Maize plants displaying severe mosaic, chlorosis and, in some cases, necrosis were observed in two provinces of Ecuador. Shotgun sequencing of cDNA obtained from double-stranded RNA extracted from symptomatic samples revealed the presence of Sugarcane mosaic virus (SCMV) and Maize chlorotic mottle virus (MCMV), two components of maize lethal necrosis. In 2015, a survey conducted in Los Rios, Manabi and Guayas, major maize production areas in the country, showed that the two viruses were present in a significant number of plants. Mixed infections were detected and associated with severe symptoms. MCMV was also detected in two hybrid seed lots, a significant finding for the epidemiology of the disease in Ecuador. The report of maize lethal necrosis, today the most significant virus disease of maize, in Ecuador is of great concern for producers in the South American continent because of the potential of an epidemic as that observed in east Africa in recent years.

Occurrence of maize lethal necrosis in Ecuador: a disease without boundaries?

J. B. Valente, F. S. Pereira, L. A. Stempkowski, M. Farias, P. Kuhnem, D. Lau, T. V. M. Fajardo, A. Nhani Junior, R. T. Casa, A. Bogo and F. N. da Silva* Crop Production Graduate Program, Santa Catarina State University/UDESC, Lages, SC 88520-000; Biotrigo Gen etica, Passo Fundo, RS 99052-160; Embrapa Trigo, Passo Fundo, RS 99050-970; Embrapa Uva e Vinho, Bento Gonc alves, RS 95701-008; and Embrapa Inform atica Agropecu aria, Campinas, SP 13083-886, Brazil

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A novel putative member of the family Benyviridae is associated with soilborne wheat mosaic disease in Brazil

Wheat streak mosaic virus is a serious threat in wheat-producing countries. In Germany, the virus was first recorded in 2013 near Hoym. The complete sequence of isolate Hoym was obtained and compared to all other known complete WSMV sequences, including newly collected and sequenced isolates from France and Austria. Phylogenetic analysis revealed that the European isolates group together with those from the Middle East to form a separate cluster characterized by a distinct putative P1 protease cleavage site. By means of quantitative reverse transcription polymerase chain reaction, it was shown that RNA of the USA type strain PV57 accumulated to higher levels in infected wheat cv. Alcedo than did RNA of isolate Hoym.

First detection of wheat streak mosaic virus in Germany: molecular and biological characteristics

https://ainfo.cnptia.embrapa.br/digital/bitstream/item/138416/1/ID43551-2016v3p62MethodsX.pdf

Development of methodologies for virus detection in soybean and wheat seeds

The objective of this work was to evaluate the phytosanitary aspect of two accessions of maize ( Zea mays ) seeds from the United States introduced to Brazil, regarding the presence of Wheat mosaic virus (WMoV). Two to three weeks after sowing, symptomatic leaves were tested by Elisa using specific antiserum to WMoV. The reaction was positive, and leaf samples were analyzed by real‑time PCR and amplified PCR products were sequenced. The WMoV isolates had 99 to 100% nucleotide identity with isolates from Australia and the United States. Until now, there is no report of the presence of this virus in Brazil. According to the federal law on plant protection, the plants were burned to avoid the introduction of this exotic pest in the country. The obtained results show WMoV interception in Brazil.

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Interception of Wheat mosaic virus (WMoV) in Brazil in maize seeds from the United States

Wheat streak mosaic virus (WSMV—Potyviridae, Tritimovirus), transmitted by the eriophyid mite Aceria tosichella Keifer (Acari: Eriophyidae), was considered a quarantine pest in South America. Since the first report of virus in Argentina, the vector has been found in Argentina, Uruguay and Brazil. The objective of this work was to determine the occurrence of WSMV in Brazil and characterize isolates from wheat-growing areas. Between 2009 and 2011, a total of 40 samples collected in wheat (Triticum aestivum) growing areas, where the presence of the mite was previously related, were tested by RT-PCR for virus detection. Six isolates of WSMV were obtained and characterized by sequencing. Two of them had their host range determined. The Brazilian WSMV isolates clustered in clade D are closely related to the Argentine isolate Arg2 (FJ348359). As expected, isolates were unable to infect dicotyledons plants. They caused mosaic in Triticum aestivum, Hordeum vulgare, Secale cereale, ×Triticosecale, and Zea mays, and they were also able to infect Avena sativa. The presence of WSMV in wheat-growing areas of the Brazilian state Rio Grande do Sul was confirmed, possibly having been introduced from a common source and/or direct vector bearing virus migration from Argentina.

/pdf/identification-and-characterization-of-wheat-streak-mosaic-65h3ybthfb.pdf

Alan Johnny Carminatti

Papers

Identification and Characterization of Wheat Streak Mosaic Virus Isolates in Wheat-Growing Areas in Brazil