PVX

PVX, or Potato Virus X, is a positive-sense RNA plant virus belonging to the family Alphaflexiviridae and the genus Potexvirus. It primarily affects solanaceous crops, most notably potato (Solanum tuberosum), causing symptoms such as mosaic or mottling, leaf curling, chlorosis, and stunting, which can lead to reduced yields. The virus is more severe in fields with high aphid activity or where infected planting material is used.

Structure and genome: PVX virions are flexuous, filamentous particles about 640–750 nanometers in length. The genome is a single-stranded positive-sense RNA of approximately 6.4 kilobases, with a 5' cap and a 3' poly(A) tail. The genome encodes five open reading frames: a replication-associated RNA-dependent RNA polymerase, three movement proteins (TGB1, TGB2, TGB3), and a coat protein. The movement proteins coordinate cell-to-cell and systemic movement through plasmodesmata.

Transmission and host range: PVX is mainly transmitted mechanically through damaged tissue and nonpersistently by several aphid species. It is not typically seed- or pollen-transmitted. The virus has a relatively narrow host range within Solanaceae, including potato and tomato, among other related crops.

Diagnosis and management: Diagnosis relies on serological assays (ELISA) and molecular methods (RT-PCR). Management emphasizes using virus-free seed tubers, rogueing of infected plants, sanitation of tools, and controlling aphid vectors. Cultivars with PVX resistance genes, such as Rx1, provide resistance by limiting replication and movement. PVX is also widely used as a model organism in plant virology and as a backbone for viral vectors in biotechnology to study gene expression and protein localization.