Catálogo de publicaciones - libros

Salicylic acid triggers is the system for acquired resistance to phytopathogens and hypersensitive cell death of infected cells. It was shown that in "sick" plants salicylic acid induced protective response, caused by increasing the level of multiple local reactive oxygen species with the participation of oxalate oxidase and also lignification of pathogen penetration zone by involving peroxidase. The localization of oxidative burst leads to the death of pathogen and isolation of host infected tissues that were provided with "chitin-specificity" of these enzymes. Induction of activity of wheat "chitin-specific" oxalateoxidase and anionic peroxidase, intensification of their secretion into intercellular space under salicylic acid influence, that provides successful defense reactions, close to pathogen infection structures have been revealed.

Salicylic acid (SA) plays an important role in plant defense. Its role in plant disease resistance is well documented for dicotyledonous plants, where it is required for basal resistance against pathogens as well as for the inducible defense mechanism, systemic acquired resistance (SAR), which confers resistance against a broad-spectrum of pathogens. The activation of SAR is associated with the heightened level of expression of the pathogenesis-related proteins, some of which possess antimicrobial activity. Studies in the model plant have provided important insights into the mechanism of SA signaling in plant defense. The NPR1 protein is an important component of SA signaling in Arabidopsis. Homologues of NPR1 are present in other plant species. NPR1 is also required for plant defense mechanisms that do not require SA. Hence, NPR1 provides an important link between different defense mechanisms. Similarly, cross talk between SA and other defense signaling pathways results in the fine-tuning of plant defense response. Recent discoveries have implicated an important role for lipids in SA signaling. We discuss the progress made in understanding SA biosynthesis and signaling, its cross talk with other mechanisms in plant defense and the practical utility in targeting this defense mechanism for enhancing disease resistance.

Tobacco has played historically important role in the discovery and functional analysis of salicylic acid (SA) as a plant hormone. Using this model, it was demonstrated for the first time that tobacco mosaic virus (TMV) infection results in the accumulation of SA in infected tissues that is to activate local and systemic expression of pathogenesis-related proteins in the cells. Furthermore, SA has been shown to function as a major factor in the development of systemic acquired resistance (SAR) in plants. To promote the importance of tobacco as a model plant, we generated and sequenced cDNA libraries from tobacco BY-2 cells, depositing about 20,000 EST sequence information in the public databases. Selected cDNA clones were then used to prepare the first large-scale 16K microarray of tobacco. In this chapter, we describe our results of a large scale gene expression analysis, using the tobacco BY-2 cells, treated with a 40 μM salicylic acid. In total, 376 genes (corresponding to individual ESTs) were at least 2-fold upregulated by SA, relative to their expression levels in control cells. Amid, a large number of genes overlapped with known defense-related genes in plants, whilst the others represented novel targets of SA in plants. The kinetic analysis of the SA-responsive genes, together with functional analysis of these genes in the plant defense, is presented in this chapter.