Literature summary for 1.8.5.1 extracted from

Terai, Y.; Ueno, H.; Ogawa, T.; Sawa, Y.; Miyagi, A.; Kawai-Yamada, M.; Ishikawa, T.; Maruta, T.
Dehydroascorbate reductases and glutathione set a threshold for high-light-induced ascorbate accumulation (2020), Plant Physiol., 183, 112-122 .

Cloned(Commentary)

Cloned (Comment)	Organism
production of a triple mutant lacking all three DHARs, dhar1, dhar2, and dhar3, are crossed with each other, resulting in the generation of double mutants dhar1/dhar2, dhar1/dhar3, and dhar2/dhar3. Among these double mutants, dhar1/dhar3 and dhar2/dhar3 are further crossed with each other to generate the triple-knockout mutant dhar1/dhar2/dhar3 (termed DELTAdhar), which is isolated from the F2 population by using PCR-based genotyping	Arabidopsis thaliana

Cloned (Comment)

Organism

production of a triple mutant lacking all three DHARs, dhar1, dhar2, and dhar3, are crossed with each other, resulting in the generation of double mutants dhar1/dhar2, dhar1/dhar3, and dhar2/dhar3. Among these double mutants, dhar1/dhar3 and dhar2/dhar3 are further crossed with each other to generate the triple-knockout mutant dhar1/dhar2/dhar3 (termed DELTAdhar), which is isolated from the F2 population by using PCR-based genotyping

Arabidopsis thaliana

Protein Variants

Protein Variants	Comment	Organism
additional information	generation of DELTAdhar Arabidopsis plants as well as a quadruple mutant line combining DELTAdhar with an additional vtc2 mutation that causes ascorbate deficiency. Measurements of ascorbate in these mutants under low- or high-light conditions indicate that DHARs have a nonnegligible impact on full ascorbate accumulation under high light, but that they are dispensable when ascorbate concentrations are low to moderate. Because GSH itself can reduce DHA nonenzymatically, the pad2 mutant is used that contains about 30% of the wild-type GSH level. The pad2 mutant accumulates ascorbate at a wild-type level under high light, but when the pad2 mutation is combined with DELTAdhar, there is near-complete inhibition of high-light-dependent ascorbate accumulation. The lack of ascorbate accumulation is consistent with a marked increase in the ascorbate degradation product threonate. These findings indicate that ascorbate recycling capacity is limited in DELTAdhar pad2 plants, and that both DHAR activity and GSH content set a threshold for high-light-induced ascorbate accumulation. Each gene knockout is confirmed by reverse transcription PCR. The measurement of DHAR activity reveals that DHAR1 and DHAR3 are the major isoforms, and that the triple DELTAdhar mutant has negligible DHAR activity. DHAR loss-of-function does not affect MDAR activity	Arabidopsis thaliana

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
chloroplast	-	Arabidopsis thaliana	9507	-
cytosol	-	Arabidopsis thaliana	5829	-
peroxisome	-	Arabidopsis thaliana	5777	-

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
2 glutathione + dehydroascorbate	Arabidopsis thaliana	-	glutathione disulfide + ascorbate	-	?
2 glutathione + dehydroascorbate	Arabidopsis thaliana Col-0	-	glutathione disulfide + ascorbate	-	?

Organism

Organism	UniProt	Comment	Textmining
Arabidopsis thaliana	Q8LE52	-	-
Arabidopsis thaliana	Q9FRL8	-	-
Arabidopsis thaliana	Q9FWR4	-	-
Arabidopsis thaliana Col-0	Q8LE52	-	-
Arabidopsis thaliana Col-0	Q9FRL8	-	-
Arabidopsis thaliana Col-0	Q9FWR4	-	-

Source Tissue

Source Tissue	Comment	Organism	Textmining
leaf	-	Arabidopsis thaliana	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
2 glutathione + dehydroascorbate	-	Arabidopsis thaliana	glutathione disulfide + ascorbate	-	?
2 glutathione + dehydroascorbate	-	Arabidopsis thaliana Col-0	glutathione disulfide + ascorbate	-	?

Synonyms

Synonyms	Comment	Organism
At1g19570	locus name	Arabidopsis thaliana
At1g75270	locus name	Arabidopsis thaliana
At5g16710	locus name	Arabidopsis thaliana
AtDHAR1	-	Arabidopsis thaliana
AtDHAR2	-	Arabidopsis thaliana
AtDHAR3	-	Arabidopsis thaliana
dehydroascorbate reductase	-	Arabidopsis thaliana
DHA reductase	-	Arabidopsis thaliana
DHAR	-	Arabidopsis thaliana

Temperature Optimum [°C]

Temperature Optimum [°C]	Temperature Optimum Maximum [°C]	Comment	Organism
22	-	assay at room temperature	Arabidopsis thaliana

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7	-	assay at	Arabidopsis thaliana

General Information

General Information	Comment	Organism
physiological function	the DHA reductases (DHARs) that catalyze the GSH-dependent DHA reduction allows plants to rapidly recycle ascorbate from DHA. Cooperation of DHARs and GSH is required for ascorbate accumulation under high-light stress in Arabidopsis thaliana	Arabidopsis thaliana