New insights into the evolution analysis of trihelix gene family in eggplant (Solanum melongena L.) and expression analysis under abiotic stress.

Background: Trihliex transcription factors (TFs) play crucial roles in plant growth and development, stress response, and plant hormone signaling network transmission. In order to comprehensively investigate the functions of trihliex genes in eggplant development and the abiotic stress response, we conducted an extensive analysis of the trihliex gene family in the eggplant genome.

Results: In this study, 30 trihelix gene family members were unevenly distributed on 12 chromosomes. On the basis of their phylogenetic relationships, these genes were conserved in different plant species and could be divided into six subfamilies, with trihelix genes within the same subfamily sharing similar structures. The promoter regions of trihelix genes contained cis-acting elements related to plant growth and development, plant hormones, and abiotic stress responses, suggesting potential applications in the development of more resistant crops. Selective pressure assessments indicated that trihliex genes have undergone purifying selection pressure. Expression analysis on the basis of transcriptomic profiles revealed that SmGT18, SmGT29, SmGT6, and SmGT28 are highly expressed in roots, leaves, flowers, and fruits, respectively. Expression analysis via quantitative real-time PCR (qRT‒PCR) revealed that most trihelix genes respond to low temperature, abscisic acid (ABA), and salicylic acid (SA), with SmGT29 exhibiting significant upregulation under cold stress conditions. The SmGT29 gene was subsequently successfully cloned from eggplant, which was located in the nucleus, robust transcriptional activity, and a protein molecular weight of 74.59 kDa. On the basis of these findings, SmGT29 was postulated to be a pivotal candidate gene that actively responds to biotic stress stimuli, thereby supporting the plant's innate stress resistance mechanisms.

Conclusion: In summary, this study was the first report on trihelix genes and their potential roles in eggplant plants. These results provided valuable insights for enhancing stress resistance and quality traits in eggplant breeding, thereby serving as a crucial reference for future improvement efforts.