Browsing by Author "Fuenzalida Valdivia, Isabel Cristina"

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    Molecular and Genomic Characterization of the Pseudomonas syringae Phylogroup 4: An Emerging Pathogen of Arabidopsis thaliana and Nicotiana benthamiana
    (MDPI, 2022) Zavala, Diego; Fuenzalida Valdivia, Isabel Cristina; Gangas, Maria Victoria; Margutti, Micaela Peppino; Bartoli, Claudia; Roux, Fabrice; Meneses Araya, Claudio Antonio; Herrera Vásquez, Ariel Esteban; Blanco Herrera, María Francisca
    Environmental fluctuations such as increased temperature, water availability, and air CO2 concentration triggered by climate change influence plant disease dynamics by affecting hosts, pathogens, and their interactions. Here, we describe a newly discovered Pseudomonas syringae strain found in a natural population of Arabidopsis thaliana collected from the southwest of France. This strain, called Psy RAYR-BL, is highly virulent on natural Arabidopsis accessions, Arabidopsis model accession Columbia 0, and tobacco plants. Despite the severe disease phenotype caused by the Psy RAYR-BL strain, we identified a reduced repertoire of putative Type III virulence effectors by genomic sequencing compared to P. syringae pv tomato (Pst) DC3000. Furthermore, hopBJ1(Psy) is found exclusively on the Psy RAYR-BL genome but not in the Pst DC3000 genome. The plant expression of HopBJ1(Psy) induces ROS accumulation and cell death. In addition, HopBJ1(Psy) participates as a virulence factor in this plant-pathogen interaction, likely explaining the severity of the disease symptoms. This research describes the characterization of a newly discovered plant pathogen strain and possible virulence mechanisms underlying the infection process shaped by natural and changing environmental conditions.
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    The Negative Regulators of the Basal Defence WRKY7, WRKY11 and WRKY17 Modulate the Jasmonic Acid Pathway and an Alternative Splicing Regulatory Network in Response to Pseudomonas syringae in Arabidopsis thaliana
    (2024) Fuenzalida Valdivia, Isabel Cristina; Herrera Vásquez, Ariel Esteban; Gangas, Maria Victoria; Saez-Vasquez, Julio; Alvarez, José Miguel; Meneses Araya, Claudio Antonio; Blanco Herrera, María Francisca
    In Arabidopsis thaliana, the transcription factors WRKY7, WRKY11 and WRKY17 act as negative defence regulators against Pseudomonas syringae pv. tomato (Pst) DC3000. However, their coordinated regulation of gene expression has yet to be fully explored. In this study, we conducted a transcriptomic analysis on the triple mutant wrky7/11/17 in response to Pst DC3000 at 0, 3 and 24h post-inoculation (hpi). Our results suggest that at early infection stages (0 and 3 hpi), WRKY7, WRKY11 and WRKY17 significantly repress a group of genes involved in signal perception and transduction, including receptor-like kinases. Furthermore, at later stages of interaction (24 hpi), these transcription factors induce genes related to the biosynthesis and signalling of the jasmonic acid (JA) pathway. Further infection experiments with Pst DC3000 in plants treated with methyl jasmonate (a JA analogue) and infections with Botrytis cinerea, a pathogen against which JA-mediated responses are crucial for effective defence, support this proposal. Moreover, we analysed the role of WRKY7, WRKY11 and WRKY17 in alternative splicing regulation. A comparison between differentially expressed (DEG) and spliced (DAS) genes revealed that over 80% of DAS events do not occur in conjunction with overall changes in gene expression. Alternative splicing events were found in genes with functions in splicing and the JA pathway, such as ALY4, PRP40A, JAZ3 and JAZ10. These results suggest that WRKY7, WRKY11 and WRKY17 can also participate in this layer of gene expression regulation to modulate immunity negatively