Detection and Characterization of Potato Virus Y (PVY) Strains and Mixed Infections in San Luis Valley, Colorado

Abstract

Potato virus Y (PVY) is a major economic threat to potato production worldwide. Understanding the prevalent PVY strains and their dynamics is crucial for effective management. This study investigated PVY trends and diversity in the San Luis Valley (SLV), Colorado, USA. We leveraged the Colorado Seed Potato Certification Program data (2017 – 2022), revealing a persistent problem with PVY incidence in certified seed lots that fluctuated between 2.6% (2017) and 6.5% (2022). PVYN-Wi was the dominant strain, with others such as PVYO, also detected. A complementary field study (2021-2022) investigated PVY prevalence and diversity in 600 samples collected from 30 fields. PVYN-Wi was identified as the main strain, followed by PVYO and PVYNTN. Notably, the incidences of dual and triple infections, along with inconclusive samples, increased in both post-harvest t and field study samples. High-throughput sequencing (HTS) of the inconclusive samples identified from the field study samples determined PVYN-Wi as the predominant strain and identified polymorphisms that may hinder accurate identification by traditional strain typing methods. Beyond PVY, potato virus S (PVS) was the only other major potato-infecting virus detected. HTS revealed diverse non-plant infecting viruses as well. This study provides valuable insights into the evolving PVY landscape and the complex potato virome in SLV. It highlights the importance of continued surveillance and improved diagnostics to mitigate the impact of viruses on potato production.