RESUMO
Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) are the two Solanaceae-infecting Crinivirus species (family Closteroviridae) of worldwide importance. In Brazil, only ToCV has been detected under natural conditions infecting tomato (Solanum lycopersicum), sweet pepper (Capsicum annuum), and potato (S. tuberosum), causing foliar chlorosis (1, 3). However, there are no formal reports of alternative weed hosts of ToCV. During crop surveys in Capão Bonito, São Paulo State, Brazil (May 2011), a high incidence (above 20%) of plants of the weed, cut leaf ground cherry (Physalis angulata L.) growing around and within a tomato (cv. Alambra) field with a high incidence of ToCV, were found displaying interveinal chlorosis on the lower leaves, similar to those induced by magnesium deficiency. The P. angulata plants also had high populations of whiteflies (Bemisia tabaci biotype B). Ten leaf samples were taken from individual symptomatic ground cherry and tomato plants for Crinivirus testing. Total nucleic acids were extracted from 2 g of symptomatic and healthy leaf tissues of both hosts using Whatman CF-11 cellulose (Sigma) as described (4). The purified double stranded RNA samples were used as a template in reverse transcription (RT)-PCR using specific primers targeting the p22 gene region in the genome of ToCV (2). Only the 566-bp ToCV-specific amplicon was detected in all field samples. Sequences of samples from the P. angulata and tomato cDNA amplicons were identical to each other (GenBank Accession No. JX187514) and they showed 99% identity with the ToCV RNA 1 from a tomato isolate from Florida (AY903447). This confirmed the initial hypothesis of Crinivirus infection. Cuttings of symptomatic P. angulata plants were also obtained and kept in a voile cage under greenhouse conditions together with healthy seedlings of P. angulata and the begomovirus-resistant inbred tomato line 'TX-468RG.' Fifty aviruliferous B. tabaci (biotype B) adults were placed in the cage. Similar symptoms were observed 50 days after exposure to whiteflies in both hosts. Transmission to P. angulata and to 'TX-468RG' was also confirmed via sequencing of ToCV-specific amplicon, demonstrating the infectivity of the isolate to both hosts. To our knowledge, this is the first report of P. angulata as a natural host of ToCV in Brazil. This weed is often present in the commercial fields because of its natural tolerance to herbicides currently used in tomato production. The ToCV-infected P. angulata plants might serve as alternative sources of inoculum for the surrounding tomato fields. The environmental persistence of P. angulata combined with its intense whitefly colonization might allow a year-round ToCV exposure for tomato plants under field conditions in this major production area of Brazil where at least 25 million tomato plants are cultivated annually. References: (1) J. C. Barbosa et al. Trop. Plant Pathol. 36: 256, 2011. (2) M. I. Font et al. Plant Dis. 86:696, 2002. (3) D. M. S. Freitas et al. Plant Dis. 96:593, 2012. (4) R. A. Valverde et al. Plant Dis. 74:285, 1990.
