The salt and ABA inducible transcription factor gene, SlAITR3, negatively regulates tomato salt tolerance

It was of great significance for genetic improvement of salt-tolerant crops and increasing the yield of saline-alkali land to excavate salt stress response genes and clarify their molecular mechanism of regulating salt tolerance. Plant-specific transcription factor (TF) ABA-induced transcription repressors (AITRs) played important roles in salt stress. Nevertheless, the underlying mechanisms of how tomato AITRs (SlAITRs) regulate salt stress remain to be elucidated. In this study, we systematically described the characteristics of tomato SlAITR3 and its function in regulating salt tolerance. SlAITR3 was a transcriptional repressor located in nucleus, and SlAITR3 gene was induced by salt stress and abscisic acid (ABA). Tomato SlAITR3 silencing and knockout improved the salt tolerance. Compared with wide-type (WT) plants, the Na⁺/K⁺ ratio, cell membrane permeability and reactive oxygen species (ROS) were lower in SlAITR3 silencing or knockout mutants under salt stress conditions, while the antioxidant enzyme activities were higher. Conversely, the SlAITR3-overexpressing tomato plants showed sensitivity to salt stress. RNA-seq analysis suggested that SlAITR3 might function by regulating stress response genes, especially key genes involved in ion homeostasis and ROS metabolism. In summary, the nuclear localization TF SlAITR3 protein negatively regulated tomato salt tolerance. Our results provided a potential target and a new theoretical reference for the genetic improvement of tomato salt tolerance by biotechnology.