AUTHOR=Kim Young-Saeng , Kim Jin-Ju , Park Seong-Im , Diamond Spencer , Boyd Joseph S. , Taton Arnaud , Kim Il-Sup , Golden James W. , Yoon Ho-Sung 

TITLE=Expression of OsTPX Gene Improves Cellular Redox Homeostasis and Photosynthesis Efficiency in Synechococcus elongatus PCC 7942

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01848

DOI=10.3389/fpls.2018.01848

ISSN=1664-462X

ABSTRACT=<p>Cyanobacterial 2-Cys peroxiredoxin (thioredoxin peroxidase, <italic>TPX</italic>) comprises a family of thiol antioxidant enzymes critically involved in cell survival under oxidative stress. In our previous study, a putative <italic>TPX</italic> was identified using a proteomics analysis of rice (<italic>Oryza sativa</italic> L. <italic>japonica</italic>, <italic>OsTPX</italic>) seedlings exposed to oxidative stress. This <italic>OsTPX</italic> gene is structurally similar to the <italic>Synechococcus elongatus TPX</italic> gene in the highly conserved redox-active disulfide bridge (Cys114, Cys236) and other highly conserved regions. In the present study, the <italic>OsTPX</italic> gene was cloned into rice plants and <italic>S. elongatus</italic> PCC 7942 strain to study hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) stress responses. The <italic>OsTPX</italic> gene expression was confirmed using semi-quantitative RT-PCR and western blot analysis. The <italic>OsTPX</italic> gene expression increased growth under oxidative stress by decreasing reactive oxygen species and malondialdehyde level. Additionally, the <italic>OsTPX</italic> gene expression in <italic>S. elongatus</italic> PCC 7942 (OT) strain exhibited a reduced loss of chlorophyll and enhanced photosynthesis efficiency under H<sub>2</sub>O<sub>2</sub> stress, thereby increasing biomass yields twofold compared with that of the control wild type (WT) strain. Furthermore, redox balance, ion homeostasis, molecular chaperone, and photosynthetic systems showed upregulation of some genes in the OT strain than in the WT strain by RNA-Seq analysis. Thus, <italic>OsTPX</italic> gene expression enhances oxidative stress tolerance by increasing cell defense regulatory networks through the cellular redox homeostasis in the rice plants and <italic>S. elongatus</italic> PCC 7942.</p>