Genome-wide identification and evolution of the RCP gene family in soybean uncovers stress-responsive candidates.

Abiotic stress has a significant impact on soybean growth, development, and yield. Proteins containing the Regulator of Chromosome Condensation 1 (RCC1) domain, known as RCPs, play important roles in plant stress responses. However, systematic analysis of the RCP gene family in soybean remains limited. In this study, a total of 52 GmRCP genes were identified in the soybean genome and classified into nine phylogenetic clades. Members within the same clade exhibited similar domain architectures. Collinearity analysis suggested that segmental duplication served as the major driver for the expansion of this gene family, and most duplicated gene pairs underwent purifying selection. Analysis of gene structure and conserved motifs revealed high conservation within clades but divergence among them, indicating potential functional diversification of GmRCPs. Furthermore, promoter analysis identified abundant cis-acting elements associated with hormone signaling and stress responses. Expression profiling demonstrated that most GmRCP genes were expressed across various soybean tissues, and several members were responsive to salt, drought, and low-phosphorus stresses. Notably, GmRCP31, GmRCP43, and GmRCP46 were induced under multiple stresses, suggesting their potential roles in stress adaptation. These findings provide important insights into the functional diversity and evolutionary history of GmRCP genes and establish a foundation for further investigation of their roles in soybean development and stress resistance.