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Descripción
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| Incompatible interactions between plant and pathogen are often determined by the hypersensitive reaction (HR).This response is associated with accumulation of reactive oxygen species (ROS) , which results in adverse growth conditions for microorganisms. Two major mechanisms involving either NADPH oxidases or peroxidases have been proposed for the generation of ROS. Plant peroxidases (PER, EC 1.11.1.7) are present in all land plants. They are members of a large multigenic family with high number of isoforms involved in a broad range of physiological processes. The pathogen-inducible PER have been categorized into the PR-9 family of pathogenesis-related proteins(PR). Peroxidase genes that are expressed in nematode feeding sites have been identified in several plant species. PER isozymes induction in roots of hexaploid wheat (Triticum aestivum) line H-93-8 carrying Heterodera avenae resistance gene Cre2 was detected by isoelectrofocusing (IEF) in response to nematode infection. New bands or increased activities of existing isoforms were identified in infected H-93-8 line in comparison to uninfected control. In order to qualitatively analyse these changes, RNAs were extracted from leaves and roots, four and seven days after infection. First strand cDNAs were obtained and used for 5¿- and 3¿-RACE reactions with peroxidase specific primers. Sequence data from overlapping cDNA clones were aligned according to similarity and classified in six groups: POX1, POX2, POX3, POX4, pr1OS and putativeOs . The last two groups are different from PER previously described in wheat, but show high homology to two distinct PER groups from rice genome. Comparative analyses of deduced amino acid sequences revealed that they contain conserved structural features and activity sites typical of plant PER, such as predicted ER-targeting N-terminal propeptides (NTPP), catalytic center distal heme-binding domain (Hd) and proximal heme-binding domain (Hp). Quantitative expression of distinct PER groups, during Heterodera avenae attack, was assessed by qRT-PCR technique. We found that PER were predominantly expressed in roots, with lower levels of transcripts in both infected and uninfected leaves. The PER groups POX1, POX2 and POX3 showed induction during pathogen attack, mainly detectable at four days post-inoculation. The POX1 have a high identity to TmPRX1 (AY857755, 80%), a Blumeria graminis inducible PER gene isolated from Triticum monococcum leaves. Not only, POX2 and POX3 showed very high identity (86%) with each other, but also were very similar to another PER up-regulated by powdery mildew infection in bread wheat. | |
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Internacional
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Si |
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Nombre congreso
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6 Plant Genomics European Meeting |
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Tipo de participación
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960 |
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Lugar del congreso
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Tenerife, España |
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Revisores
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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03/10/2007 |
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Fecha fin congreso
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06/10/2007 |
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