Expression of Gene Improves Cellular Redox Homeostasis and Photosynthesis Efficiency in PCC 7942.

Cyanobacterial 2-Cys peroxiredoxin (thioredoxin peroxidase, ) comprises a family of thiol antioxidant enzymes critically involved in cell survival under oxidative stress. In our previous study, a putative was identified using a proteomics analysis of rice ( L. , ) seedlings exposed to oxidative stress. This gene is structurally similar to the gene in the highly conserved redox-active disulfide bridge (Cys114, Cys236) and other highly conserved regions. In the present study, the gene was cloned into rice plants and PCC 7942 strain to study hydrogen peroxide (HO) stress responses. The gene expression was confirmed using semi-quantitative RT-PCR and western blot analysis. The gene expression increased growth under oxidative stress by decreasing reactive oxygen species and malondialdehyde level. Additionally, the gene expression in PCC 7942 (OT) strain exhibited a reduced loss of chlorophyll and enhanced photosynthesis efficiency under HO 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, gene expression enhances oxidative stress tolerance by increasing cell defense regulatory networks through the cellular redox homeostasis in the rice plants and PCC 7942.