Variability in indigenous Pakistani tomato lines and worldwide reference collection for Tomato Mosaic Virus (ToMV) and Tomato Yellow Leaf Curl Virus (TYLCV) infection / Variabilidade em linhagens indígenas de tomate do Paquistão e coleção de referência global para infecção por vírus do mosaico do tomateiro (ToMV) e vírus da folha amarela do tomate (TYLCV)

Local and exotic germplasm of tomato remains a major source for genetic improvement. Assessment of such lines for biotic stresses particularly viral diseases are the most important criteria for selection in Pakistan, where Tomato Yellow Leaf Curl Virus (TYLCV) and Tomato Mosaic Virus (ToMV) are the major diseases/viruses. A set of 40 accessions (including indigenous Pakistani lines and exotic germplasm from Europe, the United States, and Asia) were evaluated for their resistance/infection response to ToMV with artificial inoculation under greenhouse conditions. Infection response was quantified through disease scoring and DAS-ELISA test (for ToMV). A subset of 24 lines, was further screened for TYLCV using disease scoring and TAS-ELISA. The tested lines showed significant variability for resistance to ToMV. Only one accession (Acc-17878) was resistant to the ToMV whereas seven accessions i.e. Acc-17890, AVR-261, CLN-312, AVR-321, EUR-333, CLN-352, and CLN-362 expressed resistance to TYLCV. Correlation between phenotypic evaluation was confirmed by the ELISA results in both diseases, although both tools complemented to assess the viral infection status. In future, tomato breeding programs must consider breeding for ToMV and TYLCV resistance (using identified germplasm in our study) so as to deliver virus resistant tomato varieties.

O germoplasma local e exótico do tomate continua sendo uma importante fonte de melhoramento genético. A avaliação de linhagens para estresses bióticos, particularmente as doenças virais, é o critério mais importantes para seleção no Paquistão, onde o vírus da folha amarela do tomate (TYLCV) e o vírus do mosaico do tomateiro (ToMV) são as principais doenças/vírus. Um conjunto de 40 acessos (incluindo linhagens indígenas do Paquistão e germoplasma exótico da Europa, dos Estados Unidos e da Ásia) foi avaliado quanto à resistência/resposta à infecção ao ToMV com inoculação artificial em casa de vegetação. A resposta à infecção foi quantificada por meio de pontuação da doença e de teste DAS-ELISA (para ToMV). Um subconjunto de 24 linhas foi posteriormente rastreado para TYLCV usando pontuação de doença e TAS-ELISA. As linhas testadas apresentaram variabilidade significativa para resistência ao ToMV. Apenas um acesso (Acc-17878) foi resistente ao ToMV, enquanto sete acessos (Acc-17890, AVR-261, CLN-312, AVR-321, EUR-333, CLN-352 e CLN-362) expressaram resistência ao TYLCV. A correlação entre a avaliação fenotípica foi confirmada pelos resultados do ELISA nas duas doenças, embora ambas as ferramentas tenham se complementado para avaliar o estado da infecção viral. No futuro, os programas de melhoramento de tomate devem considerar aperfeiçoamentos para resistência ao ToMV e TYLCV (usando germoplasma identificado em nosso estudo) de modo a fornecer variedades de tomate resistentes a vírus.

Enemigos naturales nativos de mosca blanca (Hemiptera: Aleyrodidae) en el cultivo de ejote francés en Chimaltenango, Guatemala / tive natural enemies of whitefly (Hemiptera: Aleyrodidae) in French bean crop in Chimaltenango, Guatemala

