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Descripción
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| The plant NADPH oxidases, termed respiratory burst oxidase homologues (RBOHs), produce reactive oxygen species (ROS) which mediate a wide range of functions. Fine tuning this ROS production provides the signaling specificity to the plant cell to produce the appropriate response to environmental threats. RbohD and RbohF, two of the ten Rboh genes present in Arabidopsis, are pleiotropic and mediate diverse physiological processes in response to pathogens. One aspect that may prove critical to determine the multiplicity of functions of RbohD and RbohF is the spatio-temporal control of their gene expression. Thus, we generated Arabidopsis transgenic lines with RbohD- and RbohF-promoter fusions to the ?-glucuronidase and the luciferase reporter genes. These transgenics were employed to reveal RbohD and RbohF promoter activity during Arabidopsis immune response to the pathogenic bacterium Pseudomonas syringae pv tomato DC3000, the necrotrophic fungus Plectosphaerella cucumerina and in response to immunity-related cues. Our experiments revealed a differential expression pattern of RbohD and RbohF throughout plant development and during Arabidopsis immune response. Moreover, we observed a correlation between the level of RbohD and RbohF promoter activity, the accumulation of ROS and the amount of cell death in response to pathogens. RbohD and RbohF gene expression was also differentially modulated by pathogen associated molecular patterns and abscisic acid. Interestingly, a promoter-swap strategy revealed the requirement for the promoter region of RbohD to drive the production of ROS in response to P. cucumerina. Additionally, since the RbohD promoter was activated during Arabidopsis interaction with the non-adapted P. cucumerina isolate 2127, we performed susceptibility tests with this fungal isolate that uncovered a new role of these oxidases on non-host resistance. The interplay between RBOH-dependent signaling with other components of the plant immune response might also explain the different immunity-related functions mediated by these oxidases. Among the plethora of signals coordinated with RBOH activity, pharmacological and genetic evidences indicate that heterotrimeric G proteins, are involved in some of the signaling pathways mediated by RBOH?derived ROS in response to environmental cues. Therefore, we analysed the interplay between these RBOH-NADPH oxidases and AGB1, the Arabidopsis ?-subunit of heterotrimeric G proteins during Arabidopsis immune response. | |
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Internacional
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Si |
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ISBN
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Tipo de Tesis
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Doctoral |
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Calificación
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Sobresaliente cum laude |
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Fecha
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19/06/2015 |