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Literature summary for 1.8.5.1 extracted from
- What are the roles for dehydroascorbate reductases and glutathione in sustaining ascorbate accumulation? (2020), Plant Physiol., 183, 11-12 .
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene DAHR, DHAR overexpression in tobacco plants | Nicotiana benthamiana |
| gene DHAR, DHAR overexpression in maize plants | Zea mays |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | generation of a mutant lacking all three DHAR isozymes (DELTAdhar), the mutant has negligible DHAR activity, but it is shown to be equivalent to wild-type plants in terms of growth and development, as well as ascorbate levels | Arabidopsis thaliana |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| chloroplast | - |
Arabidopsis thaliana | 9507 | - |
| cytosol | - |
Arabidopsis thaliana | 5829 | - |
| mitochondrion | - |
Arabidopsis thaliana | 5739 | - |
| peroxisome | - |
Arabidopsis thaliana | 5777 | - |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 2 glutathione + dehydroascorbate | Nicotiana benthamiana | - |
glutathione disulfide + ascorbate | - |
? |  |
| 2 glutathione + dehydroascorbate | Arabidopsis thaliana | - |
glutathione disulfide + ascorbate | - |
? | |
| 2 glutathione + dehydroascorbate | Zea mays | - |
glutathione disulfide + ascorbate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Arabidopsis thaliana | Q8LE52 | - |
- |
| Arabidopsis thaliana | Q9FRL8 | - |
- |
| Arabidopsis thaliana | Q9FWR4 | - |
- |
| Nicotiana benthamiana | - |
- |
- |
| Zea mays | C0P9V2 | - |
- |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 2 glutathione + dehydroascorbate | - |
Nicotiana benthamiana | glutathione disulfide + ascorbate | - |
? | |
| 2 glutathione + dehydroascorbate | - |
Arabidopsis thaliana | glutathione disulfide + ascorbate | - |
? | |
| 2 glutathione + dehydroascorbate | - |
Zea mays | glutathione disulfide + ascorbate | - |
? | |
| additional information | the activity of DHARs is coupled to oxidation of glutathione, which is also required for spontaneous, nonenzymatic reduction of DHA to ascorbate | Nicotiana benthamiana | ? | - |
- |
|
| additional information | the activity of DHARs is coupled to oxidation of glutathione, which is also required for spontaneous, nonenzymatic reduction of DHA to ascorbate | Arabidopsis thaliana | ? | - |
- |
|
| additional information | the activity of DHARs is coupled to oxidation of glutathione, which is also required for spontaneous, nonenzymatic reduction of DHA to ascorbate | Zea mays | ? | - |
- |
|
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| dehydroascorbate reductase | - |
Nicotiana benthamiana |
| dehydroascorbate reductase | - |
Arabidopsis thaliana |
| dehydroascorbate reductase | - |
Zea mays |
| DHA reductase | - |
Nicotiana benthamiana |
| DHA reductase | - |
Arabidopsis thaliana |
| DHA reductase | - |
Zea mays |
| DHAR | - |
Nicotiana benthamiana |
| DHAR | - |
Arabidopsis thaliana |
| DHAR | - |
Zea mays |
| DHAR1 | - |
Arabidopsis thaliana |
| DHAR1 | - |
Zea mays |
| DHAR2 | - |
Arabidopsis thaliana |
| DHAR3 | - |
Arabidopsis thaliana |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | a mutant lacking all three DHAR isozymes (DELTAdhar), with negligible DHAR activity, is shown to be equivalent to wild-type plants in terms of growth and development, as well as ascorbate levels. Analysis of the DELTAdhar mutant shows that DHARs are required to couple hydrogen peroxide metabolism to glutathione oxidation and that this is functionally important for downstream activation of the salicylic acid pathway. Thus, the role of DHARs in ascorbate recycling remains controversial. DHAR activity is dispensable for growth and ascorbate homeostasis under low light. When subjected to high-light stress, both the wild-type plants and DELTAdhar mutants accumulate ascorbate to high levels, but minor differences are observed after a prolonged stress. The lower ascorbate accumulation of DELTAdhar relative to the wild-type is associated with a slight overaccumulation of threonate, an ascorbate degradation. A blockage of ascorbate accumulation in response to high light is also observed when glutathione deficiency is induced pharmacologically by buthionine sulfoximine treatment, providing extra evidence that, in high-light conditions, glutathione acts as a substitute for ascorbate reduction | Arabidopsis thaliana |
| malfunction | DHAR overexpression in maize leads to an increase in ascorbate and glutathione concentration, as well as a shift toward the reduced state for glutathione | Zea mays |
| malfunction | DHAR-downregulated tobacco lines show reduced total ascorbate levels, lower dry weight, and diminished photosynthetic efficiency. DHAR overexpression in tobacco leads to an increase in ascorbate and glutathione concentration, as well as a shift toward the reduced state for glutathione | Nicotiana benthamiana |
| metabolism | the enzyme is part of the ascorbate recycling pathways, overview | Arabidopsis thaliana |
| physiological function | DHARs are required to couple hydrogen peroxide metabolism to glutathione oxidation and that this is functionally important for downstream activation of the salicylic acid pathway. DHAR activity is dispensable for growth and ascorbate homeostasis under low light | Arabidopsis thaliana |
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