Soil Salinization: Transcriptomic Insights into Salt Tolerance Mechanisms in Rice

Soil salinization has become a critical factor threatening global crop productivity. Breeding novel salt-tolerant varieties is one of the most economical and efficient strategies to enhance productivity in saline-alkali lands. In the previous study, we observed that salt severely restrain tillering in rice. In this study, to dissect the molecular mechanism underlying salt stress on rice tillering, transcriptome sequencing was conducted using tillering buds at seedling stage of salt-tolerant rice cultivar Nipponbare (Nip) and salt-susceptible cultivar Kongyu 131 (KY131) being treated with or without salinity. The results demonstrated that Nip plants exhibited superior adaptability to high-salinity conditions: after transient changes at transcriptional levels, most genes reverted to their baseline expression levels within 24 hours after salt treatment. In contrast, KY131 plants displayed progressively intensified gene expression alterations as treatment duration extended. Functional annotation of differentially expressed genes (DEGs) revealed that genes involved in some metabolic pathways, including phenylpropanoid metabolism, chlorophyll biosynthesis, nitrogen metabolism, and phytohormone signaling may play pivotal roles in enhancing salt tolerance. In addition, it was found that a list of DEGs were key regulators of rice tillering. Co-expression analysis identified a NAC transcription factor, OsNAC4, as a central hub in salt stress signaling. Further experiment demonstrated that OsNAC4 negatively regulates rice salt tolerance and tillering. These findings established a molecular link between rice responses to high salinity and tillering, and provide valuable genetic resources for breeding salt-tolerant rice cultivars.