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The identification of source of resistance in cultivated cucurbits species is very important for the development of resistant cultivars to control diseases caused by virus from the genus Potyvirus. The present research had the objective to evaluate the phenotypic reactions and the behavior of pumpkin (Cucurbita spp.) accessions to the virus species from the genus Potyvirus: Papaya ringspot virus type Watermelon (PRSV-W), Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV). Twenty-eight accessions of pumpkin from the Cucurbit Germplasm Bank from Embrapa Semiárido, Petrolina, PE, Brazil were evaluated. Twelve young plants from each pumpkin accession were inoculated with each one of the virus species and were maintained at greenhouse for their symptom reaction evaluations. All possible virus infections or absence of infection were confirmed by plate-trapped antigen enzyme linked immunosorbent assay (PTA-ELISA) against antisera specific to PRSV-W, ZYMV and WMV at the Plant Virus Laboratory, Universidade Federal do Ceará. Three pumpkin accessions showed extreme resistant to WMV and eight accessions presented mild mosaic when inoculated with PRSV-W. The most severe symptoms were observed on those accessions inoculated with ZYMV and 50% of the accessions showed to be highly susceptible. On the other hand, the pumpkin accessions inoculated with WMV presented the mildest symptoms, indicating that 39% of them were resistant, and 39% were tolerant. The Cucurbita spp. accessions BGC 518, BGC 530, BGC 567, and BGC 683 that showed resistance to one or more than one virus species constitute promising sources of resistance for developing virus resistant pumpkin cultivars or hybrids.

Passion fruit (Passiflora edulis) and cowpea (Vigna unguiculata) are two agricultural crops of considerable economic importance in Northeastern Brazil. Fruit woodiness caused by isolates of Cowpea aphid-borne mosaic virus biotype P (CABMV-P) is the most important virus disease that occurs on passion fruit in Brazil and the biotype cowpea (CABMV-C) is responsible for the most common and important virus disease of cowpea in Northeastern Brazil. The objective of the present research was to determine the biological relationships between isolates of biotype CABMV-C obtained from cowpea (CABMV-CFor and CABMV-CBv) and isolates of biotype CABMV-P obtained from passion fruit (CABMV-PMild and CABMV-PSevere) in common hosts. In host range studies involving 25 plant species only Canavalia ensiformis and Macroptilium lathyroides were shown to be common systemic hosts for all virus isolates. Cross protection studies were developed between CABMV-PMild and CABMV-PSevere in passion fruit and between CABMV-PSevere and CABMV-CFor in C. ensiformis. Unilateral cross protection was detected between CABMV-PSevere and CABMV-CFor in C. ensiformis, but CABMV-PMild did not cross protect passion fruit against CABMV-PSevere. RESUMO Maracujazeiro (Passiflora edulis) e feijoeiro caupi (Vigna unguiculata) são duas culturas economicamente importante para o Nordeste do Brasil. O endurecimento dos frutos causado por isolados de Cowpea aphid-borne mosaic virus biótipo P (CABMV-P) é a virose mais importante que ocorre no maracujazeiro no Brasil e o biótipo caupi (CABMV-C) é responsável pela virose mais comum e importante que afeta o feijoeiro caupi. O objetivo desta pesquisa foi determinar as relações biológicas entre isolados do biótipo CABMV-C obtido de feijoeiro caupi (CABMV-CFor e CABMV-CBv) e isolados do biótipo CABMV-P obtidos de maracujazeiro (CABMV-PFraco e CABMV-PSevera) em hospedeiros comuns. Em estudos de gama de plantas hospedeiros, envolvendo 25 espécies de plantas, somente Canavalia ensiformis e Macroptilium lathyroides mostraram ser hospedeiros sistêmicos comuns a todos os isolados virais. Estudos de proteção cruzada foram desenvolvidos entre CABMV-PFraco e CABMV-PSevero em maracujazeiro e CABMV-PSevero e CABMV-CFor em C. ensiformis. Proteção cruzada unilateral foi detectada entre CABMV-PSevero e CABMV-CFor em C. ensiformes, mas CABMV-PFraco não protegeu maracujazeiro contra o CABMV-PSevero.

