Characterization of isolates of the Cucumber mosaic cucumovirus present in Brazil

Cucumber mosaic virus (CMV) is a naturally occurring virus infecting 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, watercress, 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, RT-PCR/RFLP, sequencing and phylogenetic analysis were used to characterize the isolates. Nicotiana glutinosa plants, showing foliar mosaic after inoculation with extracts from the collected samples, 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 RT-PCR/RFLP results showed that the isolates belong to CMV subgroup I. These results were confirmed by the sequences of RT-PCR products, which were 92 to 99; identical to those of subgroup I CMV isolates. The multiple sequence alignment of 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 [Il Virus del mosaico del cetriolo (CMV) è presente naturalmente e infetta numerose colture in Brasile, sebbene il suo impatto economico ed epidemiologico non sia stato pienamente accertato. Campioni di specie di piante ospiti provenienti da aree diverse del Brasile, frutto della passione, peperone dolce, pepe nero, Peperomia, melone, zucchino, pomodoro, pisello, crescione, zenzero, banano, e Commelina sp., con sintomi fogliari di mosaico, deformazioni e maculature anulari clorotiche simili a quelle indotte da CMV, sono stati sottoposti ad analisi biologiche, sierologiche e molecolari. Per caratterizzare gli isolati sono stati utilizzati DAS-ELISA, RT-PCR/RFLP, sequenziamento e analisi filogenetica. Piante di Nicotiana glutinosa, presentanti sintomi di mosaico fogliare a seguito di inoculazione con estratti dei campioni raccolti, sono state