Genome-Wide Identification of the SMXL Gene Family in Common Wheat and Expression Analysis of TaSMXLs Under Abiotic Stress

Strigolactones (SLs), a novel class of plant hormones, play a crucial role in plant growth and development. SMXL (SUPPRESSOR OF MAX2 1-like) is a key gene in the SL signaling pathway, regulating its function by inhibiting the reception of SL signals. Therefore, investigating how SMXL regulates SL to influence wheat growth, development, and stress resistance is of significant importance. In this study, 22 SMXL genes were identified in the Chinese Spring wheat reference genome. Bioinformatics analysis revealed that these genes belong to the Group II subfamily, exhibiting similar physicochemical properties and conserved motifs. Ka/Ks analysis indicated that these genes have undergone purifying selection during evolution. Cis-acting element analysis showed that the promoter regions of TaSMXL genes are enriched with light-responsive elements and regulatory elements related to growth, development, and stress responses. Expression pattern analysis demonstrated that TaSMXL genes exhibit significant differential expression under drought, salt, and cold stress conditions, revealing the potential molecular mechanisms of wheat’s response to multiple abiotic stresses. This study provides a theoretical foundation for understanding the functional roles of SMXL genes in wheat and offers valuable candidate gene resources for breeding stress-resistant wheat varieties.