NtOGG1 regulates tobacco seed germination involving ethylene and reactive oxygen species pathways under salt stress

Abstract

Salt stress significantly inhibits seed germination in tobacco, yet the molecular mechanisms underlying this process remain largely unexplored. In this study, we demonstrated that NtOGG1, encoding an 8-oxoguanine DNA glycosylase, functions as a positive regulator of salt tolerance during seed germination. Under 150 mM NaCl stress, the overexpressing NtOGG1 line (NtOGG1-OE) exhibited higher germination and seedling percentage compared to wildtype (WT), whereas CRISPR–Cas9 knockout mutant showed reductions in both parameters. RNA-Seq analysis revealed that differentially expressed genes (DEGs) in the NtOGG1-OE line, including ethylene-responsive transcription factors (ERFs), respiratory burst oxidase homologs (RBOHs), and catalase (CAT) genes, are implicated in the mitogen-activated protein kinase (MAPK) signaling pathway. Further qRT-PCR and physiological assays confirmed that the enhanced ethylene responses and reduced accumulation of reactive oxygen species (ROS) significantly promote seed germination in the NtOGG1-OE line under salt stress. These findings establish NtOGG1 as a key regulator influencing seed germination under salt stress, providing a promising molecular target for breeding salt-tolerant tobacco cultivars.