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Clade Ib basic helix-loop-helix transcription factor, bHLH101, acts as a regulatory component in photo-oxidative stress responses
- Noshi, Masahiro, Tanabe, Noriaki, Okamoto, Yutaka, Mori, Daisuke, Ohme-Takagi, Masaru, Tamoi, Masahiro, Shigeoka, Shigeru
- Plant science 2018 v.274 pp. 101-108
- Arabidopsis, ascorbate peroxidase, basic helix-loop-helix transcription factors, enzyme activity, gene expression regulation, genes, hydrogen peroxide, iron absorption, knockout mutants, oxidative stress, phenotype, stress response, thylakoids
- The accumulation of reactive oxygen species (ROS) leads to oxidative damage; however, ROS also acts as signaling molecules. We previously demonstrated that the inducible silencing of thylakoid membrane-bound ascorbate peroxidase Arabidopsis plants (IS-tAPX) accumulated H2O2 in their chloroplasts, resulting in the clarification of ROS-responsive genes. In IS-tAPX plants, the transcript levels of the basic helix-loop-helix (bHLH) transcription factor bHLH101, which belongs to clade Ib bHLH, were down-regulated. In order to investigate the participation of bHLH101 in chloroplastic H2O2-mediated signaling, we isolated dominant negative expression mutants of bHLH101 (DN-bHLH101). DN-bHLH101 plants showed a significant phenotype that was sensitive to a methylviologen treatment, even under iron-sufficient conditions. Furthermore, the knock out mutant of bHLH101 showed a photo-oxidative sensitive phenotype, indicating that other clade Ib bHLHs do not compensate for the function of bHLH101. Thus, bHLH101 appears to act as a regulatory component in photo-oxidative stress responses. We also found that ferric chelate reductase activity was stronger in IS-tAPX plants than in control plants, suggesting that there is a close relationship between iron metabolism and oxidative stress responses.