El complejo de mosca blanca (Hemiptera: Aleyrodidae) incluye algunas de las principales plagas del ejote francés (Phaseolus vulgaris L.). Dentro de las cuales, Bemisia tabaci es vector del virus del mosaico dorado que afecta la calidad y rendimiento del cultivo, con pérdidas hasta del 100% y un control difícil debido a la resistencia adquirida por las plagas hacia algunos agroquímicos. El ejote francés ocupa el segundo lugar entre de los productos no tradicionales de exportación de Guatemala. Su manejo agronómico ha sido principalmente a través del control químico, el cual afecta insectos y otros organismos que no son el objetivo del control, tales como: polinizadores, insectos benéficos, humanos y fauna silvestre. Los objetivos del estudio fueron: determinar la presencia de enemigos naturales nativos de la mosca blanca e identificar las especies de mosca blanca presentes en el cultivo del ejote francés en Chimaltenango. Para el estudio se establecieron cuatro parcelas de 300 m², se realizaron muestreos semanales durante dos ciclos del cultivo. En cada parcela se muestrearon cinco sitios y en cada sitio cinco plantas. Las especies de parasitoides nativos encontrados fueron: Encarsia Formosa Gahan, Eretmocerus eremicus Rose y Zolnerowuch y Amitus fuscipennis MacGown y Nebeker, la especie más abundante fue A. fuscipennis. Los depredadores identificados fueron Chrysoperla carnea (Stephens) e Hippodamia convergens Guerin-Meneville. La especie más abundante fue H. convergens. Estas especies podrían ser herramientas valiosas para ser empleadas en programas de control biológico, producciones orgánicas o en programas de manejo integrado de plagas.

The whitefly complex (Hemiptera: Aleyrodidae) includes some of the main pests of the French green bean (Phaseolus vulgaris L.). Among which, Bemisia tabaci is a vector of the golden mosaic virus that affects the quality and yield of the crop, with losses up to 100% and difficult control due to the resistance acquired by pests towards some agrochemicals. The French green bean ranks second among the non-traditional export products of Guatemala. Its agronomic management has been mainly through chemical control, which affects insects and other organisms that are not the objective of the control, such as: pollinators, beneficial insects, humans and wildlife. The objectives of the study were: to determine the presence of natural enemies native to the whitefly and identify the species of whitefly present in the cultivation of the French bean in Chimaltenango. For the study, four 300 m² plots were established, weekly sampling was carried out during two crop cycles. Five sites were sampled on each plot and five plants on each site. The native parasitoid species found were: Encarsia Formosa Gahan, Eretmocerus eremicus Rose and Zolnerowuch and Amitus fuscipennis MacGown and Nebeker, the most abundant species was A. fuscipennis. The predators identified were Chrysoperla carnea (Stephens) and Hippodamia convergens Guerin-Meneville. The most abundant species was H. convergens. These species could be valuable tools to be used in biological control programs, organic productions or in integrated pest management programs.

Occurrence and distribution of Apple mosaic virus on hazelnut cultivars in giresun, Turkey / Ocorrência e distribuição do vírus mosaico da macieira em cultivares de avelã em Giresun, Turquia

Apple mosaic virus (ApMV) is the most important viral pathogen of hazelnut. The Black Sea region is the main hazelnut producing area in Turkey. Hazelnut growing areas from Giresun which are located in the Black Sea region were surveyed for occurrence and distribution of ApMV in 2011-2012. Hazelnut leaf samples were collected randomly from non-symptomatic and symptomatic plants displaying yellow rings and lines, yellow flecking, oak leaf pattern and broad vein banding. Leaves from 229 samples collected in 35 fields were tested for the presence of ApMV using enzyme-linked immunosorbent assay (ELISA) with a commercial antiserum. Based on the ELISA results, 18 out of 229 samples (7.86%) were infected with ApMV.

O virus do mosaico da macieira (APMV) é o patógeno viral mais importante da avelã. A região do Mar Negro é a principal área produtora de avelã na Turquia. Áreas de cultivo de avelã de Giresun, que estão localizadas na região do Mar Negro foram levantadas para a ocorrência e distribuição de APMV em 2011-2012. Amostras de folhas de avelã foram colhidas aleatoriamente a partir de plantas com e sem sintomas, onde se visualizava anéis amarelos alinhados na superfície foliar, amarelecimento em pontos localizados redução do limbo foliar e amarelecimento das nervuras. . Folhas coletadas para 229 amostras em 35 áreas (locais) foram analisadas para a presença do vírus do mosaico da macieira (VMM) usando ELISA com um antissoro comercial. Baseando na análise de ELISA 18 amostras foram positivas para o vírus (7,86 %) num total de 229.

