TurboID Screening and Functional Analysis of the Interactome of the Broad-Spectrum Antiviral Protein Soybean Resistance Cluster 7 (SRC7)

Plant viral diseases cause severe yield losses in global crop production. SRC7, a novel soybean TIR-NBS-BSP-type resistance (R) protein, confers broad-spectrum antiviral immunity against multiple viruses including soybean mosaic virus (SMV), tobacco mosaic virus (TMV), potato virus Y (PVY), and plum pox virus (PPV). Its TIR-NBS domain (SRC7TN) mediates full antiviral resistance, making it an ideal bait for screening immune-related proximal candidate proteins. In this study, TurboID-based proximity labeling (PL) was applied to profile the SRC7TN proximal candidate proteins in N. benthamiana. We identified 262 high-confidence proximal candidate proteins, which were mainly enriched in plant immune signaling, redox regulation, protein modification and nuclear-related pathways. Among them, 21 candidates were functionally characterized, revealing multiple host factors contributing to SRC7-dependent antiviral immunity. Eleven interactions were confirmed via bimolecular fluorescence complementation (BiFC), and two nucleoside/nucleotide hydrolase-family proteins MZN14.5 and RIHA were subjected to further interaction-domain analysis. Collectively, this work constructs a high-confidence SRC7TN proximal-interaction network and highlights critical host factors in SRC7-mediated broad-spectrum antiviral immunity. It also validates TurboID’s utility for screening for NLR-proximal candidate proteins in heterologous plant systems and provides insights into R-protein-governed plant antiviral defense.