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Please use this identifier to cite or link to this item: http://hdl.handle.net/10400.5/3105

Título: Avaliação do papel dos ácidos salicilico, abcisico e jasmónico na interacção Coffea arabica - Hemileia vastatrix: implementação de um método de análise
Autor: Sá, Marta Filipa Batista
Orientador: Almeida, Maria Helena Guimarães
Palavras-chave: Coffea arabica
Hemileia vastatrix
cofee leaf rust
HPLC-DAD-MS/MS
salicylic acid
jasmonic acid
abscisic acid
Issue Date: 2010
Editora: ISA
Resumo: Coffee leaf rust, the most widespread disease of Coffea arabica L. cultivars, is caused by the fungus Hemileia vastatrix Berk. & Br.. The coffee – rust interaction is a gene-for-gene system that involves at least nine dominant plant resistant genes, singly or associated. Previous cytological studies have shown that coffee resistance to H. vastatrix is characterized by restricted fungal growth associated with rapid localised plant cell death (hypersensitive reaction – HR). Salicylic acid (SA), abscisic acid (ABA) and jasmonic acid (JA) are known to be plant hormones that play a crucial role in controlling plant growth, development, and response to biotic and abiotic cues. It has been suggested that crosstalk occur among JA, SA and ABA in plant response to biological threats. The reduced concentrations of these compounds in complex samples, as it is the case of coffee leaves, requires the optimization of sample preparation techniques and the use of sensitive and selective techniques for their quantification. In order to examine the possible association of the SA, ABA and JA with the resistance response, Coffea arabica S4 Agaro leaves were inoculated with race II of H. vastatrix (incompatible interaction) and extracts were obtained at various times after inoculation. Initially, we made the optimization and validation of the method for analysis of SA, JA and ABA, by HPLC-MS/MS in leaf samples of healthy coffee. We evaluated several methods of sample preparation, all based on liquid-liquid extractions. For a better sensitivity and selectivity a MRM mode was used for the quantification, using the best transitions obtained for each compound. The optimized HPLC-MS/MS method seems adequate for the separation and quantification of SA, ABA and JA in the extracts. Cytological study of infection process of the fungus, allowed identifying the different phases of differentiation of H. vastatrix, before and after penetrations in leaf tissue. In the incompatible interaction there was an initial increase of concentration for all compounds between 20h-30 hours after inoculation (h.a.i.) which leads us to consider their involvement in the hypersensitivity reaction. There was a second increase, only for SA and JA, around 48-72h.a.i., which suggests the possible involved of these compounds in more delayed defense responses. The weak increase of ABA and JA in coffee-rust incompatible interaction, on the contrary to the values obtained for SA, confirmed the assumptions of literature on the signaling action of this compound (SA) against biotrophic pathogens.
Descrição: Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
URI: http://hdl.handle.net/10400.5/3105
Appears in Collections:BISA - Dissertações de Mestrado / Master Thesis

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