Signaling Pathway Analysis and Downstream Genes Associated with Disease Resistance Mediated by GmSRC7

<i>GmSRC7</i> is a broad-spectrum antiviral <i>R</i> gene from soybean, but its downstream and functionally related genes remain unclear. Virus-induced gene silencing (VIGS) assays in <i>Nicotiana benthamiana</i> (<i>Nb</i>) showed that suppression of several gene families-WRKY transcription factors, chaperones, ethylene pathway components, MAPK cascade elements, salicylic acid (SA) signaling genes, calcium-dependent protein kinases, nuclear migration proteins, RNA replication-related genes, and immune regulators-consistently weakened <i>GmSRC7</i>-mediated resistance to Soybean Mosaic Virus (SMV) and Tobacco Mosaic Virus (TMV). Targeted silencing of four regulatory genes-<i>NbEDS1</i>, <i>NbARF1</i>, <i>NbSGT1</i>, and <i>NbCOI1</i>-markedly enhanced <i>GmSRC7</i>-mediated resistance to SMV and TMV in our experiments. Silencing the serine/threonine kinase gene <i>NbPBS1</i> increased <i>GmSRC7</i>-conferred resistance to SMV but did not significantly alter its resistance to TMV. Transient expression assays showed that <i>NbARF1</i>, <i>NbSGT1</i>, and <i>NbCOI1</i> antagonize <i>GmSRC7</i>-mediated defense against SMV and TMV, whereas <i>NbPBS1</i> specifically suppresses anti-SMV activity without affecting TMV resistance. Transient overexpression of SA-degrading enzymes (<i>AtS3H</i>, <i>AtS5H</i>, and <i>NahG</i>) significantly reduced <i>GmSRC7</i>-conferred resistance to SMV, indicating that SA is essential for this R protein-mediated defense. Genes were also grouped by immune pathways and function: co-expression of chaperone family genes inhibited <i>GmSRC7</i> activity against SMV and TMV, while co-expression of WRKY family genes enhanced anti-SMV activity of <i>GmSRC7</i>. Finally, transient silencing of soybean genes <i>GmEDS1</i>, <i>GmSGT1-1</i>, <i>GmSGT1-2</i>, <i>GmJAR1</i>, and <i>GmSGS3</i> compromised <i>GmSRC7</i>-mediated resistance to SMV.