Detection and identification of soy viruses by molecular diagnostics methods

Viral plant diseases are one of the main causes of soybean crop losses in Ukraine, and the lack of systematic monitoring and limited use of modern diagnostic methods make it difficult to effectively control the spread of viral pathogens. The purpose of the study was to assess the prevalence of major viral pathogens in soybean crops in the Central Forest-Steppe of Ukraine. A combination of serological analysis and molecular method was used to detect soybean mosaic virus, soybean vein necrosis virus, and alfalfa mosaic virus. The results showed that the overall infection rate of soybean crops was 40.7% according to real-time polymerase chain reaction data with reverse transcription. The species composition of pathogens showed clear differentiation: soybean mosaic virus was detected in 20.0% of samples, soybean vein necrosis virus – in 8.0%, alfalfa mosaic virus – in 7.3%. The real-time reverse transcription polymerase chain reaction method showed higher sensitivity compared to the enzyme-linked immunosorbent assay method, revealing an additional 13 positive samples. The most significant discrepancies between the methods were observed when detecting alfalfa mosaic virus, where the molecular method detected 50% more positive samples. Regional analysis revealed the highest infection rate in the Cherkasy Oblast (44.0%), with the maximum prevalence of soybean mosaic virus (22.0%). A moderate correlation was found between symptom severity and threshold cycle values for soybean mosaic virus (r = -0.62), whereas for soybean vein necrosis virus and alfalfa mosaic virus, the correlation was statistically insignificant. The results confirmed the high prevalence of viral infections among soybean crops in the study region. The results obtained will allow stating phytosanitary services, breeding institutions, and agricultural producers to implement regional-differentiated strategies for protecting soybeans, which will reduce crop losses and increase the effectiveness of phytosanitary measures