Sequence analysis of the coat protein gene of Chinese soybean mosaic virus strain SC7 and comparison with those of SMV strains from the USA / 病毒学报

To unveil genetic variations between the predominant soybean mosaic virus (SMV) strains in China and in the USA, as well as to reveal the potential relevance between the similarity of gene sequences and the virulence of the viruses, we isolated and sequenced the coat protein (CP) gene of Chinese SMV strain SC7 by RT-PCR and compared the SC7 sequence with those of SMV strains from the USA. Analysis is showed that the CP gene of SC7 was 795 nucleotides in length and encoded 265 in amino acids'. The CP gene of SC7 and those of the strains from the USA exhibited 4%-5% nucleotide diversity and 1%-2% diversity amino acids. The conserved amino-acid sequence associated with aphid spread in the USA strains was DAG, and corresponded to DAD in SC7. The virulence of SC7 was greater than that of the SMV strains from the USA. Nevertheless, no clear relationships between sequence similarity of the CP genes from different strains and their virulence on differential hosts were found.

Benzothiadiazole (BTH) induces resistance to Pepper golden mosaic virus (PepGMV) in pepper (Capsicum annuum L.)

Pepper is an economically important crop in many countries around the world but it is susceptible to many diseases. In Mexico, diseases caused by bipartite begomoviruses have emerged as important problems in pepper. Several control strategies have been explored wiht little success; most of them are based on the avoidance of virus transmission and the breeding for resistance. Abiotic inducers can act at various points in the signaling pathways involved in disease resistance, providing long-lasting, wide-spectrum resistance. Benzothiadiazole (BTH) shares the property of activating the systemic acquired resistance pathway downstream from the SA signaling. In this work, resistance to PepGMV infection was induced in pepper plants by activating the SA pathway using BTH treatment. The resistance was characterized by evaluating symptom appearance, virus accumulation and viral movement. Our results showed that BTH could be an attractive alternative to induce geminivirus resistance in pepper plants without a significant damage of the fruit quality and productivity.

Reação fenotípica de genótipos de abóboras ao vírus da mancha anelar do mamoeiro, estirpe melancia (Pappaya ringspot virus, strain watermelon ­ PRSV-W) / Phenotypic reaction of Cucurbita spp. genotypes to Pappaya ringspot virus, watermelon strain ­ PRSV-W

O Pappaya ringspot vírus, estirpe melancia - PRSV-W, é a principal doença virótica das abóboras em condições tropicais. O trabalho objetivou avaliar a resistência fenotípica e o padrão de sintomas apresentados por genótipos de abóboras (Cucurbita spp.) ao PRSV-W. O experimento foi conduzido no delineamento inteiramente casualizado com quatro repetições e 10 plantas por parcela. Foram realizadas duas inoculações, a primeira na fase cotiledonar e a segunda cinco dias após a primeira. As plantas foram avaliadas quanto ao aparecimento de sintomas durante 30 dias, começando 10 dias após a segunda inoculação, através de uma escala de notas, em que: nota ­ 1: plantas com folhas sem sintomas de mosaico e; nota ­ 5: plantas com folhas apresentando mosaico intenso, com bolhosidade e presença de deformações foliares mais severas. Foram avaliados nove genótipos, dos quais três são regionais [ABTO#01 e ABTO#02 (C. maxima); ABTO#03 (C. moschata)]; e seis são cultivares comerciais [cv. Caserta (C. pepo); cvs. Menina Brasileira; Paulista; Baianinha; Jacarezinho (C. moschata); e o híbrido interespecífico Tetsukabuto ou Kabutiá (C. máxima x C. moschata)]. Também foram avaliadas progênies endogâmicas do acesso ABTO#01. Apenas o genótipo regional ABTO#01 não apresentou sintomas durante o período de avaliação, sendo considerado resistente. Todos os genótipos comerciais foram suscetíveis e os sintomas apresentados foram bolhosidades, mosaicos, estreitamento foliar e subdesenvolvimento. Todas as progênies endogâmicas oriundas do acesso ABTO#01 avaliadas foram resistentes ao PRSV-W e, portanto, constituem progênies promissoras para serem utilizadas em programas de melhoramento genético da abóbora para a região do Tocantins.

