Molecular and Biological Characterization of a Newly Identified Virus Representing a Novel Taxon of Alphaflexiviridae Infecting Different Accessions of Seashore Paspalum, a Turfgrass, Widely Grown in the United States.

Seashore paspalum (Paspalum vaginatum), a salinity-tolerant turfgrass, lacks well-characterized viral profiles. This study reports the discovery of a novel virus, tentatively named Paspalum latent virus (PaLV), representing a new taxon within the Alphaflexiviridae. Using high-throughput sequencing and RACE PCR, the 6995 nt genome was determined, revealing five open reading frames. Notably, PaLV lacks the AlkB domain and exhibits unique features, including overlapping start-stop codons (ORF4/ORF5) and a second in-frame AUG in the coat protein (CP) region. Phylogenetic analysis of the replicase placed PaLV in a distinct clade, separate from Potexvirus and Lolavirus. Despite low sequence identity, AlphaFold2 revealed conserved CP structural domains. Genetic analysis of 11 isolates showed low diversity and strong purifying selection. Pathogenicity assays through mechanical transmission demonstrated a broad but latent host range, including Zea mays and Sorghum spp. These findings suggest PaLV represents a novel species within a putatively new genus, Paspalovirus. Given its 90% incidence rate and latent profile, the RT-PCR assay developed here is vital for routine molecular diagnostics in turfgrass management and germplasm conservation.