Identification of tomato bromodomain-containing genes and functional characterization of SlGTE7 in drought and salt stresses

The bromodomain is a crucial protein structural module responsible for specifically recognizing and binding acetylated lysine residues on histone tails. This recognition capability plays a pivotal role in epigenetic regulation, extensively influencing cellular processes. While bromodomain-containing proteins have been characterized in species such as Arabidopsis, rice, and wheat, their presence and function in tomato remain underexplored. In this study, we identified 22 bromodomain-containing genes in tomato, including 9 SlGTE genes, 11 SlBRD genes, one SlHAG1 gene, and one SlCHR2 gene. Phylogenetic analysis categorized these genes into seven distinct groups. Gene duplication analysis indicated that whole-genome duplication or segmental duplication events are the primary mechanisms driving the expansion of the tomato bromodomain gene family, with these genes being subjected to purifying selection. Under stress conditions, SlGTE7 was significantly induced by drought, salt, and abscisic acid. Silencing SlGTE7 resulted in reduced tolerance to drought and salt stresses in tomato plants. This study provides a comprehensive identification of bromodomain genes in tomato, enhances our understanding of this gene family, and lays a theoretical foundation for molecular breeding aimed at improving drought and salt tolerance in tomato.