The Pappaya ringspot virus, watermelon strain - PRSV-W is the most important viral disease of Cucurbita spp. in the tropical conditions. The study evaluated the phenotypic resistance and the pattern of symptoms presented by the genotypes of Cucurbita spp. to PRSV-W. The experiment was conducted in completely randomized design with four replications. The plants were evaluated for symptoms 30 days after inoculation, using a scale where: Note - 1: plants with no symptoms of mosaic and; note - 5: plants with leaves showing mosaic intense with blistering and the presence of more severe leaf deformation. Nine genotypes were evaluated, three landraces [ABTO#01; ABTO#02 (C. maxima) e ABTO#03 (C. moschata) and six commercial cultivars [cv.Caserta (C. pepo); cvs. Menina Brasileira; Paulista; Baianinha; Jacarezinho (C. moschata) and the interspecific hybrid Tetsukabuto or Kabutiá (C. moschata x C. maximum)]. Inbred progenies from ABTO#01 were also evaluated. All commercial genotypes were susceptible and symptoms were blistering, mosaics, leaf narrowing and underdevelopment. The genotype ABTO#01 and their inbred progeny presented no virus symptoms during the evaluation period, being considered resistant and a promising genotype to be used in breeding programs of the Cucurbita spp. aiming resistance to PRSV-W.

Molecular modeling and conformational analysis of native and refolded viral genome-linked protein of Cardamom mosaic virus.

The viral genome-linked protein (VPg) of Potyviruses is covalently attached to the 5’ end of the genomic RNA. Towards biophysical characterization, the VPg coding region of Cardamom mosaic virus (CdMV) was amplified from the cDNA and expressed in E. coli. Most of the expressed VPg aggregated as inclusion bodies that were solubilized with urea and refolded with L-arginine hydrochloride. The various forms of CdMV VPg (native, denatured and refolded) were purified and the conformational variations between these forms were observed with fluorescence spectroscopy. Native and refolded CdMV VPg showed unordered secondary structure in the circular dichroism (CD) spectrum. The model of CdMV VPg was built based on the crystal structure of phosphotriesterase (from Pseudomonas diminuta), which had the maximum sequence homology with VPg to identify the arrangement of conserved amino acids in the protein to study the functional diversity of VPg. This is the first report on the VPg of CdMV, which is classified as a new member of the Macluravirus genus of the Potyviridae family.

Assembly of recombinant coat protein of sugarcane streak mosaic virus into potyvirus-like particles.

Coat protein (CP) gene of sugarcane streak mosaic virus-AP isolate (SCSMV-AP) was expressed in E. coli and recombinant CP (SCSMV-AP rCP) was purified by linear sucrose density gradient centrifugation. Observation of purified SCSMV-AP rCP under electron microscope revealed the presence of potyvirus-like particles (PVLPs). The assembled particles were shown to encapsidate CP gene transcripts by slot-blot hybridization.

Complete nucleotide sequence analysis of Cymbidium mosaic virus Indian isolate: further evidence for natural recombination among potexviruses.

The complete nucleotide sequence of an Indian strain of Cymbidium mosaic virus (CymMV)was determined and compared with other potexviruses. Phylogenetic analyses on the basis of RNA-dependent RNA polymerase (RdRp), triple gene block protein and coat protein (CP) amino acid sequences revealed that CymMV is closely related to the Narcissus mosaic virus (NMV), Scallion virus X (SVX), Pepino mosaic virus (PepMV)and Potato aucuba mosaic virus (PAMV). Different sets of primers were used for the amplification of different regions of the genome through RT-PCR and the amplified genes were cloned in a suitable vector. The full genome of the Indian isolate of CymMV from Phaius tankervilliae shares 96-97% similarity with isolates reported from other countries. It was found that the CP gene of CymMV shares a high similarity with each other and other potexviruses. One of the Indian isolates seems to be a recombinant formed by the intermolecular recombination of two other CymMV isolates. The phylogenetic analyses, Recombination Detection Program (RDP2)analyses and sequence alignment survey provided evidence for the occurrence of a recombination between an Indian isolate (AM055720) as the major parent, and a Korean type-2 isolate (AF016914) as the minor parent. Recombination was also observed between a Singapore isolate (U62963) as the major parent,and a Taiwan CymMV (AY571289) as the minor parent.

