Molecular identification and characterization of soybean mosaic virus isolates from Serbia

Certified and non-certified seed of the soybean cultivar Dukat showing symptoms of mottling were collected at the preharvest stage from soybean fields in the location Tamiš (South Banat District, Serbia) in 2021. To identify the presence of soybean mosaic virus (SMV), a total of 10 samples, five of each type of seed, were selected and tested by RT-PCR using primers SMVCPF/SMVCPR, which amplify a fragment of the coat protein (CP) gene. The molecular assay confirmed the presence of SMV in all tested seed samples. For further analyses, the CP and P1 genome regions of two selected isolates (DS-21 and NDS-21, representing certified and noncertified seed, respectively) were partially sequenced. The Serbian SMV isolates shared very low nucleotide diversity and were mutually closely related based on the CP (99.8% nt/99.2% aa identities) and P1 (99.7% nt/ 99.6% aa identities) regions. Phylogenetic analyses based on both genomic regions showed that the two Serbian SMV isolates originating from certified and noncertified seed belonged to one cluster, and consequently to the same SMV subpopulation. Since this is the first molecular characterization of SMV in Serbia, further research should be focused on collecting samples from different locations and of different varieties, and on determining the variability of SMV population in Serbia based on whole-genome analysis. This research will contribute to better understanding of the epidemiology of this pathogen with the ultimate goal of developing and implementing appropriate control measures.