Genome-Wide Analysis of AGC Genes Related to Salt Stress in Soybeans (Glycine max)

The AGC protein kinase family plays a crucial role in regulating plant growth, immunity, and cell death, as well as responses to abiotic stresses such as salt-induced stress, which impact plant development and productivity. While the functions of AGC kinases have been thoroughly studied in model plants such as <i>Arabidopsis thaliana</i>, their roles in soybeans (<i>Glycine max</i>) remain poorly understood. In this study, we identified 69 <i>AGC</i> kinase genes in soybeans, which are unevenly distributed across 19 chromosomes and classified into five subfamilies: PDK1, AGCVI, AGCVII, AGCVIII, and AGC (other). Each subfamily shares similar exon-intron structures and specific motifs. Gene duplication and selection pressure analyses revealed that the <i>GmAGC</i> gene family is primarily expanded through segmental or whole-genome duplication, with all genes undergoing purifying selection during evolution. Promoter analysis identified numerous <i>cis</i>-regulatory elements associated with light, hormonal, and abiotic stress responses, including salt stress. The gene expression analysis demonstrated tissue-specific patterns, with the highest expression levels found in roots (19.7%). Among the 54 <i>GmAGC</i> genes analyzed using RT-qPCR, significant changes in expression were observed in the roots and leaves treated with sodium chloride, with most genes showing increased expression. These results illustrate the critical role of the soybean <i>AGC</i> kinase gene family in regulating responses to salinity stress. Our findings suggest that targeting specific <i>GmAGC</i> genes may enhance soybean resistance to salt toxicity, offering valuable insights for future crop improvement strategies.