Elucidating the role of brassinosteroid signaling genes and their promoters in Arabidopsis revealed regulatory mechanisms in plant development and responses to different abiotic stresses.

Brassinosteroids (BRs) are essential plant steroid phytohormones that regulate a wide range of developmental processes and mediate plant responses to various biotic and abiotic stresses. BR signaling regulators have significant potential to optimize plant architecture and enhance resilience to environmental stress. Although the BR signaling pathway is well-characterized in the dicot model species Arabidopsis (Arabidopsis thaliana), our knowledge of this pathway at the transcriptional level remains limited and requires further investigation. Moreover, the functional roles of several other conserved genes involved in the BR signaling pathway in Arabidopsis are not yet fully understood. Therefore, the present study was designed to conduct detailed and comprehensive analysis of BR signaling genes, promoter regions, and their encoded proteins in Arabidopsis. A bibliometric approach was used to compile a list of potential BR-signalling genes. A total of 41 BR signaling genes and their promoter sequences were selected for comprehensive silico analyses, including gene structure visualization, characterization, phylogenetic evolution, identification of cis-regulatory elements, and prediction of different transcription factor binding sites (TFbs) within 1.5 kb upstream of the promoter sequences in Arabidopsis. The expression patterns of these 41 BR signaling genes were examined in various plant organs and under different abiotic and hormonal stress conditions. Quantitative PCR (qPCR) was performed to validate the expression profiles of several BR signaling genes under osmotic stress (polyethylene glycol (PEG)-induced) and salt stress. In addition, protein-protein interactions (PPI) encoded by BR signaling genes were predicted in Arabidopsis. These analyses identified different types and frequencies of cis-elements and TFbs associated with plant growth and stress responses. Overall, this study provides valuable insights into the regulatory mechanisms underlying the coordinated expression of BR signaling genes in Arabidopsis, with potential implications for both monocots and dicots.