diversity of brevipalpus-transmitted plant viruses brevipalpus-transmitted plant viruses: an...

SCIENCE PROTECTING PLANT HEALTH 26-28 September, 2017, Brisbane, Australia

Diversity of Brevipalpus-transmitted plant viruses

EW Kitajima1, J Freitas-Astúa2,3, PL Ramos-González3 & RG Dietzgen4

1ESALQ/Universidade de São Paulo, Piracicaba, 13418-900 Piracicaba, SP, Brazil; 2Embrapa Cassava and Fruits, 4438-000 Cruz das Almas, BA, Brazil; 3Instituto Biológico, 04014-900 São Paulo, SP, Brazil; 4QAAFI, The University of Queensland, St.Lucia, QLD 4072, Australia

ewkitaji@usp.br

Fapesp/Univ.Queensland Sprint Program 2017/50039-1

Brevipalpus-transmitted plant viruses: an overview

The viruses Cytoplasmic type-

Cilevirus Higrevirus

Nuclear type Dichorhavirus

The vector Brevipalpus spp. (Tenuipalpidae)

Symptoms Localized, non systemic lesions in infected host plants

Ligustrum leprosis virus L. sinensis Brunfelsia uniflora

Hibiscus leaf infected with HGSV

Local necrotic lesions on bean leaf experimentally infected with CiLV-C

Geographic distribution of BTV (except OFV, present worldwide)

BTV- CYTOPLASMIC TYPE Cilevirus: bipartite (5 & 9 kb) ssRNA (+). Short, bacilliform, membrane bounded particles. Accumulate in the ER. Dense, vacuolated viroplasma in the cytoplasm. Type member- CiLV-C; recognized member- CiLV-C2

Higrevirus: similar but tripartite Type and sole member- HGSV-2

BTV- NUCLEAR TYPE Dichorhavirus: bipartite (2 x 6kb) ssRNA (-), member of Rhabdoviridae. Short, rod- like particles in the nucleus and cytoplasm. Electron lucent nuclear viroplasm. Type member: OFV; recognized member- CoRSV

Economically important diseases -Citrus leprosis -Coffee ringspot -Passion fruit green spot -Orchid fleck

Citrus leprosis

CoRSV

PfGSV

OFV

Genome organization of BTV

BTV-C Cilevirus CiLV-C (Locali et al., 2006)

BTV-N Dichorhavirus (Rhabdoviridae) OFV (Kondo et al., 2006)

Virus vector relationship

BTV-C persistent, circulative type

BTV-N persistent, circulative, propagative type

*

Virions (arrows) present between membranes of adjacent cells

Viroplasm (*) in the nucleus and virions either in the nucleus or in the cytoplasm (arrows)

Vector species B. phoenicis s.s. (CiLV-N), B. yothersi (CiLV-C, CiLV-C2, LigLV), B. yothersi aff. (CiCSV, ClCSV), B. papayensis (CoRSV, CiLV-C, LigRSV), B. californicus (OFV), B. obovatus (SvRSV, CesRSV)

BTV – so far, found naturally infecting more than 40 different plant species, mostly ornamental. However, few have been characterized molecularly.

Recently sequenced BTV

Cilevirus: Citrus leprosis virus C SJP (CiLV-C SJP), Solanum violaefolium ringspot virus (SvRSV), Ligustrum leprosis virus (LigLV), Passion fruit green spot virus (PfGSV)

Dichorhavirus: Citrus leprosis virus N (CiLV-N), Citrus chlorotic spot virus (CiCSV), Clerodendrum chlorotic spot virus (ClCSV), Cestrum ringspot virus (CesRSV)

Phylogenetic reconstruction based on RdRp2 (protein motif).

Cilevirus

Tobamovirus

Negevirus

Unassigned

Blunervirus

Tobravirus

Virgaviridae

Higrevirus

Closteroviridae

Ramos-González et al., 2016

BTV-C

Phylogenetic reconstruction based on nucleoprotein N.

Selected genera of the family Rhabdoviridae.

Dichorhavirus CytorhabdovirusNucleorhabdovirus Varicosavirus

Ramos-González et al., 2017

CiLV-N Br

BTV-N

FINAL COMMENTS

-BTV, likely are present in other geographic regions outside the Americas and Hawaiian islands.

-Isolates of OFV were found infecting citrus (Mexico, Colombia) and an ornamental in Australia, and similar incidents may have occurred elsewhere, since this virus is distributed worldwide.

-Significant diversity has been found within Cilevirus and Dichorhavirus.