Identificação de proteínas diferencialmente expressas em folhas de soja (Glycine max (L.) Merrill) em resposta a Phakopsora pachyrhizi.

• Ano de defesa: 2011
• Autor(a) principal: Pereira, Mateus Rodrigues
• Orientador(a): Barros, Everaldo Gonçalves de
• Banca de defesa: Ramos, Humberto Josué de Oliveira , Araújo, João Marcos de , Barbosa, Meire de Oliveira , Campos, José Marcello Salabert de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Biologia Celular e Estrutural
• Departamento: Análises quantitativas e moleculares do Genoma; Biologia das células e dos tecidos
• País: BR
• Palavras-chave em Português: Ferrugem asiática da soja; Proteômica; Eletroforese 2D; Espectrometria de massa; MALDI
• Palavras-chave em Inglês: Asian soybean rust; Proteomic; 2D electrophoresis; Mass spectrometry; MALDI
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL
• Link de acesso: http://locus.ufv.br/handle/123456789/247

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi Sydow, is considered one of the most aggressive diseases to the soybean culture, since there are no commercial cultivars immune to the pathogen. The use of fungicides is the most commonly applied control measure against the disease, but this procedure increases production cost and causes environmental problems. Plant disease control through genetic resistance is the most inexpensive and effective alternative. Genomic and proteomic studies have been carried out for molecular understanding of the host responses to pathogens, but there is little information on the molecular basis of the interaction between the ASR causal agent and soybean, which is needed for aiding genetic breeding efforts and the development of resistant cultivars. In this work, through the use of two-dimensional electrophoresis associated with mass spectrometry, ten proteins differently expressed were identified in soybean leaves in response to inoculation with spores of P. pachyrhizi. Two genotypes (PI561356 with partial resistance and Embrapa 48, susceptible) were evaluated at two time points after inoculation (72 h and 192 h). Leaves of non-inoculated control plants were collected for each time and genotype. Carbonic anhydrase, 1-deoxy-D-Xylulose-5-phosphatereductoisomerase (DXR) and subunit A of glyceraldehyde-3-phosphate-dehydrogenase (GAPDHa) were more abundantly expressed in the susceptible genotype 192 h after inoculation (h.a.i.), compared to the control. At the time point of 72 h.a.i., seven proteins differently expressed were identified when the inoculated resistant genotype was compared to the non-inoculated: translationally controlled tumor protein, gammaglutamyl hydrolase, chloroplast 30S ribosomal protein, elongation factor 1-alpha, Rubisco beta subunit binding protein (lower expression with inoculation), glutamine synthetase and fructose bisphosphate aldolase (higher expression with inoculation). Some of these proteins are involved in metabolic pathways related with host defense against pathogens. Previous studies indicate that carbonic anhydrase is a salicylic acid (SA) effector protein that plays an important role in systemic and local defense responses. Other studies demonstrate that the enzyme DXR is essential for phytoalexins biosynthesis. These compounds are isoprenoids involved in the defense against pathogen attack. The fructose bisphosphate aldolase participates in the pentose phosphate metabolism, which is one of the main pathways for production of phenolic compounds responsible for the activation of defense mechanisms. Glutamine synthetase acts on nitrogen metabolism, and studies indicate that reduced levels of nitrogen increase susceptibility to pathogens. The increased expression of GAPDHa indicates that accumulation of reactive oxygen intermediates is part of the response mechanisms of the systemic acquired resistance (SAR) against pathogen attack. Several studies show that photosynthesis and global protein synthesis tend to decrease after pathogen inoculation. This is in line with the observation that the Rubisco beta subunit binding protein, the chloroplast 30S ribosomal protein and elongation factor 1-alpha were less expressed in the genotype PI561356 72 h.a.i. Although the role of the translationally controlled tumor protein on response to infection by pathogens is still unknown, changes in the expression of this protein have been observed in other works, in response to different physiological conditions of the cell. The expression of proteins present in the xylem sap can be changed, as occurred with the gamma-glutamyl hydrolase, which was less expressed in genotype PI561356 72 h.a.i. Results from other studies show that changes in the expression of proteins present in the xylem sap inhibit the development of pathogens in plants. The genes encoding the enzymes carbonic anhydrase and DXR, which were more expressed in soybean leaves in the genotype Embrapa 48, 192 h.a.i., were analyzed in silico. Their expression was detected in EST (Expressed Sequence Tags) libraries of soybean leaves inoculated with P. pachyrhizi. The results obtained in this work will help the understanding of the mechanism of soybean response to P. pachyrhizi.