Soybean Cytochrome b5 Is a Restriction Factor for Soybean Mosaic Virus

Abstract

Soybean mosaic virus (SMV) is one of the most destructive viral diseases in soybeans (Glycine max). In this study, an interaction between the SMV P3 protein and cytochrome b5 was detected by yeast two-hybrid assay, and bimolecular fluorescence complementation assay showed that the interaction took place at the cell periphery. Further, the interaction was confirmed by co-immunoprecipitation analysis. Quantitative real-time polymerase chain reaction analysis revealed that <i>GmCYB5</i> gene was differentially expressed in resistant and susceptible soybean plants after inoculation with SMV-SC15 strain. To test the involvement of this gene in SMV resistance, the <i>GmCYB5</i> was silenced using a bean pod mottle virus (BPMV)-based vector construct. Results showed that <i>GmCYB5-1</i> was 83% and 99% downregulated in susceptible (NN1138-2) and resistant (RN-9) cultivars, respectively, compared to the empty vector-treated plants. Silencing of <i>GmCYB5</i> gene promotes SMV replication in soybean plants. Our results suggest that during SMV infection, the host CYB5 protein targets P3 protein to inhibit its proliferation. Taken together, these results suggest that CYB5 is an important factor in SMV infection and replication in soybeans, which could help soybean breeders develop SMV resistant soybean cultivars.