Enhanced ascorbate regeneration via dehydroascorbate reductase confers tolerance to photo-oxidative stress in chlamydomonas reinhardtii

Shu Tseng Lin, Chih Wen Chiou, Yen Lin Chu, Yu Hsiao, Yu Fei Tseng, Yi Chun Chen, Hsien Jung Chen, Hsin Yang Chang, Tse Min Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


The role of ascorbate (AsA) recycling via dehydroascorbate reductase (DHAR) in the tolerance of Chlamydomonas reinhardtii to photo-oxidative stress was examined. The activity of DHAR and the abundance of the CrDHAR1 (Cre10.g456750) transcript increased after moderate light (ML; 750μmol m-2 s-1) or high light (HL; 1,800μmol m-2 s-1) illumination, accompanied by dehydroascorbate (DHA) accumulation, decreased AsA redox state, photo-inhibition, lipid peroxidation, H2O2 overaccumulation, growth inhibition and cell death. It suggests that DHAR and AsA recycling is limiting under high-intensity light stress. The CrDHAR1 gene was cloned and its recombinant CrDHAR1 protein was a monomer (25 kDa) detected by Western blot that exhibits an enzymatic activity of 965 μmol min-1mg-1 protein. CrDHAR1 was overexpressed driven by a HSP70A:RBCS2 fusion promoter or down-regulated by artificial microRNA (amiRNA) to examine whether DHAR-mediated AsA recycling is critical for the tolerance of C. reinahartii cells to photo-oxidative stress. The overexpression of CrDHAR1 increased DHAR protein abundance and enzyme activity, AsA pool size, AsA:DHA ratio and the tolerance to ML-, HL-, methyl viologen- or H2O2-induced oxidative stress. The CrDHAR1-knockdown amiRNA lines that have lower DHAR expression and AsA recycling ability were sensitive to high-intensity illumination and oxidative stress. The glutathione pool size, glutathione:oxidized glutathione ratio and glutathione reductase and ascorbate peroxidase activities were increased in CrDHAR1-overexpressing cells and showed a further increase after high-intensity illumination but decreased in wild-Type cells after light stress. The present results suggest that increasing AsA regeneration via enhanced DHAR activity modulates the ascorbate-glutathione cycle activity in C. reinhardtii against photo-oxidative stress.

Original languageEnglish
Pages (from-to)2104-2121
Number of pages18
JournalPlant and Cell Physiology
Issue number10
StatePublished - Oct 2016


  • Ascorbate
  • Ascorbate-glutathione cycle
  • Chlamydomonas
  • Dehydroascorbate reductase
  • High-intensity light stress


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