Cowpea (Vigna unguiculata) is an important crop of the traditional agriculture system in the Northeast of Brazil. It can be infected by more than 20 virus species and Cowpea severe mosaic virus (CPSMV) is one of the most important pathogens that naturally infect cowpea in Brazil. Several CPSMV isolates were obtained and characterized in the Plant Virus Laboratory at the Federal University of Ceará: CPSMV-CE - the first characterized isolate of the virus obtained from cowpea in the State of Ceará; CPSMV-AL - isolated from cowpea in Alagoas; CPSMV-PE - isolated from cowpea in Pernambuco; CPSMV-PR - obtained from soybean (Glycine max) in Paraná and CPSMV-CROT - isolated from Crotalaria paulinea, in Maranhão. An isolate of CPSMV with the property to infect the cv. Macaibo, a cowpea cultivar immune to most of CPSMV isolates was also biologically and serologically characterized as a new strain of the virus (CPSMV-MC). The CPSMV-MC was isolated in January 1990 and has been evaluated over 20 years by host range studies and maintenance in vivo by periodical mechanical inoculations in cowpea. The results of this periodical evaluation revealed that the biological integrity and the serological properties of CPSMV-MC were preserved over 20 years, indicating that the genetic preservation of a virus strain could occur over the years. Molecular studies involving part of the coat protein (CP) gene of CPSMV-MC and five other Brazilian CPSMV isolates indicated a high degree of conservation, with 92-100% nucleotide sequence identity among the isolates. O feijão-caupi (Vigna unguiculata) é uma cultura do sistema tradicional do Nordeste do Brasil, que pode ser infetada por mais de 20 espécies de vírus, sendo o vírus do mosaico severo do caupi (Cowpea severe mosaic virus, CPSMV) um dos mais importantes patógenos que infeta naturalmente essa leguminosa no Brasil. Vários isolados do CPSMV foram obtidos e caracterizados no Laboratório de Virologia Vegetal da UFC: CPSMV-CE - o primeiro isolado do vírus obtido no Ceará; isolados obtidos de feijão-caupi: CPSMV-AL (Alagoas) and CPSMV-PE (Pernambuco); CPSMV-PR - isolado de soja (Glycine max) no Paraná e CPSMV-CROT - isolado de Crotalaria paulinea no Maranhão. Um isolado de CPSMV capaz de infetar o cv. Macaibo, cultivar de ffeijão-caupi imune a todos os demais isolados de CPSMV foi biológica e sorologicamente caracterizado e designado de CPSMV-MC. O CPSMV-MC obtido em janeiro de 1990 vem sendo avaliado através de estudos de gama de hospedeiro e mantido in vivo através de inoculações periódicas em feijão-caupi. Os resultados dessas avaliações revelaram que a integridade biológica e as propriedades sorológicas do CPSMV-MC foram preservadas ao longo dos anos, indicando que a preservação das propriedades genéticas de uma estirpe viral pode acontecer através dos anos. Estudos moleculares adicionais revelaram que a seqüência de nucleotídeos correspondente a parte do gene da capa protéica de cinco isolados de CPSMV, incluindo o CPSMV-MC, possui elevado grau de conservação, com 92-100% da seqüência de nucleotídeos idêntica entre os isolados.

O vírus do amarelo letal do mamoeiro (Papaya lethal yellowing virus, PLYV) é responsável por uma das principais doenças do mamoeiro (Carica papaya) no Nordeste brasileiro. O PLYV pode ser transmitido através do solo, água, instrumento de corte e mãos contaminadas. A presente pesquisa teve como objetivo estudar as características biológicas, sorológicas e físicas de um isolado do vírus e avaliar sua sobrevivência em tecido seco infetado. O PLYV foi detectado por "Enzyme linked immunosorbent assay" (ELISA) indireto e isolado em mudas de mamoeiro, através da inoculação mecânica. A sobrevivência do PLYV em folhas e raízes secas de mamoeiro infetado foi avaliada por sorologia e inoculação em plantas sadias. A presença do vírus foi detectada em folhas e raízes de mamoeiro secas, indicando que o vírus pode permanecer ativo em restos de cultura por até 120 dias. A purificação do PLYV permitiu a obtenção de 309.5 mg de vírus/kg de folha e o anti-soro obtido mostrou-se altamente específico, com títulos de 1:128 em dupla difusão em Agar e 1:1.024.000 em Elisa indireto. Estudos das propriedades físicas do PLYV em mamoeiro revelaram um ponto de inativação térmica (PIT) em torno de 80 ºC, um ponto máximo de diluição (PMD) de ac. 10-6 e uma longevidade in vitro (LIV) acima de 50 dias. The Papaya lethal yellowing virus (PLYV) is responsible for one of the most important disease of papaya (Carica papaya) in the Northeast of Brazil. The PLYV can be transmitted through the soil, irrigation water, agriculture tools and contaminated hands. The present research had the objective to characterize biologically, serologically and physically a PLYV isolate and evaluates how long it survives in infected dried tissues. The PLYV was identified by indirect enzyme linked immunoabsorbent assay (ELISA), isolated in young papaya plants by mechanical inoculations and maintained at green house conditions for virus purification. Approximately 309.5 mg of virus was purified per kg of infected papaya leaves and a polyclonal antiserum was obtained from an immunized rabbit. The antiserum obtained was shown to be highly specific to PLYV with a titer of 1:128 in double immune-diffusion and a titer of 1:1.024.000 in indirect ELISA. The virus was detected in dried roots and leaves maintained at room temperature up to 120 days, confirming its high stability within nonliving plant tissues, which could explain its dissemination by contaminated hands, tools, water and soil. The physical properties determined for the virus revealed a thermal inactivation point of 80 ºC, longevity in vitro over 50 days and dilution end point ac. of 10-6.

O Nordeste brasileiro possui condicoes edafoclimaticas favoraveis ao cultivo do meloeiro (Cucumis melo). No entanto, diferentes problemas fitossanitarios afetam sua produtividade, destacando-se as doencas ocasionadas por virus. A presente pesquisa objetivou efetuar a caracterizacao biologica e sorologica de um isolado de Squash mosaic virus (SqMV) obtido no Ceara. Em estudos de gama de hospedeiros o virus infetou sistemicamente somente cinco especies da familia Cucurbitaceae e ocasionou lesoes locais em Chenopodium amaranticolor e C. quinoa. Estudos da infeccao mista do SqMV com virus do genero Potyvirus demonstraram efeito sinergico entre os mesmos. A purificacao quimica do SqMV foi possivel a partir de plantas de meloeiro e a imunizacao em coelho com a preparacao purificada possibilitou a producao de antissoro policlonal especifico. O antissoro produzido apresentou titulos de 1:10.000 quando avaliado por plate trapped antigen enzyme linked immune absorbent assay (PTA-ELISA), de 1:160.000 em immune-precipitation ELISA (IP-PTA-ELISA) e de 1:1.024 em Dupla Difusao em Agar. Estudos do relacionamento sorologico entre SqMV e Cowpea severe mosaic virus (CPSMV) do genero Comovirus contra seus antissoros homologos e heterologos em Dupla Difusao em Agar demonstraram relacionamento unilateral entre os mesmos.