Bean pod mottle virus (BPMV), a member of the genus Comovirus in the family Comoviridae, is widespread in the major soybean-growing areas in the United States. Soybean yield losses of 10-40% have been reported as a consequence of BPMV infection. The complete nucleotide sequences of two strains, K-Ha1 and K-Ho1, were determined. Field isolates of BPMV were classified into two distinct subgroups (I and II) based on slot blot hybridization and sequence analyses. Full-length cDNA clones from which infectious transcripts can be produced were constructed for strains K-G7, K-Ho1 and K-Ha1. Whereas strains K-Ha1 and K-G7 induced mild or moderate symptoms in infected soybean plants, strain K-Ho1 produced very severe symptoms. Symptom severity was mapped to RNA1. Chimeric RNA1 constructs were generated by exchanging full or partial coding regions of the five RNA1-encoded mature proteins between the full-length cDNA clones of the three RNA1s and the resultant transcripts were inoculated onto soybean. The results showed that the coding regions of the protease co-factor (Co-pro) and the putative helicase (Hel) are determinants of symptom severity. Although symptom severity correlated well with accumulation of viral RNA, neither the Co-pro nor Hel protein could be demonstrated as a suppressor of RNA silencing. Furthermore, separate expression of the Co-pro or Hel proteins from a PVX vector induced necrosis on the inoculated leaves of Nicotiana benthamiana. Characterization of BPMV K-Ho1 indicated that it is a diploid reassortant, containing two distinct types of RNA1s and one type of RNA2. Examination of field isolates from various locations in the United States and Canada revealed that diploid reassortants are of frequent occurrence in natural populations of BPMV. The vary severe symptoms induced by BPMV K-Ho1 can be mimicked by inoculation of plants with a mixture of RNA1 transcripts from two distinct strain subgroups and RNA2 transcript from either subgroup. Plants inoculated with a mixture of transcripts containing two types of RNA1 from the same strain subgroup did not produce very severe symptoms. These are due to interactions between two distinct types of RNA1s. At present, no soybean cultivars with resistance to BPMV are commercially available. Therefore, the feasibility of cross protection as an alternative disease management strategy was studied. Two mild strains of BPMV (K-Da1 and K-Ha1), belonging to subgroup II, were tested for their ability to protect infected plants against a severe strain (K-Ho1). Inoculation of the soybean cultivar Essex on the primary leaves with either of the two mild strains conferred complete protection against challenge inoculation with the severe strain K-Ho1, regardless of the timing of challenge inoculation. Cross-protection was evident regardless of whether virions or BPMV-RNA were used as inocula. Cross protection was independent of the soybean cultivar used and method of virus inoculation, sap-inoculation or by the bean leaf beetle, vector of BPMV. Protection was complete and durable.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-04-12T14:23:24Z No. of bitstreams: 1 Carla Caroline Alves Pereira.pdf: 600271 bytes, checksum: 8a9e9348fcbecb54d936533d542b8419 (MD5) / Made available in DSpace on 2017-04-12T14:23:24Z (GMT). No. of bitstreams: 1 Carla Caroline Alves Pereira.pdf: 600271 bytes, checksum: 8a9e9348fcbecb54d936533d542b8419 (MD5) Previous issue date: 2017-02-17 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Bean-pod is a horticultural crop widely appreciated in Brazilian cuisine, due to its chemical and organoleptic composition, high protein content and easy digestibility. Due to these characteristics, it is a food with high market potential, but because it is a relatively new agricultural crop that requires intensive activity for its cultivation, it is still little explored commercially. For the cultivation of the bean pod to gain representativeness it is necessary to genetically improve some characteristics, such as productivity, improvement in pod quality and resistance to pests and diseases. Among the characteristics that most influence the quality of the pod, we can mention the decrease in fiber content, which is directly related to changes in the physicochemical composition of the product, which promotes better palatability and ease of digestion. The consumption of food that consists of fiber is essential to maintain health. Due to this, differences in dietary fiber composition have been observed in bean germplasm banks when grown at different locations, years and sowing times. Based on what has already been discussed, the objective of this work was to evaluate the production components and to establish selection strategies for fiber content in bean-pod genotypes. The experiment was conducted at the Federal Rural University of Pernambuco (UFRPE), Recife Campus, from December 2015 to March 2016. The treatments were composed of 18 genotypes, consisting of sixteen accessions from the germplasm bank of Universidade Estadual do Norte Fluminense (UENF) and by two commercial varieties. The experimental design was in randomized blocks, with three replications. Crops were harvested throughout the pod production period, according to the harvest point of each genotype. The following characteristics were evaluated: number of days for flowering (NDPF), average number of pods per plant (NMVP), average pod length (CMV), average pod weight per plant (PMV), average pod yield (PRODMV) and fiber content in pods (TFV). The analysis of variance and the grouping of means by Scott-Knott's test at 5% of probability were performed by the software program Genes. To evaluate the production components and selection strategies for fiber content in bean genotypes. The lines UENF 7-5-1, UENF 7-4-1, 7-6-1 and Hortivale presented low fiber contents and better yields. The most appropriate strategy aiming at low fiber content is to select the genotypes that are in the range of the mean up to ± 2σ. / O feijão-vagem é uma cultura hortícola muito apreciada na culinária brasileira, devido a sua composição química e organoléptica, possuindo alto teor de proteínas e fácil digestibilidade. Em função dessas características é um alimento com alto potencial de mercado, porém por ser uma cultura agrícola