Genome-Wide Identification and Salt Tolerance Analysis of the SKS Gene Family in Soybean

The Skewed5 Similar (SKS) genes play a crucial role in plant growth and development, as well as in responding to abiotic stress, by regulating cell wall remodeling and maintaining reactive oxygen species (ROS) homeostasis. The SKS gene family has not yet been thoroughly studied in soybean. We conducted a comprehensive genome-wide analysis of 88 GmSKS genes, systematically elucidating their gene structures, conserved protein domains, collinearity relationships, and phylogenetic relationships, to identify potential candidate genes associated with soybean tolerance to salt stress. The GmSKS genes are distributed across 18 chromosomes, and the expansion of this gene family is primarily attributed to the combined effects of tandem duplications and segmental duplications. Different tissue-specific expression patterns among GmSKS members were identified using expression profiling. Analysis of cis-regulatory elements further revealed that the promoter region may be involved in plant hormone signaling pathways and responses to abiotic stress. Furthermore, quantitative reverse transcription PCR (qRT-PCR) analysis showed that 21 of the 22 examined GmSKS genes were significantly upregulated under salt stress, while one was significantly downregulated. This expression pattern may be linked to salt tolerance mechanisms in soybean under stress conditions. Haplotype and selection trend analyses of GmSKSs revealed that varieties carrying GmSKS5^1123G, GmSKS22^1727G, GmSKS43^50T and GmSKS71^1213T are highly enriched in cultivated soybeans and have undergone artificial selection. This study provides basic information for the identification of salt stress-responsive gene resources of GmSKS family genes, and provides novel theoretical insights for the functional identification and cloning of soybean salt tolerance-related genes.