Genome-Wide Analysis and Expression Profiling of Soybean RbcS Family in Response to Plant Hormones and Functional Identification of GmRbcS8 in Soybean Mosaic Virus

Rubisco small subunit (RbcS), a core component with crucial effects on the structure and kinetic properties of the Rubisco enzyme, plays an important role in response to plant growth, development, and various stresses. Although <i>Rbcs</i> genes have been characterized in many plants, their muti-functions in soybeans remain elusive. In this study, a total of 11 <i>GmRbcS</i> genes were identified and subsequently divided into three subgroups based on a phylogenetic relationship. The evolutionary analysis revealed that whole-genome duplication has a profound effect on <i>GmRbcSs</i>. The cis-acting elements responsive to plant hormones, development, and stress-related were widely found in the promoter region. Expression patterns based on the RT-qPCR assay exhibited that <i>GmRbcS</i> genes are expressed in multiple tissues, and notably <i>Glyma.19G046600</i> (<i>GmRbcS8</i>) exhibited the highest expression level compared to other members, especially in leaves. Moreover, differential expressions of <i>GmRbcS</i> genes were found to be significantly regulated by exogenous plant hormones, demonstrating their potential functions in diverse biology processes. Finally, the function of <i>GmRbcS8</i> in enhancing soybean resistance to soybean mosaic virus (SMV) was further determined through the virus-induced gene silencing (VIGS) assay. All these findings establish a strong basis for further elucidating the biological functions of <i>RbcS</i> genes in soybeans.