
The genes RroxPME, RroxGalUR and RroxDHAR2 play crucial roles in AsA accumulation in chestnut rose fruit.
- Taxon
- chestnut roseRosa roxburghiie0
- Organ / stage
- fruite0
- Gene
- PECTIN METHYLESTERASE (RroxPME), D-GALACTURONATE REDUCTASE (RroxGalUR), and DEHYDROASCORBATE REDUCTASE 2 (RroxDHAR2)e0
- Outcome
- AsA accumulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PECTIN METHYLESTERASE (RroxPME), D-GALACTURONATE REDUCTASE (RroxGalUR), and DEHYDROASCORBATE REDUCTASE 2 (RroxDHAR2) play crucial roles in AsA accumulation in chestnut rose fruit”
Claim · model-written summary
Compared with the low-AsA Rosa multiflora, R. roxburghii has a 545-bp insertion in the RroxGalUR promoter.
- Taxon
- R. roxburghiiRosa roxburghiie0
- Gene
- RroxGalURe0
- Outcome
- 545-bp insertion in the promotere0
- Value
- 545-bpe0
- Comparator
- Rosamultiflorae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By comparing R. roxburghii with the closely related Rosamultiflora, which has low AsA concentrations, we identified a 545-bp insertion in the promoter of RroxGalUR”
Claim · model-written summary
RroxTTG2 binds the W-box-containing inserted region of the RroxGalUR promoter and the promoters of RroxPME and RroxDHAR2.
- Taxon
- chestnut roseRosa roxburghiie1
- Gene
- RroxTTG2e0
- Outcome
- binds to the W-box-containing inserted region of the RroxGalUR promotere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“TRANSPARENT TESTA GLABRA 2 (RroxTTG2), a well-known key regulator of trichome development, binds to the W-box-containing inserted region of the RroxGalUR promoter as well as the promoters of RroxPME and RroxDHAR2”
e1“The fruit of chestnut rose (Rosa roxburghii Tratt.)”
Claim · model-written summary
In sweet orange, CsTTG2 can bind only to CsPME.
- Taxon
- sweet orange
Citrus sinensise0 - Gene
- CsTTG2e0
- Outcome
- can bind only to CsPMEe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in sweet orange, CsTTG2 can bind only to CsPME”
Claim · model-written summary
RroxTTG2 retains its conserved role in regulating trichome development during early chestnut rose fruit development.
- Taxon
- chestnut roseRosa roxburghiie1
- Organ / stage
- early fruit developmente0
- Gene
- RroxTTG2e0
- Outcome
- regulation of trichome developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“RroxTTG2 retains its conserved role in the regulation of trichome development during early fruit development”
e1“The fruit of chestnut rose (Rosa roxburghii Tratt.)”
Claim · model-written summary
Heterologous expression of RroxTTG2, RroxPME, RroxGalUR and RroxDHAR2 in lettuce increased AsA concentrations in the transgenic lines by up to 355%, from about 2 to 10 mg/100 g fresh weight.
- Taxon
- lettuce
Lactuca sativae0 - Organ / stage
- transgenic linese0
- Treatment
- heterologously expressed RroxTTG2, RroxPME, RroxGalUR, and RroxDHAR2e0
- Outcome
- AsA concentrationse0
- Direction
- increasede0
- Value
- up to 355%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we heterologously expressed RroxTTG2, RroxPME, RroxGalUR, and RroxDHAR2 in lettuce (Lactuca sativa L.), which increased AsA concentrations in the transgenic lines by up to 355% (an increase from approximately 2 to 10 mg/100 g fresh weight)”