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.

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.

Construction of agroinfectious viral clones usually requires many steps of cloning and sub-cloning and also a binary vector, which makes the process laborious, time-consuming, and frequently susceptible to some degree of plasmid instability. Nowadays, novel methods have been applied to the assembly of infectious viral clones, and here we have applied isothermal, single-step Gibson Assembly (GA) to construct an agroinfectious clone of Bean rugose mosaic virus (BRMV) using a small binary vector. The procedure has drastically reduced the cloning steps, and BRMV could be recovered from agroinfiltrated common bean twenty days after inoculation, indicating that the infectious clone could spread in the plant tissues and efficiently generate a systemic infection. The virus was also recovered from leaves of common bean and soybean cultivars mechanically inoculated with infectious clone two weeks after inoculation, confirming the efficiency of GA cloning procedure to produce the first BRMV agroinfectious clone to bean and soybean.