ABSTRACT: Severe mosaic symptoms, accompanied by yellow spots, abnormally small leaves, fruit malformation and cracking, reduced plant growth, and high levels of whitefly (Bemisia tabaci MEAM1) infestation were observed in passionflower (Passiflora edulis) orchards in southwestern Bahia, Brazil. The aim of this work was to identify the species of begomovirus infecting the passionflowers, its prevalence in southwestern Bahia, and the spatial and temporal dynamics of the disease. Leaf samples from symptomatic plants collected at 57 orchards located in ten counties were evaluated by PCR for begomovirus infection. Complete nucleotide sequences of DNA-A for two isolates revealed 97 % identity with Passionfruit severe leaf distortion virus (PSLDV). The occurrence of PSLDV in 57 orchards was evaluated based on the presence of characteristic disease symptoms. Approximately 235,000 visually assessed plants exhibited symptoms characteristic of begomovirus infection. Epidemiological studies, conducted in two orchards in Dom Basílio County, showed that disease progress was relatively slow until 121 days after transplanting (DAT), but more rapid in the following 35 days, reaching 100 % infected plants by 156 DAT. The exponential model was fitted to the temporal dynamic of the disease for both areas. An aggregated pattern of diseased plants was predominant for almost all evaluations. It is possible that the primary and secondary spread of the pathogen occurred concurrently during the epidemic progression in both areas, especially late in the season. Containment measures to prevent the virus and the vector from spreading to other passionfruit producing areas in Brazil should be implemented.

RESUMO A alface (Lactuca sativa L.) pertencente à família Asteraceae e é uma das hortaliças mais consumidas no Brasil. O Lettuce mosaic virus (LMV) é um dos vírus mais importantes da cultura e, atualmente, a principal forma de controle é a utilização de genótipos portadores do gene de tolerância mol1 e mo12. Um isolado de LMV proveniente de Botucatu (SP), denominado LMV-Bot, foi identificado quanto as suas características biológicas e moleculares. Ao ser inoculado nas variedades de alface diferenciadoras de patótipos de LMV em alface (‘Ithaca - gene Mo’, ‘Malika - mo11’, ‘Vanguard 75 – Mo e mo12’ e ‘Salinas 88 - mo12’), o LMV-Bot induziu sintomas somente em ‘Salinas 88’. A porção N’ terminal que codifica a proteína capsidial foi amplificada, sequenciada e seu posicionamento filogenético revelou similaridade com dois isolados brasileiros denominados Br6 e A435 e também com um coletado na França (Fr4). Porém, o LMV-Bot não se enquadrou no sub-grupo Most e Common. Os resultados sugerem que apesar de raros, isolados atípicos de LMV são encontrados na natureza infectando alface, e podem contornar o gene de resistência mol2.

ABSTRACT Lettuce (Lactuca sativa L.) belongs to the Asteraceae family and is one of the most consumed vegetables in Brazil. Lettuce mosaic virus (LMV) an important virus for this crop and, currently, its main control form is based on the utilization of genotypes carrying the tolerance gene mol1 and mol2. A LMV isolate from Botucatu (SP), named LMV-Bot, was identified considering its biological and molecular characteristics. When inoculated in distinctive lettuce varieties that classifies LMV pathotypes (‘Ithaca - Mo gene’, ‘Malika – mol1’ ‘Vanguard 75 - Mo and mol2’ and ‘Salinas 88 - mo12’), LMV-Bot induced symptoms only in ‘Salinas 88’. The N’ terminal coding region for the capsid protein was amplified and sequenced, and its phylogenetic position revealed similarity to two Brazilian isolates named BR6 and A435 and to another one from France (FR4). However, LMV-Bot did not fit in the sub-group Most and Common. Results suggest that, although rare, atypical isolates of LMV are found in nature infecting lettuce and can break the resistance gene mol2.

