Publicações

@article{Nascimento2022,

title = {Overexpression of CsSAMT in Citrus sinensis Induces Defense Response and Increases Resistance to Xanthomonas citri subsp. citri},

author = {Cesar Augusto Nascimento and Natalia Sousa Teixeira-Silva and Raquel Caserta and Marcia Ortiz Mayo Marques and Marco Aurelio Takita and Alessandra A. Souza},

doi = {10.3389/FPLS.2022.836582/BIBTEX},

issn = {1664462X},

year  = {2022},

date = {2022-01-01},

journal = {Frontiers in Plant Science},

volume = {13},

pages = {820},

publisher = {Frontiers Media S.A.},

abstract = {Citrus canker is a destructive disease caused by Xanthomonas citri subsp. citri, which affects all commercial sweet orange (Citrus sinensis [L.] Osbeck) cultivars. Salicylic acid (SA) and systemic-acquired resistance (SAR) have been demonstrated to have a crucial role in mediating plant defense responses against this phytopathogen. To induce SAR, SA is converted to methyl salicylate (MeSA) by an SA-dependent methyltransferase (SAMT) and translocated systemically to prime noninfected distal tissues. Here, we generated sweet orange transgenic plants (based on cvs. Hamlin and Valencia) overexpressing the SAMT gene from Citrus (CsSAMT) and evaluated their resistance to citrus canker. We obtained four independent transgenic lines and confirmed their significantly higher MeSA volatilization compared to wild-type controls. Plants overexpressing CsSAMT showed reduced symptoms of citrus canker and bacterial populations in all transgenic lines without compromising plant development. One representative transgenic line (V44SAMT) was used to evaluate resistance response in primary and secondary sites. Without inoculation, V44SAMT modulated CsSAMT, CsNPR1, CsNPR3, and CsWRKY22 expression, indicating that this plant is in a primed defense status. The results demonstrate that MeSA signaling prompts the plant to respond more efficiently to pathogen attacks and induces immune responses in transgenic plants at both primary and secondary infection sites.},

keywords = {Citrus canker, MeSA, Methyl salicylate, Salicylic acid, systemic-acquired resistance},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Overexpression of Citrus reticulata SAMT in Nicotiana tabacum increases MeSA volatilization and decreases Xylella fastidiosa symptoms},

author = {Laura M. Gómez and Natália S. Teixeira-Silva and Raquel Caserta and Marco A. Takita and Márcia O. M. Marques and Alessandra A. Souza},

url = {https://link.springer.com/article/10.1007/s00425-020-03511-1},

doi = {10.1007/S00425-020-03511-1/METRICS},

issn = {14322048},

year  = {2020},

date = {2020-01-01},

journal = {Planta},

volume = {252},

issue = {6},

pages = {1-14},

publisher = {Springer Science and Business Media Deutschland GmbH},

abstract = {Main conclusion: Nicotiana tabacum overexpressing CrSAMT from Citrus reticulata increased production of MeSA, which works as an airborne signal in neighboring wild-type plants, inducing PR1 and increasing resistance to the pathogen Xylella fastidiosa. Abstract: Xylella fastidiosa is one of the major threats to plant health worldwide, affecting yield in many crops. Despite many efforts, the development of highly productive resistant varieties has been challenging. In studying host plant resistance, the S-adenosyl-l-methionine: salicylic acid carboxyl methyltransferase gene (SAMT) from Citrus reticulata, a X. fastidiosa resistant species, was upregulated in response to pathogen infection. SAMT is involved with the catalysis and production of methyl salicylate (MeSA), an airborne signal responsible for triggering systemic acquired resistance. Here we used tobacco as a model system and generated transgenic plants overexpressing C. reticulata SAMT (CrSAMT). We performed an in silico structural characterization of CrSAMT and investigated its biotechnological potential in modulating the immune system in transgenic plants. The increase of MeSA production in transgenic lines was confirmed by gas chromatography (GC–MS). The transgenic lines showed upregulation of PR1, and their incubation with neighboring wild-type plants activated PR1 expression, indicating that MeSA worked as an airborne signal. In addition, transgenic plants showed significantly fewer symptoms when challenged with X. fastidiosa. Altogether, these data suggest that CrSAMT plays a role in host defense response and can be used in biotechnology approaches to confer resistance against X. fastidiosa.},

