Identification of the SP gene family and transcription factor SlSP5G promotes the high-temperature tolerance of tomatoes.

Some members of the SELF PRUNING (SP) gene family have been shown to play critical roles in developmental processes and stress responses across a wide range of plant species. The study identifies 13 members that can be divided into three subfamilies based on evolutionary analysis. Cis-Acting element analysis of the promoter regions indicated the presence of numerous stress- and hormone-responsive elements in the SlSP family. Subcellular localization analysis showed that the SlSP family proteins are localized in the cell membrane, nucleus, and chloroplasts. Notably, the expression of SELF PRUNING 5G (SlSP5G) was significantly induced by high-temperature stress. Silencing SlSP5G reduced tolerance to high-temperature stress. Conversely, its overexpression in stable transgenic lines enhanced heat tolerance, as demonstrated by improved membrane stability, elevated antioxidant enzyme activity, and reduced reactive oxygen species (ROS) accumulation. In contrast, SlSP5G knockout lines were more susceptible to high-temperature stress. This study provides a comprehensive analysis of the SlSP gene family, offering novel insights into the mechanism of SlSP5G-mediated heat stress tolerance in tomato.