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Since 1948, pale yellow wheat spike have been reported in southern Brazil. This symptom was associated with tenuiviruses due to the observation of cytoplasmic inclusions constituted by a mass of filamentous particles (7–10 nm in diameter) with indeterminate length, identical to those found in "leaf dip" preparations. Such symptoms are still seen in wheat crops; however, there is a lack of information regarding this pathosystem. Decades after the first report, the first sequences of wheat white spike virus were characterized. Wheat plants with symptoms such as pale yellowing, chlorotic streaks, and leaf mosaic were collected in Paraná State, Southern Brazil. High-throughput sequencing was used to determine the nearly complete nucleotide sequence of the viral genome. The genome is composed of five RNAs with a total size of 18,129 nucleotides, with eight open reading frames (ORFs). The virus identified in this study can be included in a new species in the family Phenuiviridae, genus Tenuivirus, and we have tentatively named this virus "wheat white spike virus". [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is an important food crop for humanity, being cultivated in tropical and temperate regions of the world. This study reports the nearly complete genome sequences of four Brazilian rice stripe necrosis virus (RSNV) isolates. The nucleotide sequences of the RNA1 and RNA2 genome segments of these Brazilian isolates were 96.5 to 99.9% identical, indicating their close phylogenetic relationship to each other. Phylogeny and recombination analysis indicated that the genome of one of the isolates consisted of RNA segments of different origins, suggesting that a reassortment event had occurred. [ABSTRACT FROM AUTHOR]

Soil-borne wheat mosaic disease (SBWMD) caused by wheat stripe mosaic virus (WhSMV) is one of the most important viral diseases of wheat in Brazil. Farmers have used crop rotation (CR) successfully to reduce the incidence of many diseases in wheat. CR can contribute along with genetic resistance in the management of SBWMD. The objective of this study was to evaluate the effect of CR in SBWMD incidence and wheat yield as compared with wheat monoculture (W). During 2017 and 2018 growth seasons, in a long-term experiment, W and three CR: W1 – white oats-wheat; W2 – vetch-white oats- wheat; and W3 – black oats-barley-black oats-wheat were evaluated using three wheat cultivars: BRS Parrudo (resistant), BRS Reponte (moderately resistant) and BRS Guamirim (susceptible). The rainiest season (2018) was more favorable to the development of the disease. In this year, CR W2 and W3 significantly decreased SBWMD incidence by 90% compared to wheat monoculture. Also, grain yield (GY) differences between CR were higher in the rainiest season. GY increases up to 58% (BRS Reponte), 81% (BRS Guamirim) and 106% (BRS Parrudo) in W2 and W3. The use of plant species that are non-hosts of WhSMV may be one of the main factors that contribute to the reduction of SBWMD levels. [ABSTRACT FROM AUTHOR]