Detecção de begomovírus e ipomovírus em batata-doce nos estados de Pernambuco e Paraíba e fontes de resistência a Tomato chlorotic mottle virus e Potato virus Y em berinjela

Abstract

The cultivation of sweet potato [Ipomoea batatas L. (Lam.)] is quite broad in Brazil, being the species present in most parts of the country where the largest producers are: Rio Grande do Sul, Minas Gerais, Paraná, Paraíba e São Paulo. This crop is very important, especially for the low-income population, due to the rusticity of the plant, which is easy to grow with low production cost, besides being a good source of energy and various nutrients. Among the pathogens that affect sweet potato, the viruses are noteworthy, especially some species classified in the genus Potyvirus, Begomovirus and Ipomovirus. This plant is host of a wide range of viral species that often form complexes and act in synergism, enhancing disease and causing considerable reduction in yield. One of the goals of this work was to detect the presence of Begomovirus species and Sweet potato mild mottle virus (SPMMV), of the genus Ipomovirus in 55 samples of sweet potato from Pernambuco and Paraíba, being 28 from commercial fields and 27 from a germplasm bank (GB). For detecting begomovirus, DNA extracted from the 55 samples was submitted to RCA and PCR using primers MA292 and MA293. Amplicons generated from 17 GB samples and three field samples were selected, purified and sequenced. After analysis, it was confirmed the presence of of Sweet potato golden vein associated virus - SPGVaV in five samples from GB and two from field and Sweet potato leaf curl virus - SPLCV in 12 samples from GB and one from field. The SPMMV was detected by the serological test Dot-ELISA using specific antibodies in 24 out of 27 BG samples and 25 out 28 field samples. Another focus species of the present study was the eggplant (Solanum melongena L.), economically important food crop available worldwide with approximately 2 million hectares devoted to its cultivation annually. In Brazil, regarding to virus presence in this plant there are only a few reports for species of the genus Tospovirus. In addition, in eggplant fields, practically, no viral symptoms are observed, indicating a possible occurrence of resistance to virus. Thus, another objective of this study was to evaluate the behavior of eggplant genotypes as a possible source of gene(s) for resistance to virus that normally infect plants of the Solanaceae family. Assays were performed using the species Tomato chlorotic mottle virus - ToCMoV, inoculated by the vector Bemisia tabaci and Potato virus Y by mechanical inoculation. The biological evaluation for the two viral species was undertaken by observing symptoms. The detections of ToCMoV and PVY were done using radioactive probes and by Dot-ELISA, respectively. The genotypes were also evaluated for resistance to the vector. The tested materials were considered promising for use in breeding programs because they remained symptomless and no viral accumulation was observed.