Genome-Wide Identification of GmSPS Gene Family in Soybean and Expression Analysis in Response to Cold Stress

Sucrose metabolism plays a critical role in development, stress response, and yield formation of plants. Sucrose phosphate synthase (SPS) is the key rate-limiting enzyme in the sucrose synthesis pathway. To date, genome-wide survey and comprehensive analysis of the gene family in soybean ( ) have yet to be performed. In this study, seven genes encoding SPS were identified in soybean genome. The structural characteristics, phylogenetics, tissue expression patterns, and cold stress response of these were investigated. A comparative phylogenetic analysis of SPS proteins in soybean, , , , Arabidopsis, and rice revealed four families. GmSPSs were clustered into three families from A to C, and have undergone five segmental duplication events under purifying selection. All genes had various expression patterns in different tissues, and family A members / were highly expressed in nodules. Remarkably, all promoters contain multiple low-temperature-responsive elements such as potential binding sites of inducer of CBF expression 1 (ICE1), the central regulator in cold response. qRT-PCR proved that these genes, especially / , were induced by cold treatment in soybean leaves, and the expression pattern of under cold treatment was similar to that of / . Further transient expression analysis in and electrophoretic mobility shift assay (EMSA) indicated that and transcriptions were directly activated by GmICE1. Taken together, our findings may aid in future efforts to clarify the potential roles of genes in response to cold stress in soybean.