H2S regulates low oxygen signaling via integration with the unfolded protein response in Arabidopsis thaliana

Purpose Hydrogen sulfide (H2S) is an important signaling molecule in prokaryotes and eukaryotes. In higher plants, H2S regulates different processes throughout development and stress responses. Here, we investigated the underlying mechanism of H2S in modulating hypoxia response signaling in Arabidopsis. Methods DAB (3,3-diaminobenzidine) and fluorescent probes were used to detect the accumulation of reactive oxygen species and H2S. Evans blue staining was conducted to observe the cell death. Quantitative RT-PCR was performed to measure the relative gene expression levels. Results Our data showed that endogenous H2S production was induced by anoxia and appropriate application of exogenous H2S mitigated the damage caused by submergence stress. Meanwhile, the histological staining, fluorescent microscope observation and molecular analysis demonstrated that H2S metabolism-related mutants oasa1 and lcddes1-1 accumulated different ROS levels and exhibited different low oxygen sensitivities compared with the wild type. In addition, we observed that ER stress response genes were up-regulated in wild type upon anoxia, and different ER stress response-related mutants ero1-2, ero1-3, ero2-1, ero2-2 and bzip28bzip60 were more sensitive to submergence or anoxia than wild type. Moreover, the exogenous H2S pretreatment could not alleviate submergence-induced leaf death in ero2-1 compared with wild type, indicating that hypoxia induced ER stress and activation of the unfolded protein response (UPR) signal pathway is important for plant hypoxia response. Conclusion Our work demonstrates that H2S regulates hypoxic stress response through the integration with UPR. This study provides new insights into H2S function during plant low oxygen stress response.