Análise funcional de genes de Phakopsora pachyrhizi candidatos a efetores utilizando o sistema EDV

• Ano de defesa: 2014
• Autor(a) principal: Möller, Priscilla Aguiar
• Orientador(a): Brommonschenkel, Sérgio Hermínio
• Banca de defesa: Oliveira, José Rogério de , Pacheco, Jorge Luis Badel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Phakopsora pachyrhizi; Soja - Doenças e pragas; Ferrugem-da-soja; Genética molecula
• Palavras-chave em Inglês: Phakopsora pachyrhizi; Soy - Diseases and pests; Crown rust soybean; Genetic molecule
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/4439

Rust fungi are obligate parasites that secrete diverse proteins during their interaction with host plants. These proteins promote parasitism by manipulating the host metabolism and interfering with its defense responses. Effector proteins can be recognized by proteins coded by plant resistance genes, in which case they are called avirulence proteins. Six loci containing genes that confer varying degrees of resistance to P. pachyrhizi (Rpp) have been reported, and several genes encoding proteins secreted by the fungus have been identified. However, effector proteins (Avr proteins) recognized by soybean Rpp proteins have not yet been identified. Thus, the objective of this study was to identify proteins secreted by P. pachyrhizi (PPUFV02) able to activate or suppress defense responses in soybean, through the functional analysis of ten candidate effector genes using the TTSS of P. savastanoi pv. glycinea 1462 (EDV system). Among the ten effectors tested in 11 soybean genotypes resistant to the mono-pustule isolate PPUFV02 of P. pachyrhizi, source of candidate genes, PHPA_RSP_71 stood out for contributing to greater disease severity in genotype PI 594538- A and lower in genotype PI 594754. The PHPA_RSP_23 effector was also interesting for additional functional studies on soybean and tobacco, since the results indicated a possible activation of defense response in soybean, in general (all genotypes), and a possible suppression of cell death in tobacco. The effector activity of these candidate genes was not confirmed by analysis of bacterial growth in soybean and tobacco (non-host plant). On the other hand, it is possible that these effects are due to an interference of the effector with the function of the TTSS, making it necessary to conduct protein secretion assays to confirm or reject these hypotheses. Overall, the genotype Williams 82 showed resistance to Psg 1462 and can be used as negative control for disease in functional analysis in soybean. It was not possible to confirm N. benthamiana as an appropriate plant for functional studies of induction/suppression of HR when using Psg 1462, since it is possible that the bacterial isolate is pathogenic to this species. The pEDV6 vector in general was stable in the Psg1462(pEDV6::PHPA_RSP) clones and did not alter the ability of the bacteria to multiply in planta, confirming the EDV as a good system for functional analysis of P. pachyrhizi candidate effector genes in soybean using TTSS of Psg 1462. The inoculation method by dipping was not suitable for functional analysis in soybean because, in general, showed highly variable results. The inoculation method by vacuum was the best suited for this purpose, since it introduced greater uniformity in the severity of symptoms observed.