keywords = {Methyl salicylate, Model plant, Salicylic acid, Salicylic acid methyltransferase, Systemic acquired resistance (SAR), Transgenic tobacco},

pubstate = {published},

tppubtype = {article}

}

@article{Arena2020,

title = {Plant Immune System Activation Upon Citrus Leprosis Virus C Infection Is Mimicked by the Ectopic Expression of the P61 Viral Protein},

author = {Gabriella D. Arena and Pedro Luis Ramos-González and Bryce W. Falk and Clare L. Casteel and Juliana Freitas-Astúa and Marcos A. Machado},

doi = {10.3389/FPLS.2020.01188/BIBTEX},

issn = {1664462X},

year  = {2020},

date = {2020-01-01},

journal = {Frontiers in Plant Science},

volume = {11},

pages = {1188},

publisher = {Frontiers Media S.A.},

abstract = {Citrus leprosis virus C (CiLV-C, genus Cilevirus, family Kitaviridae) is an atypical virus that does not spread systemically in its plant hosts. Upon its inoculation by Brevipalpus mites, only localized lesions occur, and the infection remains limited to cells around mite feeding sites. Here, we aimed to gain insights into the putative causes of viral unfitness in plants by expanding the limited knowledge of the molecular mechanisms underlying plant/kitavirid interactions. Firstly, we quantified the CiLV-C viral RNAs during the infection in Arabidopsis thaliana plants using RT-qPCR and systematized it by defining three stages of distinguishing subgenomic and genomic RNA accumulation: i) 0–24 h after infestation, ii) 2–4 days after infestation (dai), and iii) 6–10 dai. Accordingly, the global plant response to CiLV-C infection was assessed by RNA-Seq at each period. Results indicated a progressive reprogramming of the plant transcriptome in parallel to the increasing viral loads. Gene ontology enrichment analysis revealed the induction of cell growth-related processes at the early stages of the infection and the triggering of the SA-mediated pathway, ROS burst and hypersensitive response (HR) at the presymptomatic stage. Conversely, infected plants downregulated JA/ET-mediated pathways and processes involved in the primary metabolism including photosynthesis. Marker genes of unfolded protein response were also induced, suggesting a contribution of the endoplasmic reticulum stress to the cell death caused by the viral infection. Finally, we transiently expressed CiLV-C proteins in Nicotiana benthamiana plants to undertake their roles in the elicited plant responses. Expression of the CiLV-C P61 protein consistently triggered ROS burst, upregulated SA- and HR-related genes, increased SA levels, reduced JA levels, and caused cell death. Mimicry of responses typically observed during CiLV-C–plant interaction indicates P61 as a putative viral effector causing the HR-like symptoms associated with the infection. Our data strengthen the hypothesis that symptoms of CiLV-C infection might be the outcome of a hypersensitive-like response during an incompatible interaction. Consequently, the locally restricted infection of CiLV-C, commonly observed across infections by kitavirids, supports the thesis that these viruses, likely arising from an ancestral arthropod-infecting virus, are unable to fully circumvent plant defenses.},

keywords = {Arabidopsis thaliana, Cilevirus, hypersensitive response, Jasmonic acid, Nicotiana benthamiana, plant–virus interaction, RNA-Seq, Salicylic acid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Overexpression of Citrus reticulata SAMT in Nicotiana tabacum increases MeSA volatilization and decreases Xylella fastidiosa symptoms},

author = {Laura M. Gómez and Natália S. Teixeira-Silva and Raquel Caserta and Marco A. Takita and Márcia O. M. Marques and Alessandra A. Souza},

