GRAPEVINE FANLEAF VIRUS: STILL A MAJOR THREAT TO THE GRAPEVINE INDUSTRY

Abstract

SUMMARY Grapevine fanleaf virus (GFLV) is responsible for fanleaf degeneration, which is one of the most severe virus diseases of grapevines worldwide. GFLV causes substantial crop losses, reduces fruit quality and shortens the longevity of grapevines in the vineyard. GFLV is transmitted specifically from grapevine to grapevine by the ectoparasitic nematode Xiphinema index, and belongs to the genus Nepovirus in the family Comoviridae. Since the discovery of the nematode vector in the late 1950’s and the identification of GFLV as the agent responsible for fanleaf degeneration in the early 1960’s, a wealth of information has been accumulated on its transmission, biological properties and serological characteristics, as well as on the structure and expression of the GFLV genome. Although dissemination of the virus through propagation material has been drastically reduced over the past two decades by implementing rigorous certification schemes and establishing quarantine facilities, effective strategies are still needed to control GFLV in naturally infected vineyards. Recently, significant progress has been made on the elucidation of the function(s) of most GFLV proteins, in particular those involved in critical steps of the virus multiplication cycle, including RNA replication, cell-to-cell movement, and transmission by X. index. New insights have also been gained into the population structure and genomic variability among isolates from naturally infected vineyards, which have opened new avenues for designing alternative strategies to control this destructive virus. This review article offers a comprehensive overview of the most significant advances made over the past 15 years on GFLV and discusses novel control strategies for one of the major threats to the grapevine industry worldwide.