Salt Tolerant Gene 1 contributes to salt tolerance by maintaining photosystem II activity in maize.

Salt stress is a major environmental factor limiting crop growth and productivity. Here, we show that Salt‐Tolerant Gene 1 (ZmSTG1) contributes to salt tolerance by maintaining photosystem activity in maize. ZmSTG1 encodes an endoplasmic reticulum localized protein and retrotransposon insertion in the promoter region causes differential expression levels in maize inbred lines. Overexpression of ZmSTG1 improved plant growth vigor, and knockout of ZmSTG1 weakened plant growth under normal and salt stress conditions. Transcriptome and metabolome analyses indicated that ZmSTG1 might regulate the expression of lipid trafficking‐related genes dependent on the abscisic acid (ABA) signaling pathway, thereby increasing the galactolipids and phospholipid concentrations in the photosynthetic membrane under salt stress. Chlorophyll fluorescence parameters showed that the knockout of ZmSTG1 led to significant impairment of plant photosystem II (PSII) activity under normal and salt stress conditions, whereas overexpression of ZmSTG1 dramatically improved plant PSII activity under salt stress conditions. We also demonstrated that the application of the salt‐tolerant locus could enhance salt tolerance in hybrid maize plants. Taken together, we propose that ZmSTG1 may modulate the lipid composition in the photosynthetic membrane by affecting the expression of lipid trafficking‐related genes to maintain the photosynthetic activity of plants under salt stress. Summary Statement: The identification and use of tolerance genes to alleviate the damage caused by salt stress is an effective strategy for crop genetic improvement. Salt‐Tolerant Gene 1 (ZmSTG1) contributes to salt tolerance by maintaining the photosystem activity in maize. The ZmSTG1‐mediated salt stress response can be achieved by modulating the expression of genes associated with lipid trafficking processes and is dependent on the ABA signaling pathway. [ABSTRACT FROM AUTHOR]