The purpose of this study was to analyze the evolution, classification and tissue expression specificity of soybean cytosolic glutamine synthetase genes. Glutamine synthetase(GS) proteins from 12 species were downloaded from phytozome database, and used for phylogenetic analysis. The GSs were divided into two groups, cytosolic glutamine synthetase(GS1) and plastidic glutamine synthetase(GS2) based on the maximum likelihood of MEGA 5.10 software. The GS1 group was further divided into five subgroups, includi...