Resumo: O objetivo deste trabalho foi avaliar o efeito da aplicação de fungicidas na concentração de Tomato severe rugose virus (ToSRV, Begomovirus) no híbrido de tomateiro 'Mariana' coinfectado por ToSRV e Tomato chlorosis virus (ToCV, Crinivirus) e a progressão da concentração viral por qPCR, bem como quantificar a produção e a qualidade de frutos. O experimento I consistiu na aplicação dos fungicidas após a semeadura (pré-tratamento): piraclostrobina+metiram (P+M) (a 3 g L-1) + boscalida (B) (a 0,3 g L-1), seguida de pulverizações quinzenais com P+M (4 g L-1); no experimento II, não houve aplicação na semeadura (controle), apenas 4 g L-1 de P+M quinzenalmente. As transmissões de ToSRV e ToCV foram realizadas com uso de moscas-brancas (Bemisia tabaci, biótipo B), aos 15, 30, 45, 60 e 70 dias após o transplante (DAT). Houve aumento da produção, melhor qualidade dos frutos e redução da concentração de ToSRV nas plantas, quando os vírus foram transmitidos tardiamente e o pré-tratamento foi realizado. O pré-tratamento na bandeja, na semeadura, com P+M (3 g L-1) e B (0,3 g L-1), seguido de pulverizações quinzenais com P+M (4 g L-1), aumenta a produção e a qualidade dos frutos, em tomateiro híbrido 'Mariana' coinfectado aos 45, 60 e 75 DAT por ToSRV e ToCV, e há redução da concentração de ToSRV.

Abstract: The objective of this work was to evaluate the effect of fungicide application on the concentration of Tomato severe rugose virus (ToSRV, Begomovirus) in the 'Mariana' hybrid tomato coinfected with ToSRV and Tomato chlorosis virus (ToCV, Crinivirus) and the progression of viral concentration by qPCR, as well as to quantify fruit yield and quality. Experiment I consisted in the application of fungicides after sowing (pretreatment): pyraclostrobin+metiram (P+M) (at 3 g L-1) + boscalid (B) (at 0.3 g L-1), followed by biweekly sprayings with P+M (4 g L-1); in experiment II, there was no application at sowing (control treatment), only 4 g L-1 P+M biweekly. ToSRV and ToCV transmissions were performed using sweetpotato whiteflies (Bemisia tabaci, biotype B), at 15, 30, 45, 60, and 70 days after transplanting (DAT). There was an increase in yield, better fruit quality, and a reduction in the ToSRV concentration in the plants, when the viruses were transmitted late and pretreatment was performed. Tray pretreatment in sowing with P+M (3 g L-1) and B (0.3 g L-1), followed by biweekly sprayings with P+M (4 g L-1), increases fruit yield and quality in the 'Mariana' hybrid tomato coinfected at 45, 60, and 75 DAT by ToSRV and ToCV, and there is a reduction in the concentration of ToSRV.

A necrose da haste em soja é causada pelo vírus Cowpea mild mottle virus (CPMMV) e é considerada uma doença emergente e economicamente importante no Brasil. Apenas cultivares tolerantes foram identificadas até o momento, e o controle genético da tolerância permanece desconhecido. Para estudar a herança da tolerância ao CPMMV foram realizados dois cruzamentos para obter as gerações F2 e F2:3, um entre duas cultivares tolerantes (BRS 133 x BRSMT Pintado) e outro entre uma cultivar suscetível (CD 206) e outra tolerante (BRSMT Pintado). Análises qualitativas e quantitativas aplicadas sobre os dados obtidos nas avaliações em casa-de-vegetação mostraram que existem pelo menos dois genes maiores distintos, um na cultivar de soja BRS 133 e outro na cultivar BRSMT Pintado, determinando a tolerância ao CPMMV. Houve predominância de efeitos genéticos aditivos e herdabilidade, que permite a seleção eficiente baseada em médias, mesmo nas primeiras gerações após o cruzamento.

Soybean stem necrosis is caused by Cowpea mild mottle virus (CPMMV) and it has been recognized as an emerging and economically important disease in Brazil. No resistant, but only tolerant cultivars have been identified so far, and their genetic control is still unknown. To investigate the inheritance of soybean tolerance to CPMMV, two crosses between tolerant cultivars (BRS 133 x BRSMT Pintado), and between a susceptible (CD 206) and a tolerant cultivar (BRSMT Pintado) were carried out to obtain F2 and F2:3generations. Quantitative and qualitative analyses applied to the data from greenhouse evaluations showed that there are at least two distinct major genes determining tolerance to CPMMV, one in the soybean cultivar BRS 133 and another in the cultivar BRSMT Pintado, with predominance of additive genetic effects and heritability levels that allow for efficient selection based on early generation means.