RESUMO
Fruit rots caused by distinct fungal pathogens are commonly observed on tomatoes (Solanum lycopersicum L.) throughout all major production areas in Brazil. Samples of fruits displaying white mycelial growth associated with a profuse salmon-color sporulation were collected in greenhouse-grown tomatoes in Brasília-DF in February 2011. The isolated fungus displayed pink-to-white colonies containing several conidiophores with conidia. Mycelia displayed hyaline hyphae as much as 4 µm in diameter; conidiophores were simple or branched, 112 to 300 (360) µm long, and 2 to 4 µm wide. Conidia were produced in basipetal chains (frequently clustered), were ellipsoidal to pyriform with oblique and prominent truncate basal scars, two-celled, hyaline, and (14-) 16 to 26 (-28) × (6-) 7 to 10 (-12) µm. These characteristics allocated the specimen to Trichothecium roseum (Pers.). Koch's postulates were fulfilled for one fungal isolate by either spraying 10 intact fruits or by placing a drop of a spore suspension (adjusted to 105 conidia/ml) into three to five wounds created on 10 mature fruits of each of two tomato cultivars (Santa Clara and Dominador) by puncturing each fruit with a sterile needle. Five fruits of each cultivar were treated with sterile water as the mock-inoculated control treatment. Identical symptoms to those of the original fruit were observed only in the T. roseum-inoculated samples 5 to 7 days after using both inoculation procedures. Total DNA was extracted from a pure colony of the fungus growing on potato dextrose agar medium and used as template in PCR assays with the internal transcribed spacer (ITS)-4 (5'-TCCTCCGCTTATTGATATGC-3') and ITS-5 (5'-GGAAGTAAAAGTCGTAACAAGG-3') primer pair (2). A single amplicon of approximately 630 bp was observed and directly sequenced. Sequence analysis of the Brazilian isolate (GenBank No. JN081877) indicated identity levels of 99% with T. roseum isolates reported on Leucadendron xanthoconus in South Africa (GenBank No. EU552162) and isolates from strawberry fruits in South Korea (GenBank No. HM355750). However, phylogenetic analysis was unable to discriminate isolates of T. roseum from Passalora (GenBank No. EF432764) and Fusarium (GenBank No. GU183369) isolates, confirming the low genetic variability of the ITS region in Hypocreales (3). T. roseum has been reported to be infecting greenhouse tomatoes in the United States (4) and causing postharvest disease of tomatoes in Argentina (1). To our knowledge, this is the first report of T. roseum infecting greenhouse tomatoes in Brazil. References: (1) G. Dal Bello. Australas. Plant Dis. Notes 3:103, 2008. (2) N. L. Glass and G. C. Donaldson. Appl. Environ. Microbiol. 61:1323, 1995. (3) L. Lombard et al. Stud. Mycol. 66:31, 2010. (4) A. W. Welch, Jr. et al. Plant Dis. Rep. 59:255, 1975.
RESUMO
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.
RESUMO
A new ascomycete genus placed in family Capnodiaceae found in the Brazilian Cerrado is described and designated Plurispermiopsis, type species P. cerradensis.
Assuntos
Ascomicetos/genética , Ascomicetos/classificação , Ascomicetos/isolamento & purificação , Ascomicetos/ultraestrutura , Brasil , Cor , Ecossistema , FilogeniaRESUMO
The cutaneous leucocyte-associated antigen receptor (CLA) can direct Leishmania-specific T lymphocytes towards inflamed skin lesions. Homing receptors [CLA, lymphocyte-associated antigen 1 (LFA-1) or CD62L] were analysed in lymphocytes from blood and cutaneous leishmaniasis (CL) lesions. CL patients with active lesions (A-CL) presented lower levels of T lymphocytes expressing the CLA(+) phenotype (T CD4(+) = 10.4% +/- 7.5% and T CD8(+) = 5.8% +/- 3.4%) than did healthy subjects (HS) (T CD4(+) = 19.3% +/- 13.1% and T CD8(+) = 21.6% +/- 8.8%), notably in T CD8(+) (P < 0.001). In clinically cured patients these percentages returned to levels observed in HS. Leishmanial antigens up-regulated CLA in T cells (CLA(+) in T CD4(+) = 33.3% +/- 14.1%; CLA(+) in T CD8(+) = 22.4% +/- 9.4%) from A-CL but not from HS. An enrichment of CLA(+) cells was observed in lesions (CLA(+) in T CD4(+) = 45.9% +/- 22.5%; CLA(+) in T CD8(+) = 46.4% +/- 16.1%) in comparison with blood (CLA(+) in T CD4(+) = 10.4% +/- 7.5%; CLA(+) in T CD8(+) = 5.8% +/- 3.4%). Conversely, LFA-1 was highly expressed in CD8(+) T cells and augmented in CD4(+) T from peripheral blood of A-CL patients. In contrast, CD62L was not affected. These results suggest that Leishmania antigens can modulate molecules responsible for migration to skin lesions, potentially influencing the cell composition of inflammatory infiltrate of leishmaniasis or even the severity of the disease.