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Snap and common beans (Phaseolus vulgaris L.) are severely affected by Bean golden mosaic virus (BGMV) infection, so far the only begomovirus reported on these crops in Brazil (1). Samples of snap and common beans colonized by the whitefly Bemisia tabaci biotype B and displaying golden mosaic, chlorotic spots, and leaf distortion were collected in three production regions in Goiás State (Goianápolis, Luziânia, and Itaberaí) between 2003 and 2007. Total DNA extracted from leaf samples was used as template in PCR assays using universal primers targeting conserved regions of the DNA-A and DNA-B genomes (3). Begomovirus-specific amplicons were observed only with DNA template from symptomatic plants. Two single amplicons were observed for both genomic segments, indicating the presence of bipartite species in all samples. Sequence analysis of four isolates (named as GO-176, GO-260, GO-354, and GO-368) obtained from common bean samples indicated identity levels of approximately 95% with the DNA-A segment of BGMV (GenBank Accession No. FJ665283). However, the complete DNA-A sequence (GenBank Accession No. HM357459.1) of the GO-060 isolate (from a symptomatic snap bean plant collected in Goianápolis) displayed 76% identity with BGMV (GenBank Accession No. FJ665283) and 95% identity with the DNA-A of a Sida micrantha mosaic virus (SimMV) isolate (GenBank Accession No. EU908733.1) reported to be infecting okra (Abelmoschus esculentus L.) and 94.8% with a SimMV isolate reported to be infecting soybean (GenBank Accession No. FJ686693) in Brazil (2). Koch's postulates were fulfilled for the isolate GO-060 by inoculating a set of soybean and bean accessions via a biolistic approach. The ratio of positive PCR amplicons per total of inoculated plants were 15 of 16 for snap bean cv. Trepador, 9 of 10 for snap bean cv. Fartura, 18 of 24 for common bean cv. Olate Pinto, and 19 of 25 for common bean cv. Carioca. The isolate was also able to infect eight of nine soybean ‘Doko’ plants. Sequence analysis using symptomatic leaf samples (15 days after inoculation) confirmed SimMV as the causal agent. To our knowledge, this is the first report of a SimMV isolate infecting P. vulgaris. This virus is apparently fast expanding its host range from Malvaceae to Solanaceae species and leguminous hosts after the introduction of B. tabaci biotype B (2). More extensive surveys are necessary to access the current epidemiological importance of SimMV in both snap and common beans in Brazil. References: (1) J.C. Faria and D. P. Maxwell. Phytopathology 89:262, 1999. (2) F. R. Fernandes et al. Arch. Virol. 154:1567, 2009. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993.

A survey of viral diseases was carried out during 2012 to 2013 in two major tomato (Solanum lycopersicum L.) producing regions in Uruguay (Salto and Canelones). Lower leaves of fruit-bearing plants were observed displaying yellowing and interveinal chlorosis under greenhouse conditions. The symptoms were similar to those associated with magnesium deficiency. However, the chlorosis displayed a tendency to move up affecting medial and apical leaves and prevailed even after supplementary magnesium applications to the soil, indicating potential infection by either Tomato chlorosis virus (ToCV) or Tomato infectious chlorosis virus (TICV) (3). Four leaf samples were collected from two sites in Canelones and 28 samples were collected from distinct commercial fields in Salto. Whiteflies (Bemisia tabaci biotype Q and Trialeurodes vaporariorum) were present in all sampling sites. Total RNA was extracted from symptomatic and healthy (control) plants and used for cDNA preparation with the HS-11/HS-12 primer pair followed by PCR amplification using the same primer pair. The 587-bp amplicon, corresponding to a highly conserved region of the heat shock protein (HSP-70) homolog gene reported in both TICV and ToCV genomes, was observed only in the symptomatic samples. These PCR products were then subjected to nested PCR using the ToCV specific primer pair (ToC-5/ToC-6) and TICV specific primer pair (TIC-3/TIC-4) (1). The expected 463-bp ToCV-specific amplicon was observed in all symptomatic plants but not in the healthy controls. The 223-bp amplicon corresponding to TICV was not observed in any sample, indicating the sole presence of ToCV. The amplicon of one Uruguayan ToCV isolate from Salto (named as CRS03) was purified and directly sequenced (GenBank KC626018). BLAST analysis revealed 99% identity of CRS03 with one Spanish isolate (AF233435.1) (2). Virus-free B. tabaci biotype Q adults were exposed to symptomatic plants infected with the CRS03 isolate for a 24-h period and then cage-confined with 10 healthy tomato plants (line ‘LT17’) for a 48-h period. Symptoms were reproduced in all tested plants after a 65-day period and ToCV infection was confirmed via PCR assays and by sequence analysis of the gel-purified amplicons. This is the first formal report of ToCV infecting tomatoes in Uruguay. Incidence of symptomatic plants in tomato crops varied from 30 to 100%, even under low whitefly pressure. Epidemiological information needs to be generated in order to evaluate the impact of ToCV in the fresh-market tomato yield and quality. References: (1) C. I. Dovas et al. Plant Dis. 86:1345, 2002. (2) G. Lozano et al. Arch. Virol. 151:581, 2006. (3) G. C. Wisler et al. Arch. Virol. 151:409, 2006.

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This finding contributes to understanding the diversity of this pathogen in the region where other hosts occur, such as kiwifruit. Made available in DSpace on 2018-11-01T00:57:01Z (GMT). No. of bitstreams: 1 2018AlvaroPDFirstReport.pdf: 495078 bytes, checksum: 026ef0f7428ac49257bf3cd1d93b3826 (MD5) Previous issue date: 2018-10-31 Disease notes.