Caracterización de un tobamovirus aislado de plantas de canavalia (Canavalia ensiformis L.) en una parcela experimental del Edo. Aragua Venezuela / Characterization of a tobamovirus isolated from canavalia (Canavalia ensiformis L) in an experimental parcel at Aragua-State Venezuela

Se identificó un Tobamovirus infectando al cultivo de canavalia en una parcela experimental del estado Aragua, Venezuela. El rango de hospedantes y las pruebas serológicas basadas en la técnica de Western blot, permitieron determinar que el virus en estudio es un aislamiento del virus del mosaico del tabaco (TMV). Este resultado fue confirmado por el análisis de secuencia del gen de la proteína de la cápside, amplificado mediante RT-PCR, el cual reveló una identidad cercana al 98 por ciento entre el aislamiento descrito en esta investigación y cepas de TMV reportadas en Korea y Japón.

Detection of two viruses infecting Pinellia ternata in China / 中国中药杂志

<p><b>OBJECTIVE</b>To study viruses infecting Pinellia ternata in China.</p><p><b>METHOD</b>Symptom observation, DAS-ELISA and RT-PCR detection were applied.</p><p><b>RESULT AND CONCLUSION</b>During a survey in early spring, SMV and CMV were both commonly distributed as main viruses infecting P. ternata collected from different areas in China. But DsMV was the virus which infected P. ternate in natural condition. The infection ratio of cultivated P. ternate by SMV and CMV were 71.4% and 14.3% respectively for 21 samples collected from Ningbo, Zhejiang province; 100% and 44.4% for 18 samples from Xiaoshan, Zhejiang province; 61.9% and 33.3% for 21 samples from Hebei province; 50.0% and 41.7% for 12 samples from Anhui province; 16.7% and 16.7% for 12 samples from Sichuan province; 31.3% and none for 16 samples from Beijing. And the infection ratio of 25 wild samples from different areas of China infected by SMV and CMV were both 20.0%.</p>

Research on secretion expression in Pichia pastoris and function of the HC-pro gene of watermelon mosaic virus / 生物工程学报

HC-pro gene of Watermelon Mosaic virus was obtained by RT-PCR was 1371bp in length. It was cloned into pPI(9K, then the eucaryotic recombinant expression plasmid pPIC9K-WHC was constructed. After being linearized with restriction endonuclease Sal I , the recombinant plasmid was transformed into Pichia pastoris GS115 by electroporation. The high copy transformants with Mut+ /His+ phenotype were selected by RT-PCR and screening on G418, MD and MM medium. Induced by methanol for 5 days, the culture supernatant was analyzed by SDS-PAGE, the results showed that a specific protein with a molecular weight of about 66 kD was expressed. Western blot analysis proved that the expression protein could specifically bind to HC-Pro polyclonal antibody. Far western blot analysis proved that the expression protein could bind to coat protein, given support to "bridge" hypothesis that HC-Pro help aphid transmission of non-persistent viruses.

Efeito da época de inoculação do vírus do mosaico das nervuras por Aphis gossypii Glover (Hemiptera: Aphididae) no desenvolvimento e na produção do algodoeiro / Effect of the time of inoculation of the cotton vein mosaic virus by Aphis gossypii Glover (Hemiptera: Aphididae) on growth and yield of cotton plants

