Identification and characterization of a pear chiorotic leaf spot-associated virus, a novel emaravirus associated with a severe disease of pear trees in China

Abstract

Pear chiorotic leaf spot (PCLS) is a recently emerged disease of commercially cultivated sandy pear (Pyrus pyrifolia) trees in central and southern China. By integrating high-throughput sequencing and conventional Sanger sequencing of reverse-transcription (RT)-PCR products, a novel emaravirus infecting pear trees was identified and molecularly characterized. The virus was provisionally named pear chlorotic leaf spot- associated virus (PCLSaV). PCLSaV shows the typical molecular features of members of the genus Emaravirus in the family Fimoviridae. It has a genome composed of at least five negative-sense RNA segments, with each containing a single open reading frame and two complementary 13-nucleotide stretches at the 5' and 3' termini. PCLSaV shows a close phylogenetic relationship with recogniied emaraviruses hut forms a separate dade. Moreover, double-membrane-bound bodies were observed in PCLSaV-infected tissues and in extracts of PCLSaV-infected leaves. For the first time, our study revealed the profile distribution of viral RNA reads from the RNA-seq libraries of three samples along the RNAI to RNA5 of an emaravinis. Field surveys combined with specific RT-PCR assays revealed the presence of PCLSaV in almost all PCLSdiseased pear samples, strongly supporting the association of the virus with the PCLS disease. This study revealed the first emaravirus infecting pear trees and its association with a severe pear chlorotic leaf disease.