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| Author(s): |
Simone Cespedes Vitor
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2013-02-20 |
| Examining board members: |
Ione Salgado;
Marcelo Menossi;
Marilia Gaspar
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| Advisor: | Ione Salgado |
| Abstract | |
NO is an important signaling and versatile molecule which plays important roles in many processes in plants. One of its main actions is in cell signaling during defense response against pathogen attack. Arabidopsis thaliana plants of the nia1 nia2 mutant genotype, deficient in the two structural genes encoding for the enzyme nitrate reductase (NR), are susceptible to the avirulent bacteria Pseudomonas syringae. It has been suggested that the impaired defense response in the NR-deficient mutant would result from their low NO levels when compared to those of the wild type. Indeed, in a recent study from our group, it was observed through a DNA microarray that fumigation of nia1 nia2 mutant with NO gas was able to modulate many genes related to defense, some of which not previously documented as responsive to this radical. In this work we analyzed by real-time PCR the effect of NO gas on the expression of genes related to defense in the wild type and nia1 nia2 mutant infected with an avirulent strain of Pseudomonas syringae. Defense genes such as PR1 were induced by the bacteria and its expression was higher in wild type when compared to nia1 nia2, which is consistent with the susceptibility of the mutant. NO fumigation also modulated genes related to the biosynthesis of lignin (CAD1) and the auxin (Tir1, ILL1, GH3) and ethylene pathways (ACCS7). Analysis of lignin showed a reduction of this compound in the mutant genotype compared to wild type, and a difference in its composition. In addition, fumigation with NO attenuated the expression of PR1 and other genes related to salicylic acid signaling in infected plants and prevented bacterial growth in nia1 nia2 leaves. Furthermore, pathogen infection is known to induce a low production of NO in nia1 nia2 and here we also observed that there is a higher production of H2O2 in the mutant compared to the wild type. H2O2 potentiated the microbicidal effect of NO fumigated in bacterial suspensions. The results suggest that a direct microbicidal effect of NO, together with H2O2, may result in attenuation of the defense response in the plant, reducing energy expenditure associated with the transcription of genes related to defense (AU) | |
| FAPESP's process: | 11/02465-5 - Analysis of gene expression and production of secondary metabolites induced by nitric oxide in the defense response of Arabidopsis thaliana to Pseudomonas syringae |
| Grantee: | Simone Cespedes Vitor |
| Support Opportunities: | Scholarships in Brazil - Master |