url = {https://link.springer.com/article/10.1007/s00425-020-03511-1},

doi = {10.1007/S00425-020-03511-1/METRICS},

issn = {14322048},

year  = {2020},

date = {2020-01-01},

journal = {Planta},

volume = {252},

issue = {6},

pages = {1-14},

publisher = {Springer Science and Business Media Deutschland GmbH},

abstract = {Main conclusion: Nicotiana tabacum overexpressing CrSAMT from Citrus reticulata increased production of MeSA, which works as an airborne signal in neighboring wild-type plants, inducing PR1 and increasing resistance to the pathogen Xylella fastidiosa. Abstract: Xylella fastidiosa is one of the major threats to plant health worldwide, affecting yield in many crops. Despite many efforts, the development of highly productive resistant varieties has been challenging. In studying host plant resistance, the S-adenosyl-l-methionine: salicylic acid carboxyl methyltransferase gene (SAMT) from Citrus reticulata, a X. fastidiosa resistant species, was upregulated in response to pathogen infection. SAMT is involved with the catalysis and production of methyl salicylate (MeSA), an airborne signal responsible for triggering systemic acquired resistance. Here we used tobacco as a model system and generated transgenic plants overexpressing C. reticulata SAMT (CrSAMT). We performed an in silico structural characterization of CrSAMT and investigated its biotechnological potential in modulating the immune system in transgenic plants. The increase of MeSA production in transgenic lines was confirmed by gas chromatography (GC–MS). The transgenic lines showed upregulation of PR1, and their incubation with neighboring wild-type plants activated PR1 expression, indicating that MeSA worked as an airborne signal. In addition, transgenic plants showed significantly fewer symptoms when challenged with X. fastidiosa. Altogether, these data suggest that CrSAMT plays a role in host defense response and can be used in biotechnology approaches to confer resistance against X. fastidiosa.},

keywords = {Methyl salicylate, Model plant, Salicylic acid, Salicylic acid methyltransferase, Systemic acquired resistance (SAR), Transgenic tobacco},

pubstate = {published},

tppubtype = {article}

}

@article{Arena2018,

title = {Making a better home: modulation of plant defensive response by brevipalpus mites},

author = {Gabriella D. Arena and Pedro L. Ramos-González and Luana A. Rogerio and Marcelo Ribeiro-Alves and Clare L. Casteel and Juliana Freitas-Astúa and Marcos A. Machado},

doi = {10.3389/FPLS.2018.01147/BIBTEX},

issn = {1664462X},

year  = {2018},

date = {2018-01-01},

journal = {Frontiers in Plant Science},

volume = {9},

pages = {1147},

publisher = {Frontiers Media S.A.},

abstract = {False-spider mites of the genus Brevipalpus are highly polyphagous pests that attack hundreds of plant species of distinct families worldwide. Besides causing direct damage, these mites may also act as vectors of many plant viruses that threaten high-value ornamental plants like orchids and economically important crops such as citrus and coffee. To better understand the molecular mechanisms behind plant-mite interaction we used an RNA-Seq approach to assess the global response of Arabidopsis thaliana (Arabidopsis) plants along the course of the infestation with Brevipalpus yothersi, the main vector species within the genus. Mite infestation triggered a drastic transcriptome reprogramming soon at the beginning of the interaction and throughout the time course, deregulating 1755, 3069 and 2680 genes at 6 hours after infestation (hai), 2 days after infestation (dai), and 6 dai, respectively. Gene set enrichment analysis revealed a clear modulation of processes related to the plant immune system. Co-expressed genes correlated with specific classes of transcription factors regulating defense pathways and developmental processes. Up-regulation of defensive responses correlated with the down-regulation of growth-related processes, suggesting the triggering of the growth-defense crosstalk to optimize plant fitness. Biological processes (BPs) enriched at all time points were markedly related to defense against herbivores and other biotic stresses involving the defense hormones salicylic acid (SA) and jasmonic acid (JA). Levels of both hormones were higher in plants challenged with mites than in the non-infested ones, supporting the simultaneous induction of genes from both pathways. To further clarify the functional relevance of the plant hormonal pathways on the interaction, we evaluated the mite performance on Arabidopsis mutants impaired in SA- or JA-mediated response. Mite oviposition was lower on mutants defective in SA biosynthesis (sid2) and signaling (npr1), showing a function for SA pathway in improving the mite reproduction, an unusual mechanism compared to closely-related spider mites. Here we provide the first report on the global and dynamic plant transcriptome triggered by Brevipalpus feeding, extending our knowledge on plant-mite interaction. Furthermore, our results suggest that Brevipalpus mites manipulate the plant defensive response to render the plant more susceptible to their colonization by inducing the SA-mediated pathway.},

keywords = {Cross-talk, Defense pathways, Jasmonic acid, Plant hormones, Plant–herbivore interaction, RNA-Seq, Salicylic acid, Tetranychus},

pubstate = {published},

tppubtype = {article}

}