Citrus leprosis virus N: A New Dichorhavirus Causing Citrus Leprosis Disease

Abstract

Citrus leprosis (CL) is a viral disease endemic to the Western Hemisphere that produces local necrotic and chlorotic lesions on leaves, branches, and fruit and causes serious yield reduction in citrus orchards. Samples of sweet orange (Citrus × sinensis) trees showing CL symptoms were collected during a survey in noncommercial citrus areas in the southeast region of Brazil in 2013 to 2016. Transmission electron microscopy analyses of foliar lesions confirmed the presence of rod-like viral particles commonly associated with CL in the nucleus and cytoplasm of infected cells. However, every attempt to identify these particles by reverse-transcription polymerase chain reaction tests failed, even though all described primers for the detection of known CL-causing cileviruses and dichorhaviruses were used. Next-generation sequencing of total RNA extracts from three symptomatic samples revealed the genome of distinct, although highly related (>92% nucleotide sequence identity), viruses whose genetic organization is similar to that of dichorhaviruses. The genome sequence of these viruses showed <62% nucleotide sequence identity with those of orchid fleck virus and coffee ringspot virus. Globally, the deduced amino acid sequences of the open reading frames they encode share 32.7 to 63.8% identity with the proteins of the dichorhavirids. Mites collected from both the naturally infected citrus trees and those used for the transmission of one of the characterized isolates to Arabidopsis plants were anatomically recognized as Brevipalpus phoenicis sensu stricto. Molecular and biological features indicate that the identified viruses belong to a new species of CL-associated dichorhavirus, which we propose to call Citrus leprosis N dichorhavirus. Our results, while emphasizing the increasing diversity of viruses causing CL disease, lead to a reevaluation of the nomenclature of those viruses assigned to the genus Dichorhavirus. In this regard, a comprehensive discussion is presented.

Revisão taxonômica do ácaro da leprose dos citros e sua distribuição no Brasil

“…Sabe-se atualmente que algumas linhagens de B. yothersi (tanto de citros quanto de cafeeiro) mantidas em laboratório no Instituto Biológico e no Centro de Citricultura do IAC, apresentam a capacidade de aquisição e transmissão de vírus, tanto da leprose dos citros quanto da mancha anular do cafeeiro (Ramos- González et al, 2016González et al, , 2017Nunes et al, 2017).…”

“…A maioria das espécies que causam danos econômicos a plantas cultivadas, incluindo ornamentais, pertence ao gênero Brevipalpus (Jeppson et al, 1975;Childers & Rodrigues, 2011 (Chagas, 1973;Ochoa et al, 1994;Chagas et al, 2001Chagas et al, , 2003Childers et al, 2001;Rodrigues et al, 2008;Kitajima et al, 2010;Rodrigues & Childers, 2013;Alberti & Kitajima, 2014;Ramos-González et al, 2017;Nunes et al, 2017).…”

Pest categorisation of Citrus leprosis viruses

“…Lemon and sour orange have also been found naturally infected (Cruz‐Jaramillo et al., ; Roy et al., ,b) and Dieffenbachia and Swinglea are also alternative natural hosts. Sampling in non‐commercial C. sinensis orchards in Brazil identified that a further distinct rhabdovirus species with the proposed name CiLV‐N is causing there a nuclear‐type leprosis disease (Ramos‐Gonzalez et al., ). While not identified anywhere else, this finding confirms that further and diverse rhabdoviruses cause the leprosis disease.…”

“…CiLV-N sensu novo is also known to have significant intraspecific diversity at the genome level, with divergence values of between 2% and 8% reported between four Brazilian isolates (Ramos-Gonzalez et al, 2017).…”

“…; Roy et al, 2013Roy et al, , 2015a. CiLV-N has recently been shown to be transmitted by B. phoenicis sensu stricto (Ramos-Gonzalez et al, 2017). Based on their association in the field, isolates of the Citrus strain of OFV are believed to be transmitted by B. californicus.…”