Characterization of a Proposed Dichorhavirus Associated with the Citrus Leprosis Disease and Analysis of the Host Response

Abstract

The causal agents of Citrus leprosis are viruses; however, extant diagnostic methods to identify them have failed to detect known viruses in orange, mandarin, lime and bitter orange trees with severe leprosis symptoms in Mexico, an important citrus producer. Using high throughput sequencing, a virus associated with citrus leprosis was identified, belonging to the proposed Dichorhavirus genus. The virus was termed Citrus Necrotic Spot Virus (CNSV) and contains two negative-strand RNA components; virions accumulate in the cytoplasm and are associated with plasmodesmata—channels interconnecting neighboring cells—suggesting a mode of spread within the plant. The present study provides insights into the nature of this pathogen and the corresponding plant response, which is likely similar to other pathogens that do not spread systemically in plants.

The family Rhabdoviridae: mono- and bipartite negative-sense RNA viruses with diverse genome organization and common evolutionary origins

“…Citrus leprosis virus nuclear type (CiLV-N) and citrus necrotic spot virus appear to be strains of OFV based on 90% or higher genome sequence identity (Cruz-Jaramillo et al, 2014; Dietzgen et al, 2014; Roy et al, 2015). By degradome sequencing, a distinct CiLV-N isolate was also found in a herbarium citrus specimen from Florida in 1948 (Hartung et al, 2015).…”

Phylogenetic and Molecular Variability Studies Reveal a New Genetic Clade of Citrus leprosis virus C

“…After the 1960s, the disease disappeared from Florida [ 6 ], but in the Southern region of South America it became prevalent occurring in most of the Brazilian citrus growing areas [ 7 , 8 ]. More recently, Bolivia, Colombia, Venezuela, all of the Central American countries and Mexico have been incorporated to the citrus leprosis distribution map [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Outside of mainland America, symptoms associated with citrus leprosis have been confirmed only in Hawaii, USA [ 20 , 21 ].…”

Pest categorisation of Citrus leprosis viruses

“…More recently, other viruses causing similar leprosis symptoms in Citrus and having the same transmission biology have been described. These include a virus related to CiLV‐C identified in Colombia and termed Citrus leprosis virus Cytoplasmic Type 2 (CiLV‐C2, genus Cilevirus ; Roy et al., ), a virus named HGSV‐2 (genus Higrevirus ) observed causing symptoms in Citrus volkameriana in Hawaii (Melzer et al., ) and a virus causing leprosis symptoms in citrus in Mexico and named CiNSV (genus Dichorhavirus , Cruz‐Jaramillo et al., ).…”

“…While mandarins, lime and grapefruit are considered resistant to CiLV‐C, these citrus species, in addition to sweet orange, are susceptible to infection with the Citrus strain of OFV (Cruz‐Jaramillo et al., ; Roy et al., ,b). 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., ).…”