Abstract
BACKGROUND: Soil salinization can lead to reduced soil activity, damage to the plant root system, stunted crop growth and reduced yield. Foxtail millet, an important cereal crop, has high nutritional and economic value but is affected by salt stress during growth. During long-term evolution, foxtail millet has developed various regulatory mechanisms to cope with salt stress. Among them, the glutathione S-transferase (GST) gene family plays a key role in the response to salt stress. GSTs are superfamily enzymes encoded by multiple genes with multiple functions that increase plant resistance to abiotic stresses through antioxidant defence and detoxification processes. RESULTS: We identified the gene SiGSTU24, which was the most highly upregulated gene under salt stress among the foxtail millet GST gene family, via screening. We found that, compared with WT and atgstu24 plants, Arabidopsis overexpressing SiGSTU24 presented a greater germination rate and taller plant height after salt stress. Moreover, we found that SiGSTU24 reduced ROS accumulation and changed the activities of antioxidant defence system enzymes in Arabidopsis. SiGSTU24 increased the expression of the antioxidant enzyme-related genes ascorbate peroxidase (AtAPX), superoxide dismutase (AtSOD), peroxidase (AtPOD), and catalase (AtCAT) in Arabidopsis. RNA-Seq and qRT‒PCR verification revealed that SiGSTU24 enhanced salt tolerance and antioxidant capacity in Arabidopsis under salt stress by regulating antioxidant enzyme-related genes and transcription factors. These genes and transcription factors may help Arabidopsis adapt to salt stress environments through various biochemical pathways and regulatory networks. CONCLUSIONS: SiGSTU24 overexpression enhances salt stress tolerance in Arabidopsis. This research provides a foundation for the study of SiGSTU24 function and supplements studies on gene functions in the foxtail millet GST gene family.