Genome-Wide Identification of the Phytocyanin Gene Family and Its Potential Function in Salt Stress in Soybean (Glycine max (L.) Merr.)

Phytocyanins (PCs), plant-specific blue copper proteins, are crucial for various biological processes during plant development. However, a comprehensive characterization of the soybean PC gene family (GmPC) is lacking. In this study, we performed genome-wide screening of soybean PC genes, and 90 PC genes were identified in the soybean genome. Further analysis revealed that the GmPC family was categorized into four subfamilies (stellacyanins, GmSCs; uclacyanins, GmUCs; plantacyanins, GmPLCs; and early nodulin-like proteins, GmENODLs). In-depth analysis revealed that each specific GmPC subfamily exhibited similar characteristics, with segmental duplications playing a major role in expanding the members of GmPC. Additionally, synteny and evolutionary constraint analyses suggested that GmPCs have undergone strong selective pressure for purification during the evolution of soybeans. The promoter cis-regulatory elements analysis of GmPCs suggested that GmPCs might play a crucial role in various stress responses. The expression patterns of GmPCs exhibited tissue-specific variations. Moreover, 23 of the GmPCs may be involved in soybean's response to salt stress. In all, our study presents a systematic overview of GmPC, which not only provides a valuable foundation for further functional investigations of GmPCs, but also offers new insights into the mechanism of soybean salt tolerance.