Caracterização molecular de dois isolados de Rice stripe necrosis virus

• Autor(a) principal: Souza, Daniela Domingos de
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/11327
• topic: RSNV; Polymyxa graminis; Oryza sativa; HTS; Arroz tropical; Polymyxa graminis; Oryza sativa; HTS; Tropical rice; RSNV; CIENCIAS AGRARIAS::AGRONOMIA

Rice stripe necrosis virus (RSNV) is a benyvirus transmitted by the plasmodioforomycete Polymyxa graminis Ledingham that causes the disease known as rice crinkling. RSNV genome is composed of two single-stranded, polyadenylated, and positive-sense RNA segments that are individually encapsulated in rod-shaped particles. The reemergence of the virus in Africa and South America as well its recent spread beyond the southern region of Brazil indicates the need to understand its genetic variability in order to generate information to assist in the diagnosis and control of the virus. Thus, the objectives of this work were to molecularly characterize two isolates of RSNV obtained from rice in the state of Goiás and to analyze the genetic variability of this virus. For this purpose, samples of two symptomatic plants, collected in experiments at Embrapa Arroz e Feijão in Goianira and Santo Antônio de Goiás, GO, were subjected to total RNA extraction, enrichment of dsRNA, and high-performance sequencing (HTS), resulting in 27 and 66 million reads for each sample. After assembling with Tadpole software, ten contigs were obtained, corresponding to two viral genomes, each composed of two RNA segments (RNA1 and RNA2). The genomic organization and genome size of the studied isolates were similar to those of the other six previously characterized RSNV isolates. The amino acid sequences of the capsid protein of the two isolates showed an identity greater than 95% with other RSNV sequences, and the general identity of the nucleotide sequences of RNA1 and RNA2 was equal to or greater than 95%. Analyzes performed with the RDP4 software program did not detect recombination events in the studied isolates. Phylogenetic trees based on the complete sequences of RNA1 and RNA2 and the coding region of the helicase motif revealed a close phylogenetic relationship between RSNV isolates characterized in this work and those previously characterized and indicated a cluster pattern according to the geographic origin of the isolates. These results collaborate to broaden the understanding of the molecular diversity of RSNV isolates and, thus, contribute to their control.