Genome-wide identification of SCL gene family in potato (Solanum tuberosum L.) and expression analyses under phytohormones, drought and salt stress

Abiotic stresses, such as drought and salinity, severely limit the yield and quality of potato. As a pivotal subfamily of GRAS transcription factors, SCARECROW-like (SCL) proteins play essential roles in phytohormone signaling and stress adaptation; however, their systematic characterization and functional mechanisms in potato remain largely unexplored. In this study, we conducted a genome-wide identification of the SCL gene family and identified 71 StSCL genes in potato. Phylogenetic analysis revealed that potato StSCL proteins share the closest evolutionary relationship with their counterparts in tomato. Structural and promoter analyses showed that StSCL members contain conserved GRAS and DELLA domains and harbor abundant cis -acting elements responsive to ABA, SA, JA, GA, and diverse abiotic stresses. Protein-protein interaction (PPI) network analysis predicted StSCL13, StSCL24, and StSCL66 as potential hub genes. Expression profiling revealed obvious tissue-specific expression patterns and widespread responses to phytohormone and stress treatments. StSCL3 was selected for further functional characterization due to its intact and conserved GRAS domain, as well as the proven hormonal and pathogen-responsive functions of its homolog in our previous study. Subcellular localization assay indicated that StSCL3 is a nuclear-localized protein. Its expression was significantly induced by ABA, GA, SA, JA, and drought stress but repressed by salt stress. Such divergent expression responses indicate that StSCL3 may act as a critical signal integrator that coordinates multiple phytohormone pathways to regulate plant growth and stress adaptation. Collectively, this study elucidates the evolutionary characteristics and regulatory mechanisms of the potato SCL family, highlighting the pivotal role of StSCL3 in hormone signaling and abiotic stress responses, and providing a theoretical foundation for improving stress resistance in potato.