Distinct strains of the re-emergent Cassava common mosaic virus (Genus: Potexvirus) infecting cassava in Argentina

ZANINI, ANDREA; LUQUE, VICENTE; DI FEO, LILIANA DEL VALLE; CELLI, MARCOS; CONCI, VILMA; CUELLAR, WILMER; RICARDO DANIEL MEDINA

PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018 vol. 67 p. 1814 - 1820

0032-0862

Cassava common mosaic disease (CCMD) has been reported in all regions where cassava is grown in the Americas and the causal agent, Cassava common mosaic virus (CsCMV) was identified as a mechanically transmitted potexvirus (Fam. Alphaflexiviridae). In Argentina, cassava is grown mainly in the North East region (NEA) that shares borders with Brazil and Paraguay. Increasing incidences of CCMD were observed during the years 2014 to 2016 associated to severe leaf mosaic symptoms and yield reductions where the occurrence of CsCMV was confirmed by RT-PCR and sequencing. In this work we successfully purify an Argentinean field-isolate of CsCMV and obtain antiserum and develop a double-antibody sandwich ELISA (DAS ELISA) to extend the diagnostics of the disease. A collection of 726 samples was screened and CsCMV was detected with 100% prevalence in the NEA region. Additional co-infecting viruses were detected in some plants (64.4%); in these, CCMD symptoms correlated with CsCMV only, although more severe symptoms could be observed in mixed infected plants. By analyzing a region corresponding to the conserved RdRp domain we show a high diversity of CsCMV isolates present in the samples, some of them grouping with isolates from Colombia, Paraguay, Argentina, Brazil and Peru. Interestingly, a separate cluster was formed by sequences isolates from NEA samples which only share 77.1 to 80.3% nucleotide identity with the other cluster. These results indicated the presence of mixed strains causing CCMD in the NEA region and suggested the occurrence of a newly introduction of CsCMV, likely from other countries or hosts.