Molecular Detection and Sequence Diversity of Potato Leafroll Virus (PLRV) Isolates in Seed Potato Production

Abstract

Molecular detection and sequence characterization of Potato leafroll virus (PLRV) were carried out in seed potato (Solanum tuberosum L.) production systems to assess viral incidence and genetic variability among field isolates. Symptomatic and asymptomatic leaf samples were collected from commercial seed potato fields and subjected to reverse transcription polymerase chain reaction (RT-PCR) using PLRV-specific primers targeting the coat protein gene. Amplification confirmed the presence of PLRV in a significant proportion of symptomatic samples, while a lower incidence was also detected in asymptomatic plants, indicating latent infection and potential cryptic spread within planting material. Sequencing of representative isolates revealed nucleotide variations among field populations, with phylogenetic analysis clustering them into closely related but distinct subgroups within globally reported PLRV strains. Sequence alignment indicated conserved regions within the coat protein gene, although point mutations and minor indels suggested ongoing molecular evolution and localized adaptation. Phylogenetic reconstruction demonstrated genetic proximity to isolates reported from major potato-growing regions, supporting the hypothesis of seed-borne dissemination and movement of infected planting material. The study highlights the critical role of molecular diagnostics in early detection and certification of virus-free seed stocks to prevent yield losses associated with PLRV-induced physiological disorders such as leaf rolling, chlorosis, and tuber yield reduction. Implementation of routine RT-PCR-based screening combined with clean seed programs is essential for effective virus management. These findings contribute to understanding PLRV genetic diversity and epidemiology in seed potato systems and support the development of robust disease management strategies for sustainable potato production.