Garlic (Allium sativumL.) is a host to several viruses, most commonly those belonging to theAllexivirus,Carlavirus, orPotyvirusgenera. Nine species distributed among these three genera have been reported in Brazil: two species within carlaviruses, two within potyviruses, and five within allexiviruses. To quantify the prevalence of these viruses, young leaves from 520 plants (plants either symptomatic or asymptomatic) were collected from commercial fields grown in four Brazilian states and analyzed using universal and species-specific primers via the reverse transcription polymerase chain reaction (RT-PCR). Potyvirus presence was positive in 306 samples (81 %), 151 of them (38 %) in mixed infections with other viruses. The most frequent potyviruses wereOnion yellow dwarf virus(OYDV, 56 %) andLeek yellow stripe virus(LYSV, 55 %). 187 samples (49 %) were positive for allexivirus, with 33 (9 %) showing single infections and 154 (41 %) showing mixed infections withGarlic virus A (GarV-A),Garlic virus B(GarV-B),Garlic virus C(GarV-C),Garlic virus D(GarV-D), and species belonging to theCarlavirus andPotyvirusgenera. The predominant species in which allexiviruses were found were GarV-A and GarV-D. Only 15 samples (4 %) were infected solely by a carlavirus, and 63 (17 %) showed mixed infections with viruses from different genera. The dominant species of carlavirus wasGarlic commom latent virus(GarCLV). Carlaviruses and allexiviruses are frequently associated with mixed infections with potyviruses, whereas mixed infections with carlaviruses and allexiviruses are rare. About 70 % of the plants collected were positive for at least one species of virus.

Em campos de produção comercial de alho é comum observar plantas naturalmente infectadas por vírus dos gêneros Allexivirus, Carlavirus e Potyvirus. Os bulbilhos aéreos podem ser uma alternativa para a propagação de plantas de alho livres de vírus. Desta forma, o objetivo deste trabalho foi analisar a taxa de perpetuação dos vírus de plantas infectadas para os bulbilhos aéreos. Os bulbilhos aéreos obtidos de plantas infectadas foram analisados por RT-PCR utilizando oligonucleotídeos universais para os gêneros Allexivirus, Carlavirus e Potyvirus. A taxa de perpetuação foi de 65% para allexivírus, 20% para carlavírus e 82,22% para potyvírus. Os resultados demonstraram que a perpetuação dos diferentes vírus do bulbo para os bulbilhos aéreos é elevada, inviabilizando a utilização direta dos bulbilhos aéreos provenientes de plantas matrizes infectadas por vírus. Esta metodologia deve ser utilizada somente a partir de plantas isentas de vírus.

In commercial garlic fields, plants naturally infected by viruses of the genera Allexivirus, Carlavirus and Potyvirus are commonly observed. Aerial bulbils may be an alternative for the propagation of virus-free garlic plants. Thus, the aim of this study was to analyze the rate of virus perpetuation from infected plants to aerial bulbils. Aerial bulbils obtained from infected plants were analyzed by RT-PCR using universal primers for the genera Allexivirus, Carlavirus and Potyvirus. Results showed that the perpetuation of different viruses from the bulb to aerial bulbils is high, impairing the direct use of aerial bulbils from virus-infected matrix plants. This methodology should use solely virus-free plants.

Garlic plants are naturally infected by a mixture of viruses, including allexiviruses. Symptomatic garlic plants with mosaic and distorted leaves from garlic producing regions in Brazil were analyzed for the presence of Garlic virus A (GarV-A), Garlic virus B (GarV-B), Garlic virus C (GarV-C), Garlic virus D (GarV-D) and Garlic mite-borne filamentous virus (GarMbFV), five allexivirus species previously reported in the country. Fifty-nine virus isolates from five distinct allexivirus species were identified and the complete coat protein region of each genome was sequenced. Mixed infections were very frequent and corresponded to 43% of the positive samples. The nucleotide identity of the coat protein ranged between 75% and 98% for GarV-A isolates, 83% and 90% for GarV-B, 69% and 98% for GarV-C, 87% and 97% for GarV-D, and 72% and 91% for GarMbFV.

