Abstract
RelA/SpoT homolog controls the level of guanosine 3', 5'-bispyrophosphate (ppGpp) and guanosine 3'-disphosphate 5'-triphospate (pppGpp), effectors of the stringent response in bacteria. To adapt stress conditions, bacteria accumulate ppGpp, which binds to the RNA polymerase and leading to activation or repression of gene expression. Previously, RelA/SpoT horologes from Arabidopsis thaliana (AtRSH) have been identified. This suggests that the conserved stress-adaptation system may exist in higher plants, but the role of plants RSH is still unknown. Previously, to analyze the mechanism of salt tolerance in a halophyte Suaeda japonica, functional screening was performed using E. coli as a host organism. In this screening, enhanced salt tolerance was observed in E. coli expressing RelA/SpoT homolog (SjRSH). In this study, physiological functions of SjRSH and AtRSH were investigated.
