Molecular characterization of the complexity in banana bunchy top virus genome. [P.57]

Rajeswaran Rajendran, Guyot Valentin, Laboureau Nathalie, Galzi Serge, Caruana Marie-Line, Pooggin Mikhail. 2019. Molecular characterization of the complexity in banana bunchy top virus genome. [P.57]. In : Livre des résumés des 17 ème Rencontres de virologie végétale. INRA, CIRAD, CNRS, SFP, SFV. Aussois : INRA, Résumé, 116. Rencontres de Virologie Végétale (RVV 2019). 17, Aussois, France, 27 Janvier 2019/31 Janvier 2019.

Résumé : Banana bunchy top virus (BBTV) is the most important viral disease of banana and all the known varieties of banana are susceptible to the banana bunchy top disease (BBTD). BBTV is a multipartite virus with six circular single stranded DNA components (DNA-C, DNA-M, DNA-N, DNA-R, DNA-S and DNA-U3) of ~1 kb in size and are transmitted by banana aphids. Rolling circle amplification (RCA) was used to amplify the BBTV components from BBTV-infected banana plants and viruliferous aphids, RCA products sequenced with Illumina deep sequencing and sequencing reads were de novo assembled to reconstruct the consensus BBTV genome. A single dominant variant of DNA-C, DNA-N and DNA-R components, two variants of DNA-M (M1 and M2) and DNA-S (S1 and S2) and at least five variants of DNA-U3 (U3-1, U3-2, U3-3, U3-4 and U3-5) were obtained to denote the complexity of BBTD. A single dominant variant of a novel alphasatellite was also found to be frequently associated with BBTV and when present, it was way more abundant than the BBTV components.Infectious clones are a prerequisite for molecular characterization of any viral disease and till date there is no report of an infectious clone for BBTV. We have cloned all the BBTV genomic components, including the alphasatellite, constructed partial dimer clones and evaluated the infectivity of these constructs in the host banana plant and the model plant Nicotiana benthamiana by agroinoculation. Preliminary analysis with PCR and immuno-capture PCR showed that Nicotiana benthamiana plants can act as a good model system to study BBTV infection.All the plants employ RNA silencing as a primary mode of defense against viruses and viruses counteract this defense mechanism by expression of a silencing suppression protein(s). To identify the silencing suppressor protein(s) of BBTV, we expressed the open reading frames of all the six BBTV components, cell-cycle link protein, movement protein, nuclear shuttle protein, replication initiator protein, coat protein, a protein of unknown function and the alpha-replicase under a constitutive promoter and screened them for their ability to suppress RNA silencing in the GFP-transgenic Nicotiana benthamiana 16c system. Summary of the complexity in BBTV genome, infectivity of the cloned components, role of the alphasatellite in BBTD, RNA silencing-mediated host defense against BBTV and the ability of BBTV ORFs to suppress RNA silencing will be presented.

Auteurs et affiliations

• Rajeswaran Rajendran, University of Basel (CHE)
• Guyot Valentin, Montpellier SupAgro (FRA)
• Laboureau Nathalie, CIRAD-BIOS-UMR BGPI (FRA) ORCID: 0000-0002-0105-3919
• Galzi Serge, CIRAD-BIOS-UMR BGPI (FRA)
• Caruana Marie-Line, CIRAD-BIOS-UMR BGPI (FRA) ORCID: 0000-0003-4486-2449
• Pooggin Mikhail, INRA (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/591012/)

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