Molecular Characterization and Sequence Diversity of Grapevine Virus A (GVA) Isolates in Commercial Vineyards

Abstract

Grapevine Virus A (GVA) is one of the economically important viruses associated with grapevine decline and reduced fruit quality in commercial vineyards worldwide. The present study was undertaken to investigate the molecular characterization and sequence diversity of GVA isolates infecting grapevine plants collected from major commercial vineyards showing symptoms such as leaf curling, stem grooving, reduced vigor, and poor berry development. Total RNA was extracted from symptomatic samples and subjected to reverse transcription polymerase chain reaction (RT-PCR) using GVA-specific primers targeting the coat protein gene. Amplified products of the anticipated size were purified, sequenced, and compared with existing GVA sequences available in GenBank. Sequence analysis revealed significant genetic variability among the obtained isolates, indicating the presence of diverse GVA strains within vineyard populations. Phylogenetic analysis grouped the isolates into distinct clusters with previously reported international isolates, suggesting possible evolutionary divergence and regional adaptation. Multiple sequence alignment identified nucleotide substitutions and minor sequence polymorphisms in the coat protein region, which may contribute to variability in virulence and symptom expression. The findings provide valuable insights into the molecular epidemiology and genetic diversity of GVA infecting commercial grapevine cultivars. Understanding the sequence variability of GVA isolates is essential for accurate diagnostics, certification programs, and the development of effective disease management strategies. This study represents an important contribution toward the characterization of GVA populations and supports future research on grapevine virus evolution and host–pathogen interactions in viticulture systems.