Genome-wide identification and expression analysis of SLAC1 gene family in tomato (Solanum lycopersicum) and the function of SlSLAC1–6 under cold stress

The effects of cold stress on plants are mainly reflected in enzyme activity, membrane system, cell water loss, etc., leading to cell metabolism disorder, and even death. The SLAC1 gene family encodes S-type anionic channel proteins, which play an essential role in plant response to environmental stimuli by regulating stomatal opening and closure of guard cells. Therefore, the tomato SLAC1 gene family was used as the object of this study to explore its function and mechanism in tomato cold resistance. Firstly, bioinformatics analysis showed that most of the promoter regions of the SLAC1 gene family members contained stress-related cis-acting elements. Transcriptomic data and qRT-PCR experiments result show that SlSLAC1–6 might be a key gene in the resistance of the family. After cold treatment, the increase of antioxidant enzymes in SLAC1–6 silenced plants resulted in the inability of plants to maintain normal osmotic pressure of cells and significantly reduced the cold tolerance of tomato plants compared with the control (pTRV2:00) tomato plants. In addition, the stomatal aperture of the SLAC1–6 silenced plant was significantly more extensive than that of the pTRV2:00 tomato plants. The results showed that SlSLAC1–6 was a positive regulator of tomato cold resistance. In conclusion, our study provides a more extensive analysis of the tomato SLAC1 gene family and will provide a reference for future research on the mechanism of the SlSLAC1–6 gene in tomato cold resistance.