relativamente nova e que exige uma atividade intensiva para o seu cultivo ainda é pouco explorada comercialmente. Para que o cultivo do feijão-vagem ganhe representatividade é necessário melhorar geneticamente algumas características, como produtividade, melhoria na qualidade das vagens e resistência a pragas e doenças. Dentre as características que mais influenciam á qualidade da vagem, pode-se citar a diminuição do teor de fibras, que está diretamente ligado a mudanças na composição físico-química do produto, o que promove uma melhor palatabilidade e facilidade na digestão. O consumo de alimentos que em sua composição seja constituído por fibra é essencial para manter a saúde. Devido a isto, diferenças na composição de fibra alimentar têm sido observadas em bancos de germoplasma de feijão quando cultivados em diferentes locais, anos e épocas de semeadura. Em função do que já foi abordado, este trabalho teve como objetivo, avaliar os componentes de produção e estabelecer estratégias de seleção para teor de fibra em genótipos de feijão-vagem. O experimento foi conduzido na Universidade Federal Rural de Pernambuco (UFRPE), Campus Recife, no período de dezembro de 2015 a março de 2016. Os tratamentos foram compostos por 18 genótipos, constituído por dezesseis acessos oriundos do banco de germoplasma de feijão-vagem da Universidade Estadual do Norte Fluminense (UENF) e por duas variedades comerciais. O delineamento experimental utilizado foi em blocos casualizados, com três repetições. As colheitas foram efetuadas durante todo o período de produção de vagens, de acordo com o ponto de colheita de cada genótipo. No qual foram avaliadas as seguintes características: número de dias para a floração (NDPF), número médio de vagens por planta (NMVP), comprimento médio da vagem (CMV), peso médio de vagens por planta (PMV), produtividade média de vagens (PRODMV) e teor de fibras nas vagens (TFV). Foi realizada as análises de variância e o agrupamento das médias pelo teste de Scott-Knott a 5% de probabilidade, pelo programa de software Genes. Para avaliar os componentes de produção e estratégias de seleção para teor de fibra em genótipos de feijão-vagem. As linhagens UENF 7-5-1, UENF 7-4-1, 7-6-1 e Hortivale apresentaram baixos teores de fibras e melhores produtividades. A estratégia mais apropriada visando baixo teor de fibra é selecionando os genótipos que se encontram no intervalo entre a média até ±2σ.

The bean leaf beetle (BLB), Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), is a pest of commercially produced legumes in eastern Virginia. Field cage and manual-defoliation studies were conducted in Virginia to determine an economic impact of BLB. In the manual-defoliation study, snap bean plants had significant yield loss when > 25% of leaf area was removed. In the field cage experiments, I was unable to establish beetle densities per plant to impact yield. Host plant selection by BLB was done in laboratory and field studies with snap bean, lima bean, and soybeans. Laboratory studies showed that BLB preferred snap bean and lima bean over soybean. Field studies did not showed no preference. A survey was conducted on the Eastern Shore of Virginia determine the epicenter of BPMV. Soybean leaves and beetles were collected and assessed for BPMV by ELISA or TBIA. Beetles at the ESAREC were BPMV-positive upon emergence from overwintering sites, but the virus load was low when tested by ELISA. This suggests acquisition of virus from a source other than infected cultivated legumes. To find the potential inoculum sources of BPMV in eastern Virginia, leguminous weeds and perennial weeds were tested for BPMV. Four weed species gave BPMV-positive tissue blots including: Oxalis stricta, Rumex acetosella, Trifolium pretense, and Trifolium repens. Insecticidal seed treatment of thiamethoxam on soybean seeds was evaluated to test the efficacy. Leaf area eaten and beetle mortality was measured. The thiamethoxam seed treatment protected soybean seedlings from beetle feeding through the V2 stage of growth. / Master of Science in Life Sciences

Bean pod mottle virus (BPMV), a member of the genus Comovirus in the family Comoviridae, is widespread in the major soybean-growing areas in the United States. The complete nucleotide sequences of the genomic RNAs of the naturally occurring partial diploid strain IL-Cb1 were determined. Intermolecular RNA1 recombinants were isolated from strain IL-Cb1 and characterized at the molecular level. Structurally similar recombinant RNA1 was also generated after four passages in soybean derived from plants previously inoculated with a mixture of infectious RNA1 transcripts from two distinct strains. BPMV was developed as a plant viral vector that is appropriate for gene expression and virus-induced gene silencing (VIGS) in soybean. The foreign gene was inserted between the movement protein (MP) and the large coat protein (L-CP) coding regions. The recombinant BPMV constructs were stable following several serial passages in soybean and relatively high levels of protein expression were attained. Successful expression of several proteins with different biological activities was demonstrated from the BPMV vector. Double infection of soybean by BPMV and SMV triggers a synergistic interaction leading to a serious disease. To investigate the underlying mechanism, helper componentprotease (HC-Pro) genes from several SMV strains and TEV were expressed from BPMV vectors. The recombinant BPMV vectors carrying the HC-Pro genes from SMV strain G7 or TEV induced very severe symptoms on soybean whereas constructs containing the HC-Pro gene from SMV isolate P10, a mild strain with an apparent defect in synergism, induced only very mild symptoms. Transient agroinfiltration assays using GFP-transgenic Nicotiana benthamiana showed that HC-Pro from SMV isolate P10 was not a RNA silencing suppressor, whereas those of SMV strain G7 and TEV exhibited strong suppressor activities. Analysis of chimeric HC-Pro genes and point mutations indicated that a positively charged amino acid at position 144 is critical for the suppressor function of not only SMV HC-Pro but also other potyvirus HC-Pro proteins. Although amino acid substitution at position 144 resulted in changes in small RNA profile, it did not affect HC-Pro stability.