O pulgão Aphis gossypii Glover é vetor do vírus do mosaico das nervuras do algodoeiro (VMNA), que pode ocasionar sérios prejuízos à cultura algodoeira. O objetivo deste trabalho foi avaliar o efeito da época de inoculação do VMNA pelo pulgão no desenvolvimento e na produção das plantas de algodoeiro. O ensaio foi conduzido em casa-de-vegetação da UNESP - Universidade Estadual Paulista, em Jaboticabal, SP. Plantas de algodoeiro da cultivar CNPA ITA 90 com 20, 27, 34, 41, 48 e 55 dias após a emergência (DAE) receberam um adulto áptero e virulífero de A. gossypii, que permaneceu confinado nas plantas por um Período de Acesso à Inoculação (PAI) de 48h. Avaliou-se a percentagem de plantas com os sintomas da doença e a influência nos aspectos fenológicos das plantas de algodoeiro. A idade das plantas não influenciou a eficiência de transmissão do VMNA, com percentagens de plantas com sintomas da doença variando de 40 por cento a 65 por cento (20 e 48 DAE, respectivamente). A altura das plantas sofreu reduções de 54,5 por cento (20 DAE) a 1,3 por cento (55 DAE) em relação às plantas testemunhas. O número e diâmetro das maçãs também foram influenciados pela idade das plantas no momento da inoculação. Plantas inoculadas aos 20 DAE não produziram algodão. Plantas inoculadas aos 55 DAE produziram 20,7 g/planta, sendo significativamente inferior ao observado nas plantas sadias (35,9 g/planta). A severidade dos sintomas é diretamente relacionada com a idade das plantas de algodoeiro no momento da infecção.

Transgene elimination in genetically modified dry bean and soybean lines

Transgene elimination is a poorly studied phenomenon in plants. We made genetic and molecular studies of a transgenic dry bean line immune to bean golden mosaic geminivirus and a soybean line. In both lines, the transgenes were stable during the vegetative phase but were eliminated during meiosis. Due to its potential biotechnological value, this transgenic line was micropropagated by grafting and the vegetative copies were studied for more than two years. More than 300 plants of progeny were obtained during this period, demonstrating that the phenomenon of elimination was consistently repeated and offering an opportunity for detailed study of transgene elimination, including the characterization of the integration sites. Cloning and sequencing of the transgenic loci, reciprocal crosses to untransformed plants, genomic DNA blots, and GUS assays were performed in the transgenic lines. Based on the molecular and genetic characterization, possible mechanisms involved in transgene elimination include intrachromosomal recombination, genetic instability resulting from the tissue culture manipulations, and co-elimination of transgenes, triggered by a process of genome defense.

Construction and primary analysis of subtractive library induced by soybean mosaic virus (SMV) / 生物工程学报

SMV is one of main diseases of soybean, which could affect yields and quality of soybean seriously. It was effective to soybean breeding by studying the expression of resistant gene to SMV with molecular technology. In this study, a soybean resistance line, DongNong 8143, was used to construct a subtractive cDNA library by SSH from soybean leaves inoculated by SMV No.1 at primary stage. cDNA dominantly or specifically expressed in infected leaves was purified using PCR Purification Kit and cloned into pGEM-T easy vector. Colonies were grown on LB-agar plates containing ampicillin, X-gal and IPTG. A subtractive plasmid library was constructed by SSH. Then the library was transformed to host bacteria E. coli DH5alpha, and the titer of the library was measured as 2 x 10(3) . 64 clones were picked up randomly and sequenced. Of them there is 50 clones which result of sequenced were good. The length of EST fragment varied from 136bp to 691bp, and the average length is 456bp. Among them, 41 sequences has poly(A). Through ESTs were compared with sequences in unigene database of GeneBank with BLASTn and BLASTx algorithm, 38 ESTs of them had comparatively clear results and the percent of them in acquired ESTs is 74%. The EST expression profile showed that the resistance-related genes include cell protection, signal transduction, restrict pathogen growth, system acquired resistance, and house-keeping gene. There are 12 ESTs, which have not comparatively clear results, that maybe new genes.

