Seasonal Incidence and Molecular Characterization of Beet Western Yellows Virus in Oilseed Rape Fields

Abstract

Seasonal incidence and molecular characterization of Beet western yellows virus (BWYV) in oilseed rape fields were investigated to determine disease dynamics, distribution patterns, and genetic identity of the virus. Field surveys were conducted across major oilseed rape-growing regions, and plants exhibiting symptoms such as interveinal yellowing, reddening, stunting, and reduced pod formation were systematically recorded. Symptomatic and asymptomatic samples were collected throughout the growing season to assess temporal disease incidence. Viral detection was carried out using RT-PCR targeting conserved genomic regions, followed by sequencing for molecular characterization. Results indicated clear seasonal fluctuations in BWYV incidence, with peak infection levels observed during periods of high aphid activity and favorable climatic conditions. Early-season infections were associated with more severe yield reduction due to prolonged systemic virus spread, while late-season infections showed comparatively limited impact. Molecular analysis confirmed the identity of BWYV in infected samples, with sequence comparisons revealing high similarity to global isolates and minor nucleotide variations indicative of regional diversification. Phylogenetic analysis grouped the isolates within established BWYV clades, confirming their evolutionary relatedness and suggesting aphid-mediated long-distance dissemination. The study highlights the strong relationship between vector population dynamics, seasonal environmental conditions, and BWYV incidence in oilseed rape. These findings emphasize the importance of timely monitoring and integrated vector management strategies to reduce virus spread and minimize yield losses in oilseed rape production systems.