Grapevine leafroll-associated virus 3

Abstract

Grapevine leafroll disease (GLD) is arguably the most important virus disease of grapevine, economically on par with the foremost fungal and bacterial maladies of grapevine. This chapter reviews recent progress in research on Grapevine leafroll-associated virus 3 (GLRaV-3), the generally accepted "main etiological agent" of GLD. The molecular characterization of the ~18, 500 nt ssRNA GLRaV-3 genome and annotation of its 12 open reading frames have largely been completed, albeit functional confirmation for most ORFs is still eluding researchers. The development of infectious GLRaV-3 clones should progress this aspect significantly. The advent of next-generation sequencing (NGS) technologies allowed considerable progress in identifying the multitude of GLRaV-3 genetic variants and, through the use of metagenomic approaches, firmly established GLRaV-3 as the primary viral agent associated with GLD. The various levels of host-pathogen interactions, including the potential role of small RNAs in this complex plant-virus interaction, are receiving increasing attention with a number of studies now attempting to link biological characteristics of the virus and physiological impacts on its grapevine host. As with most virus diseases, aspects of control are focused on accurate and reliable detection and prevention of disease. Developments in GLRaV-3 detection, especially quantitative detection of the different variant groups, as well as NGS- based metagenomic approaches, are discussed. Disease eradication and management are illustrated with descriptions of a few case studies.