Molecular Epidemiology and Coat Protein Diversity of Beet Curly Top Virus in Sugar Beet Production Areas

Abstract

Beet curly top disease, caused by Beet curly top virus (BCTV), continues to pose a significant threat to sugar beet productivity in major cultivation zones, necessitating detailed molecular epidemiological investigations for effective management. Field surveys were conducted across representative sugar beet production areas to collect symptomatic plants exhibiting curling, chlorosis, stunting, and vein thickening. Total DNA extracted from infected samples was subjected to PCR amplification using virus-specific primers targeting the coat protein (CP) gene. Amplified products were sequenced and analyzed to determine genetic variability and phylogenetic relationships among circulating isolates. Sequence comparison revealed notable nucleotide diversity within the CP region, indicating the presence of multiple BCTV strains co-infecting agricultural landscapes. Phylogenetic analysis grouped the isolates into distinct clades closely related to previously reported strains from different geographic regions, suggesting possible introductions through seed movement and vector migration. Amino acid substitutions in conserved coat protein domains were identified, potentially influencing virus-host interactions and transmission efficiency by leafhopper vectors. Molecular variability was found to correlate with differences in symptom severity observed in field conditions, indicating strain-dependent pathogenicity. Epidemiological assessments highlighted higher disease incidence in areas with warmer temperatures and dry conditions favorable for vector proliferation. The study underscores the importance of continuous molecular surveillance to track BCTV evolution and spread within sugar beet agroecosystems. These findings provide critical insights into virus diversity, aiding in the development of resistant cultivars and targeted disease management strategies. Integration of molecular diagnostics with field epidemiology offers a robust framework for managing curly top disease and mitigating yield losses in sugar beet production systems under changing environmental and agricultural practices.