Transcriptome Insights into Resistance Mechanisms Against Soybean Mosaic Virus Strain SC4 in Soybean

Soybean, an economically valuable oil and protein crop, is vulnerable to numerous biotic stresses throughout its growth period. Soybean mosaic virus (SMV), a destructive plant pathogen, induces substantial yield reduction and seed quality deterioration globally. In China, a total of 22 distinct SMV strains have been documented, with SMV-SC4 being a widely spread strain. The Chinese cultivar Kefeng-1 (KF) is resistant to this strain. To investigate the resistance mechanism, transcriptional analysis was performed at 0, 6, 24, and 48 h post-inoculation of SC4 in KF (Resistant) and NN1138-2 (NN) (Susceptible). A total of 1201 core differentially expressed genes (DEGs) were identified as active ones against SC4 infection, with most originating from the resistant cultivar at the early infection stages. Gene ontology enrichment analysis indicated that the DEGs directly involved in signal transduction and those related to plant stress response contributed to KF resistance indirectly, including protein phosphorylation, protein kinase activity, oxidation–reduction, oxidoreductase activity, catalytic activity, metal ion transport, and response to auxin. A total of 27 genes in “Signal transduction” with most of them were disease resistance conserved domains, 52 genes active in oxidoreductase activity involving in removing ROS from SMV attack, and 8 genes in “Response to auxin”, a phytohormone that plays a role in biotic stress response in addition to growth and development. These genes expressed more differentially in the resistant versus susceptible cultivar. Our findings provide insights into the molecular networks related to soybean response to SMV, which may be relevant in understanding soybean resistance against the viral infections.