Isolation of the capsid protein gene of maize dwarf mosaic virus and its transformation in maize / 生物工程学报

The MDMV (Maize Dwarf Mosaic Virus, MDMV) CP (Coat Protein, CP) gene was cloned by RT-PCR method and introduced into the embryonic calli derived from immature embryos of elite inbred 18-599hong and 18-599bai via particle bombardment. Bombarded calli were selected on selection medium containing 5-10 mg/L (PPT) Bialaphos. From resistant calli, 79 plantlets were regenerated. 18 of 79 were grown and harvested. The results of Southern blotting and PCR analysis demonstrated that MDMV CP have been integrated into the genome of the transgenic plants. PCR-positive progeny plants were artificially inoculated with MDMV strain B, and the average chlorosis of the functional leaves of each plant was investigated. The typical symptoms were observed from the leaves of the control inbreds. while, the presence of the MDMV CP gene provided resistance to inoculation with MDMV strain B.

High genetic diversity in the coat protein and 3 untranslated regions among geographical isolates of Cardamom mosaic virus from south India.

A survey was conducted to study the biological and genetic diversity of Cardamom mosaic virus (CdMV) that causes the most widespread disease in the cardamom growing area in the Western Ghats of south India. Six distinct subgroups were derived based on their symptomatology and host range from the sixty isolates collected. The serological variability between the virus isolates was analysed by ELISA and Western blotting. The 3 terminal region consisting of the coat protein (CP) coding sequence and 3 untranslated region (3 UTR) was cloned and sequenced from seven isolates. Sequence comparisons revealed considerable genetic diversity among the isolates in their CP and 3 UTR, making CdMV one of the highly variable members of Potyviridae. The possible occurrence of recombination between the isolates and the movement of the virus in the cardamom tract of south India are discussed.

Infectividade e proteção de três estirpes fracas do Papaya ringspot virus em plantas de melancia / Infectivity and protective effect of three mild strains of papaya ringspot virus in watermelon plants

Este trabalho teve como objetivo avaliar a infectividade de estirpes fracas do Papaya ringspot virus - type W (PRSV-W) em plantas de melancia (Citrullus lanatus), em função da origem da estirpe fraca, da concentração e da espécie doadora do inóculo e da idade da planta-teste de melancia, inoculada mecanicamente. Também foi avaliado o efeito protetor dessas estirpes em plantas de melancia em casa de vegetação e em campo. Uma estirpe fraca do vírus, denominada PRSV-W-3, foi selecionada de bolhas de folhas de melancia com mosaico. Em todos os testes de infectividade em plantas de melancia, independente da concentração e da planta fonte do inóculo e do estádio de desenvolvimento da planta-teste inoculada, a estirpe fraca PRSV-W-3 apresentou taxas de infectividade semelhantes as das estirpes PRSV-W-1 e PRSV-W-2, chegando a 100 por cento em alguns casos. A infectividade da estirpe severa PRSV-W-C foi de 100 por cento em todos os testes. Aparentemente, a infectividade das três estirpes fracas foi mais diretamente afetada pela intensidade de fricção das folhas no momento da inoculação mecânica do que pelas variáveis estudadas. A estirpe fraca PRSV-W-3 protegeu as plantas de melancia contra a infecção e/ou manifestação da estirpe PRSV-W-C em casa de vegetação. Em campo, todas as plantas de melancia premunizadas com as três estirpes fracas também ficaram protegidas contra a estirpe severa utilizada no desafio. A produção das plantas premunizadas não diferiu estatisticamente entre si, nem mesmo daquelas inicialmente sadias infectadas em campo. O conteúdo de açúcares e a aparência da polpa dos frutos também foram semelhantes em todos os tratamentos.

Depurination of ribosomal RNA and inhibition of viral RNA translation by an antiviral protein of Celosia cristata.

An antiviral protein (25 kD) isolated from leaves of Celosia cristata (CCP 25) was tested for depurination study on ribosomal RNA from yeast. Ribosomal RNA yielded 360 nucleotide base fragment after treatment with CCP 25 indicating that CCP 25 was a ribosome inactivating protein. CCP 25 also inhibited translation of brome mosaic virus (BMV) and pokeweed mosaic virus (PMV) RNAs in rabbit reticulocyte translation system. The radioactive assay showed that incorporation of [35S]-methionine was less in translation proteins of BMV nucleic acid when CCP 25 was added to translation system. This indicated that antiviral protein from Celosia cristata not only depurinated ribosomal RNA but also inhibited translation of viral RNA in vitro.