Aspectos microscópicos, fisiológicos, bioquímicos e moleculares do silício na interação sorgo - Colletotrichum sublienolum

• Ano de defesa: 2011
• Autor(a) principal: Resende, Renata Sousa
• Orientador(a): Rodrigues, Fabrício de ávila
• Banca de defesa: Damatta, Fábio Murilo , Cota, Luciano Viana , Pereira, Olinto Liparini , Maffia, Luiz Antônio
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Microscopia; Nutrição mineral; Doença foliar
• Palavras-chave em Inglês: Microscopy; Mineral nutrition; Foliar disease
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1041

One of the most important roles of silicon (Si) is the increased resistance of plants, especially monocots, against pathogens. However, despite many studies showing an active role of this element in plant resistance to diseases, nothing is known about the multiple defense mechanisms modulated by this element in sorghum-Colletotrichum sublienolum pathosystem. Thus, the objective of this study was to evaluate the effect of Si on reducing the severity of anthracnose, as well as to study the microscopic, physiological, biochemical and molecular aspects of resistance mediated by this element. In addition, to investigate how Si affects the photosynthetic capacity of the antioxidant metabolism in sorghum. To evaluate the effect of Si in the soil, in combination or not with the application of fungicide resistance in two sorghum lines (BR008 (moderately resistant) and BR009 (susceptible) to anthracnose, the experiments were conducted under field conditions used as a source of Si, the calcium silicate. The results of this study showed that application of Si reduced the severity of sorghum anthracnose and, consequently, increased productivity, especially using a susceptible line, both in the first year of seeding and second year (residual effect of calcium silicate slag in the first year). The increased activity of defense enzymes peroxidase (POX) and polyphenoloxidase (PPO) in plants supplied with Si supports the hypothesis that the defense mechanism activated by this element does not was just a physical barrier as demonstrated by microscopic analysis. The gas exchange parameters A, gs and E were higher and the concentration of malonic aldehyde (MDA) and electrolyte leakage (EE) were lower in plants supplied with Si and infected with C. sublineolum when it were compared with plants not supplied with this element, suggesting that the Si maintained the integrity of the plasmatic membrane of cells of the leaves. The Si also changed the hormonal signaling pathways activated by C. sublineolum because the transcripts of marker genes such as ACC oxidase, and also GH3.1 of genes related to the ways of jasmonic acid and salicylic acid were induced in plants inoculated and supplied with Si. The results of this study suggest that the Si can interact with many key components of the immune and physiological sorghum system, increasing their resistance to the pathogen.