Genome-Wide Identification and Expression Analysis of the High-Mobility Group B ( HMGB ) Gene Family in Plant Response to Abiotic Stress in Tomato

High-mobility group B (HMGB) proteins are a class of non-histone proteins associated with eukaryotic chromatin and are known to regulate a variety of biological processes in plants. However, the functions of genes in tomato ( ) remain largely unexplored. Here, we identified 11 members of the family in tomato using BLAST. We employed genome-wide identification, gene structure analysis, domain conservation analysis, -acting element analysis, collinearity analysis, and qRT-PCR-based expression analysis to study these 11 genes. These genes were categorized into four groups based on their unique protein domain structures. Despite their structural diversity, all members contain the HMG-box domain, a characteristic feature of the HMG superfamily. Syntenic analysis suggested that tomato SlHMGBs have close evolutionary relationships with their homologs in other dicots. The promoter regions of are enriched with numerous -elements related to plant growth and development, phytohormone responsiveness, and stress responsiveness. Furthermore, members exhibited distinct tissue-specific expression profiles, suggesting their potential roles in regulating various aspects of plant growth and development. Most genes respond to a variety of abiotic stresses, including salt, drought, heat, and cold. For instance, and showed positive responses to salt, drought, and cold stresses. , , and were involved in responses to two types of stress: responded to drought and heat, while and responded to salt and heat. and were solely regulated by drought and heat stress, respectively. Under various treatment conditions, the number of up-regulated genes significantly outnumbered the down-regulated genes, implying that the family may play a crucial role in mitigating abiotic stress in tomato. These findings lay a foundation for further dissecting the precise roles of genes.