ISHS Acta Horticulturae 781: XX International Symposium on Virus and Virus-Like Diseases of Temperate Fruit Crops - Fruit Tree Diseases
GENOMIC DIVERSITY OF CHERRY CAPILLOVIRUS A (CVA) AND SUITABILITY OF VARIOUS ASSAYS FOR ITS DETECTION |
| Authors: | A. Marais, L. Svanella-Dumas, T. Candresse, M. Barone, A. Ragozzino, P. Gentit |
| Keywords: | filamentous virus, etiology, Capilloviruses, variability, sweet cherry tree decline disease |
| Abstract:
Cherry virus A (CVA) is a poorly known member of the Capillovirus genus whose potential association to a new decline disease of sweet cherry described from Southern France was recently questioned. The PDO nested RT-PCR was used as a detection tool to look for Trichoviruses, Capilloviruses and Foveaviruses in symptomatic and asymptomatic cherry samples (Foissac et al., 2005). The results suggest that there is no association between CVA and the cherry tree decline disease. In parallel, using the short fragment of the viral RNA-dependent RNA polymerase (RdRp) amplified by the PDO nested RT-PCR assay, the diversity of CVA isolates was analyzed. Substantial diversity was observed, with an average pairwise nucleotide divergence between isolates of about 9%. The major group of isolates identified clustered together with the CVA type isolate. Four additional divergent clusters of isolates could be identified, one of which corresponds to isolates obtained from non-cherry (apricot, plum) hosts. The average genetic distance between the various clusters in the sequenced region reached 19%. The polyvalence of the currently available CVA detection techniques was then assessed using a range of isolates representative of the four main phylogenetic clusters. Remarkably, outside of the major phylogenetic cluster, neither molecular hybridisation tests using probes derived from the 5’ end or from the 3’ end of the genome, nor the RT-PCR assay using the CVA1-CVA2 primer pair (James and Jelkmann, 1998) permitted the detection of all the CVA isolates. These results provide evidence for a previously unrecognized genetic diversity in CVA and indicate that new, more polyvalent assays are needed for the efficient detection of all isolates of this virus. | |
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