Molecular Epidemiology and Genetic Diversity of Beet Necrotic Yellow Vein Virus (BNYVV) in Sugar Beet Fields

Abstract

Beet Necrotic Yellow Vein Virus (BNYVV), the causal agent of rhizomania disease, is one of the most destructive viral pathogens affecting sugar beet production worldwide. The disease is characterized by excessive root proliferation, leaf chlorosis, stunted growth, and significant reductions in root yield and sugar content. The widespread distribution of BNYVV and its persistence in soil through the vector Polymyxa betae make disease management particularly challenging. The present study was conducted to investigate the molecular epidemiology and genetic diversity of BNYVV populations in major sugar beet cultivation areas. Field surveys were carried out across infected production regions, and symptomatic sugar beet plants exhibiting typical rhizomania symptoms were collected for laboratory analysis. Total RNA was extracted from infected root tissues and subjected to reverse transcription polymerase chain reaction (RT-PCR) using BNYVV-specific primers targeting conserved viral genomic regions. Amplified products were sequenced and analyzed using BLAST and phylogenetic methods to determine genetic variability, evolutionary relationships, and distribution patterns among viral isolates. Epidemiological data, including disease incidence, field distribution, and environmental conditions, were also evaluated to understand factors influencing virus spread. The results confirmed the widespread occurrence of BNYVV in surveyed sugar beet fields, with infected plants showing severe root abnormalities and reduced plant vigor. Molecular analysis revealed considerable genetic diversity among viral isolates, indicating the presence of multiple strain groups and regional variation within the virus population. Phylogenetic analysis demonstrated close relationships between local isolates and previously reported international strains, suggesting possible movement of infected plant material and long-term adaptation of the virus in sugar beet production systems. Environmental conditions and vector abundance were found to significantly influence disease incidence and distribution.