Transboundary Phylogenetic Connectivity of Four Garlic Virus Species in Asia: Implications for Disease Management

Abstract

Garlic (Allium sativum L.) is propagated predominantly through cloves, a production practice that enables viruses to persist and accumulate in seed stocks across successive cropping cycles and increases the risk of viral spread within and between countries. The garlic virus disease complex is associated with a diverse range of viruses, including the following four viruses: leek yellow stripe virus (LYSV), onion yellow dwarf virus (OYDV), garlic common latent virus (GarCLV), and shallot latent virus (SLV). LYSV and OYDV, both members of the genus Potyvirus, commonly induce conspicuous symptoms such as yellow striping, mosaic, stunting, and yield reduction. In contrast, GarCLV and SLV, members of the genus Carlavirus, often cause latent infections when present alone, but can contribute substantially to symptom intensification and progressive seed clove degeneration in mixed infections. This review investigated the pathological characteristics and phylogenetic relationships of these four garlic viruses, with emphasis on isolates reported from South Korea, China, Japan, and Indonesia, which represent major garlic-producing and garlic-consuming countries in Asia. Phylogenetic analyses indicate that LYSV, OYDV, GarCLV, and SLV isolates are not strictly separated according to national origin, but instead form shared or closely related lineages across countries. These patterns suggest that transboundary connectivity and local diversification within regional production systems have jointly shaped the population structure of major garlic viruses. On the basis of these pathological and phylogenetic findings, this review discusses future directions for garlic virus research in Korea.