First molecular analysis of wisteria vein mosaic virus in Italy: eight new variants reported in Wisteria sinensis

Abstract

Wisteria vein mosaic virus (WVMV) is a potyvirus infecting Wisteria spp. worldwide, making these largely used ornamental plants unattractive and even unsalable. In 2021, nine Wisteria sinensis plants in Sarzana (Liguria, Italy) showing WVMV symptoms like vein mosaic with irregular patterns, mottling, deformation and twisting margin on leaves were reported. This work describes research on symptomatic and asymptomatic leaves to confirm the identity of the virus infection. All plants tested resulted positive to WVMV. Sequencing of NIb/CP genomic region and comparison on GenBank revealed the presence of eight new genetic variants named Sar 5–12. The eight nucleotide sequences alignments revealed identity ranging between 87.13 and 99.85%. Negative selection (dN/dS < 1) was detected suggesting well adaptation in the area here examined and stability in population. Through a phylogenetic tree, WVMV isolates were grouped in four clades with high bootstrap values, two of which included the eight Italian variants here identified. Since the late 1950 and 1960s, the present study represents the first additional report of WVMV in Italy, as well as its first molecular characterization ever. Further research is required to strengthen our understanding of the movement and transmission of WVMV. Examining how virus infected plants can disseminate this pathogen could help forestall potential risks that neighbouring species may face in their environments.