Ilarviruses ofPrunusspp.: A Continued Concern for Fruit Trees

Abstract

Prunus spp. are affected by a large number of viruses, causing significant economic losses through either direct or indirect damage, which results in reduced yield and fruit quality. Among these viruses, members of the genus Ilarvirus (isometric labile ringspot viruses) occupy a significant position due to their distribution worldwide. Although symptoms caused by these types of viruses were reported early in the last century, their molecular characterization was not achieved until the 1990s, much later than for other agronomically relevant viruses. This was mainly due to the characteristic liability of virus particles in tissue extracts. In addition, ilarviruses, together with Alfalfa mosaic virus, are unique among plant viruses in that they require a few molecules of the coat protein in the inoculum in order to be infectious, a phenomenon known as genome activation. Another factor that has made the study of this group of viruses difficult is that infectious clones have been obtained only for the type member of the genus, Tobacco streak virus. Four ilarviruses, Prunus necrotic ringspot virus, Prune dwarf virus, Apple mosaic virus, and American plum line pattern virus, are pathogens of the main cultivated fruit trees. As stated in the 9th Report of the International Committee on Taxonomy of Viruses, virions of this genus are "unpromising subjects for the raising of good antisera." With the advent of molecular approaches for their detection and characterization, it has been possible to get a more precise view of their prevalence and genome organization. This review updates our knowledge on the incidence, genome organization and expression, genetic diversity, modes of transmission, and diagnosis, as well as control of this peculiar group of viruses affecting fruit trees.

Dynamics of Prunus Necrotic Ringspot and Apple Mosaic Ilarviruses in Stone Fruits - A Serological Perspective

“…The present survey has shown that the level of Ilarvirus infections in stone fruit trees in mid hill zone of Himachal Pradesh is lower than that reported from other parts of the world (DiTerlizzi et al, 1992;Aouane, 2003;Polak, 2007;Matic et al, 2008;Scott 2014;Pallas et al, 2012) (Fig. 1-8).…”

“…Prunus necrotic ringspot virus (PNRSV) and apple mosaic virus (ApMV) are common and widespread in different stone fruits causing crop losses (Scott, 2014;Pallas et al, 2012). In India, little is known on virus diseases of stone fruit trees and records are limited on the occasional finding of ilarviruses (PNRSV and ApMV) in major stone fruits grown in India (Kapoor and Handa, 2017a;Chandel et al, 2013).…”

Ilarviruses and the Importance of Certified Elite Planting Material in Apple Production System - An Overview

“…Scott (2018) studied the effect of prunus necrotic ring spot virus on growth, yield and quality of peach and found a reduction in tree growth between 12 to 70 percent and yield loss of 5 to 70 percent with fruits having lower soluble sugar content. PNRSV has also been reported to cause significant crop losses depending on the host (15 percent yield loss in sweet cherry and up to 100 percent in peach) and can reduce bud-take in nurseries, decrease growth of fruit from 10 to 30 percent and fruit yield reduction from 20 to 60 percent with delayed fruit maturity (Pallas et al, 2012).…”

Correlating Field Symptoms of PNRSV with DAC and DAS-ELISA based Serological Detection

“…Incidence of PNRSV was reported to be 60 percent in Georgia (Wells et al,1986); 25 percent in Turkey (Gumus et al, 2007); 70 and 100 percent in South Carolina (Scott 2014); 30 percent in Canada (Pallas et al, 2012); 25 percent in Mexico (Almaraz 2008); 32 percent in Saudi Arabia (Alhudaib and Rezk 2011); 15 percent in Central Bohemia, Czech Republic (Winkowska et al, 2016) and 18 percent in India (Kapoor and Handa 2017a Orchard-5 Jaunaji 10…”