As plantas daninhas podem atuar como importantes reservatórios de vírus. Solanum americanum (Maria Pretinha) é uma planta daninha comum no Brasil e amostras com mosaico foram coletadas em áreas produtoras de pimentão, para verificar a presença de vírus. Uma amostra apresentou infecção mista com Cucumber mosaic virus (CMV) e Potato virus Y (PVY) e uma amostra apresentou infecção simples com PVY. As duas espécies virais foram transmitidas por extrato vegetal e ocasionaram mosaico em tomate (Solanum lycopersicum cv. Santa Clara), pimentão (Capsicum annuum cv. Magda), Nicotiana benthamiana e N. tabaccum TNN, lesões locais em Chenopodium quinoa, C. murale e C. amaranticolor. As sequências de proteína capsidial para o CMV e PVY encontradas em S. americanum estão filogeneticamente mais relacionadas com isolados de tomate. Conclui-se que S. americanum pode atuar como reservatório de diferentes vírus, durante e entre as épocas de cultivo de pimentão.

Weeds can act as important reservoirs for viruses. Solanum americanum (Black nightshade) is a common weed in Brazil and samples showing mosaic were collected from sweet pepper crops to verify the presence of viruses. One sample showed mixed infection between Cucumber mosaic virus (CMV) and Potato virus Y (PVY) and one sample showed simple infection by PVY. Both virus species were transmitted by plant extract and caused mosaic in tomato (Solanum lycopersicum cv. Santa Clara), sweet pepper (Capsicum annuum cv. Magda), Nicotiana benthamiana and N. tabaccum TNN, and local lesions on Chenopodium quinoa, C. murale and C. amaranticolor. The coat protein sequences for CMV and PVY found in S. americanum are phylogenetically more related to isolates from tomato. We conclude that S. americanum can act as a reservoir for different viruses during and between sweet pepper crop seasons.

Tomato severe rugose virus (ToSRV) is the predominant species of begomovirus in São Paulo State, Brazil, and infects primarily tomato and pepper plants. There is no information about genetic resistance of pepper to this virus, so in this work the reaction of 29 genotypes of Capsicum spp. was evaluated by inoculation of two ToSRV isolates: ToSRV-Sk (isolated from a tomato plant) and ToSRV-PJU (isolated from a pepper plant). For both isolates, two C. annuun genotypes (Catarino Cascabel - México and Silver) showed no symptoms 30 days after inoculation (d.a.i). In a second experiment, these two genotypes were evaluated for 150 d.a.i and, again, no symptoms could be observed. However, the virus was detected by RCA-PCR, indicating that both genotypes are susceptible, but less affected by ToSRV infection. Catarino Cascabel - México and Silver can be indicated for use in breeding programs for resistance of pepper to ToSRV.

O Potato virus Y (PVY) e Pepper yellow mosaic virus (PepYMV) são as únicas espécies de potyvirus encontradas em pimenta e pimentão no Brasil. A região codificadora para a proteína capsidial de isolados de PepYMV e PVY coletados em pimentão, foi avaliada quanto à variabilidade e presença de motivos específicos aos potyvirus. A identidade da seqüência de aminoácidos na CP entre os isolados de PepYMV foi de 93% a 100%, enquanto que para os de PVY 94% a 98%. Entre os vírus esta variou de 73% a 79%. Foi observada variabilidade nas regiões conservadas da CP. Todos os isolados de PepYMV seqüenciados não apresentaram o motivo DAG na CP, relacionada a transmissão dos vírus por afídeos, enquanto que para as seqüências obtidas de PVY foi observada. Demais domínios como MVWCIENG, ENTERH, QMKAAA e PYMPRYG foram verificadas em ambas espécies.

Potato virus Y (PVY) and Pepper yellow mosaic virus (PepYMV) are the only potyvirus species found in pepper and sweetpepper in Brazil. The region encoding the coat protein of PVY and PepYMV isolates collected in sweetpepper was evaluated for the presence of specific motifs of potyviruses. The identity of the amino acid sequence in CP among PepYMV isolates was 93% to 100%, while for PVY was 94% to 98%. Among the viruses that ranged from 73% to 79%. It was observed variability in the conserved regions of the CP. All PepYMV isolates sequenced did not show the DAG motif in the CP, related to virus transmission by aphids, while for sequences of PVY this motif was observed. Other motifs, such MVWCIENG, ENTERH, QMKAAA and PYMPRYG were found in both species.