The SlDUF789 Gene Family in Tomato: Genome-Wide Identification and Responsiveness to Hormonal and Abiotic Stress Signals

The DUF789 protein family comprises conserved domain proteins in plants, most of which remain functionally uncharacterized despite their involvement in growth, development, and stress responses. Moreover, systematic identification of the DUF789 family in tomato (Solanum lycopersicum L.) has not been reported. In this study, 11 SlDUF789 members were identified from the tomato genome, unevenly distributed across seven chromosomes, with members within the same subgroup sharing similar exon–intron structures and conserved motifs. Promoter analysis revealed the enrichment of cis-acting elements associated with light, hormone, and stress responses. Quantitative real-time PCR (qRT-PCR) analysis revealed diverse expression patterns across tissues: most SlDUF789 members exhibited relatively high expression levels in reproductive tissues, whereas SlDUF789-7 was broadly expressed across all tissues, with elevated expression in fully open flowers and red-ripe fruits. Under stress and hormone treatments, SlDUF789-7 exhibited the highest induction under ABA and salt stress; SlDUF789-8 under MeJA and PEG; and SlDUF789-11 under SA and low-light. Notably, SlDUF789-7 responded strongly across all treatments, whereas SlDUF789-11 showed sustained upregulation under low-light stress. This study provides the first systematic characterization of the SlDUF789 gene family in tomato and establishes a foundation for future research on their biological functions and potential roles in stress responses.