CHARACTERIZATION OF ISOLATES OF THE CUCUMOVIRUS CUCUMBER MOSAIC VIRUS PRESENT IN BRAZIL
M. Eiras, A.J. Boari, A. Colariccio, A.L.R. Chaves, M.R.S. Briones, A.R. Figueira, R. Harakava
Cucumber mosaic virus (CMV) is a naturally occurring virus that infects several crops in Brazil, although its economic and epidemiological impact has not been fully characterized. Samples of different host plant species from different regions of Brazil, including passion- fruit, sweet-pepper, black-pepper, Peperomia, melon, squash, tomato, pea, water-cress, zingiber, banana and Commelina sp., showing foliar symptoms of mosaic, deformations and chlorotic ringspots that resemble those induced by CMV, were collected for biological, serological and molecular analysis. DAS-ELISA, RTPCR/ RFLP, sequencing and phylogenetic analysis were used to characterize the isolates. Nicotiana glutinosa plants, that showed foliar mosaic after inoculation with extracts from the samples collected, were submitted to DAS-ELISA and total RNA extraction. RT-PCR, with specific primers for the 3’ end of RNA 3 and part of the coat protein gene, yielded 486-499 base pair DNA fragments that were characterized by RFLP. ELISA and RTPCR/ RFLP results showed the isolates belong to CMV subgroup I. These results were confirmed by the sequences of the RT-PCR products, which were 92 to 99% identical to those of subgroup I CMV isolates. The multiple sequence alignment of the nucleotides and the translated amino acid sequences of these and other CMV strains, and phylogenetic analyses revealed three distinct clusters. Most of the Brazilian CMV isolates were closely related among themselves and clustered with other CMV subgroup IA isolates. One CMV isolate clustered together with CMV subgroup IB isolates. These results indicate the prevalence of the CMV subgroup I in Brazil.