Banana streak virus (BSV) and Cucumber mosaic virus (CMV) are commonly found in all banana growing-areas of the world. These viruses cause diseases that lead to yield reduction and constrain plant breeding and distribution of Musa germplasm. Most of the diagnostic methods targeting BSV can generate dubious results because of the considerable genetic and serological diversity among BSV isolates and the presence of integrated BSV sequences in the banana plant. Both viruses are usually detected in single and mixed infections in banana plantations in the north region of Paraná state using DAS-ELISA and PCR. A rolling-circle amplification protocol tested in this study allowed specific detection and identification of an episomal BSV isolate infecting Nanicão Jangada cultivar, thus confirming the occurrence of Banana streak OL virus in Brazil.

Em um levantamento conduzido na região noroeste do Paraná, principal região produtora de mandioca do estado, constatou-se que o CsCMV está amplamente disseminado, infectando mais de 90% das plantas de todas as cultivares. Um isolado do CsCMV foi purificado para a produção de um anti-soro policlonal de alto título (1/1000), o qual foi utilizado na indexação por meio de PTA-ELISA de plantas produzidas via cultura de meristemas. De uma produção inicial de 110 plantas da cultivar Olho Junto, 31 permaneceram infectadas como indicou o PTA-ELISA. Visando aumentar a sensibilidade de detecção do vírus, foi estabelecido um protocolo de IC-RT-PCR. A IgG purificada, específica para o vírus, combinada com um par de oligonucleotídeos universais para Potexvirus, prontamente detectou o CsCMV nos extratos obtidos de mandioca. Produtos de IC-RT-PCR de 750 pb foram amplificados a partir de seis de um total de 35 plantas previamente testadas como negativas para o CsCMV via PTA-ELISA. Os sequenciamentos confirmaram que os produtos de IC-RT-PCR são parte do gene codificador da replicase do CsCMV, indicando assim a presença do vírus mesmo após a termoterapia combinada com a cultura de meristemas. O PTA-ELISA permitiu a triagem preliminar de plantas vírus-positivas, possibilitando a redução do número de plantas a serem analisadas por IC-RT-PCR. Embora o CsCMV seja considerado de importância menor, o fato desse vírus estar disseminado na região noroeste do Paraná recomenda a adoção de medidas efetivas para o seu controle.

A virus survey conducted in the northwest region of Paraná, the main cassava-producing region of that state, showed Cassava common mosaic virus (CsCMV) to be widespread, infecting more than 90% of plants from all cassava cultivars. A CsCMV isolate was purified and used to raise a high-titer (1/1.000) polyclonal antiserum for indexing plants produced from meristem-tip culture, using PTA-ELISA. From an initial production of 110 plants of cultivar Olho Junto, 31 remained infected as indicated by PTA-ELISA. To improve the sensitivity of virus detection, an immunocapture-RT-PCR (IC-RT-PCR) protocol was established. Virus-specific IgG, purified and combined with a primer set for the genus Potexvirus, could readily detect CsCMV in cassava crude leaf extracts. IC-RT-PCR products of 750 bp were amplified from six out of 35 plants previously tested as virus-negative by PTA-ELISA. Sequence analysis of cloned IC-RT-PCR products confirmed they were part of the CsCMV replicase gene, indicating that the virus was still present after thermotherapy and meristem-tip culture. PTA-ELISA enabled initial screening of virus-positive cassava, reducing the number of plants to be further analyzed by IC-RT-PCR. Though CsCMV has been considered of minor importance, its widespread nature, as noticed in Paraná, indicates the need for adoption of effective control measures.