Probing into the Effects of Grapevine Leafroll-Associated Viruses on the Physiology, Fruit Quality and Gene Expression of Grapes

Abstract

Grapevine leafroll is one of the most widespread and highly destructive grapevine diseases that is responsible for great economic losses to the grape and wine industries throughout the world. Six distinct viruses have been implicated in this disease complex. They belong to three genera, all in the family Closteroviridae. For the sake of convenience, these viruses are named as grapevine leafroll-associated viruses (GLRaV-1, -2, -3, -4, -7, and -13). However, their etiological role in the disease has yet to be established. Furthermore, how infections with each GLRaV induce the characteristic disease symptoms remains unresolved. Here, we first provide a brief overview on each of these GLRaVs with a focus on genome structure, expression strategies and gene functions, where available. We then provide a review on the effects of GLRaV infection on the physiology, fruit quality, fruit chemical composition, and gene expression of grapevine based on the limited information so far reported in the literature. We outline key methodologies that have been used to study how GLRaV infections alter gene expression in the grapevine host at the transcriptomic level. Finally, we present a working model as an initial attempt to explain how infections with GLRaVs lead to the characteristic symptoms of grapevine leafroll disease: leaf discoloration and downward rolling. It is our hope that this review will serve as a starting point for grapevine virology and the related research community to tackle this vastly important and yet virtually uncharted territory in virus-host interactions involving woody and perennial fruit crops.

Genome-wide screening of novel RT-qPCR reference genes for study of GLRaV-3 infection in wine grapes and refinement of an RNA isolation protocol for grape berries

“…GLRaV-3 was reported to form viral replication complexes in association with mitochondrial membrane of infected host cells [102][103][104]. It is hypothesized that GLRaV-3 infections cause damages to mitochondria; and that genes associated with mitochondrial processes would be differentially regulated in GLRaV-3-infected grapevines [70]. Interestingly, results from our study and those reported by others [44,57,86,97] have identified some of the genes involved in respiration as being stably expressed.…”

“…The most characteristic symptoms of GLRaV-3-infection in dark-skinned grapevine cultivars are the downward curling of leaf margins and red to purple pigmentation of interveinal regions in leaves [70]. The discoloration of GLRaV-3-infected leaves is associated with increased biosynthesis of anthocyanins, likely resulting from the up-regulation of UFGT gene [4].…”

“…Grapevine leafroll-associated virus 3 (GLRaV-3) is a positive-sense, single-stranded RNA (ssRNA) virus of the Ampelovirus genus within the family Closteroviridae [69]. It is one of the major grapevine viruses with a worldwide prevalence and is the main agent associated with grapevine leafroll disease (GLRD); the most prevalent and destructive viral disease of grapevine that afflicts global grape and wine production [70][71][72]. Infection with GLRaV-3 can result in significant yield reduction and altered fruit chemistry that negatively impact the quality of fresh fruits, juice and wine, as well as the profitability and lifespan of vineyards [71,73].…”

Molecular Acquisition, Cleaning and Evaluation in R (MACER) - A tool to assemble molecular marker datasets from BOLD and GenBank

“…The use of molecular sequence data is an essential component of many analyses across various fields of scientific study, including virology ( Radford et al 2012 ), gene expression studies ( Song et al 2021 ), evolutionary biology ( Hudson 2008 ), taxonomy and species identifications ( Hubert and Hanner 2015 ) and biodiversity surveys ( Young et al 2021 ). One of the strengths of molecular approaches is in the comparability of the data, even when obtained by different labs and researchers.…”

Lipid Peroxidation Level and Peroxidase Activity in (Vitis vinifera L.) Leaves Infected with Grapevine Leafroll-Associated Virus 3

“…Virus diseases in the grapevine have detrimental effects on the agronomic, ecological performance, and morphological changes of vines. In addition to reduced yield and quality, viruses also damage photosynthesis, chloroplast level, functions and ultrastructure, accumulation of photoassimilates (6) . Viruses also may determine leaf and cluster of morphological modifications which aid phenotypic expression of disease symptoms and exertion of plenty of other pathological changes in the plant.…”