Publications

@article{Dilarri2022,

title = {Evaluation of calcium hydroxide, calcium hypochlorite, peracetic acid, and potassium bicarbonate as citrus fruit sanitizers},

author = {Guilherme Dilarri and Caio Felipe Cavicchia Zamuner and Mauricio Bacci and Henrique Ferreira},

url = {https://link.springer.com/article/10.1007/s13197-021-05185-3},

doi = {10.1007/S13197-021-05185-3/METRICS},

issn = {09758402},

year  = {2022},

date = {2022-01-01},

journal = {Journal of Food Science and Technology},

volume = {59},

issue = {5},

pages = {1739-1747},

publisher = {Springer},

abstract = {Xanthomonas citri (X. citri) is a quarentenary plant pathogen and the causal agent of the citrus canker. X. citri forms biofilms and remains fixed on the surface of plant tissues, especially on leaves and fruits. Considering this, all the citrus fruits have to be sanitized before they can be commercialized. NaOCl is the main sanitizer used to decontaminate fruits in the world. Due to its toxicity, treatment with NaOCl is no longer accepted by some Europe Union countries. Therefore, the aim of this work was to evaluate potassium bicarbonate (KHCO3), calcium hydroxide (Ca(OH)2), calcium hypochlorite (Ca(OCl)2) and peracetic acid (CH3CO3H) as alternatives to NaOCl for the sanitization of citrus fruit. By monitoring cell respiration and bacterial growth, we determined that peracetic acid and calcium hypochlorite exhibit bactericidal action against X. citri. Time-response growth curves and membrane integrity analyses showed that peracetic acid and calcium hypochlorite target the bacterial cytoplasmatic membrane, which is probably responsible for cell death in the first minutes of contact. The simulation of the sanitization process of citrus fruit in packinghouses showed that only peracetic acid exhibited a performance comparable to NaOCl. Among the tested compounds, peracetic acid constitutes an efficient and safer alternative to NaOCl.},

keywords = {Citrus canker, Orange, Packinghouse, Post-harvest sanitization, Sodium hypochlorite, Xanthomonas citri subsp. citri},

pubstate = {published},

tppubtype = {article}

}

@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{Bueno2021,

title = {Riboswitch theo/metE as a Transcription Regulation Tool for Xanthomonas citri subsp. citri},

author = {Danilo Bueno and Danielle B. Pedrolli and Paula M. M. Martins and Daniela A. Bocchini and Karen C. M. Moraes and Agda P. Facincani and Jesus A. Ferro and Alessandro M. Varani and Michelle M. Pena and Henrique Ferreira},

url = {https://www.mdpi.com/2076-2607/9/2/329/htm https://www.mdpi.com/2076-2607/9/2/329},

doi = {10.3390/MICROORGANISMS9020329},

issn = {2076-2607},

year  = {2021},

date = {2021-01-01},

journal = {Microorganisms 2021, Vol. 9, Page 329},

volume = {9},

issue = {2},

pages = {329},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Xanthomonas citri subsp. citri (X. citri) is the causal agent of Asiatic Citrus Canker (ACC), a disease that affects citrus. ACC has no cure, and growers must rely on special agricultural practices to prevent bacterial spreading. Understanding X. citri basic biology is essential to foresee potential genetic targets to control ACC. Traditionally, microbial genetics use gene deletion/disruption to investigate gene function. However, essential genes are difficult to study this way. Techniques based on small-RNAs and antisense-RNAs are powerful for gene characterization, but not yet fully explored in prokaryotes. One alternative is riboswitches, which derive from bacteria, and can control transcription/translation. Riboswitches are non-coding RNAs able to modulate gene expression in the presence of specific ligands. Here we demonstrate that the riboswitch theo/metE decreases parB expression in X. citri in a platform responsive to theophylline. By monitoring cell respiration, we showed that higher concentrations of the ligand interfered with bacterial viability. Therefore, we determined the safe dose of theophylline to be used with X. citri. Finally, in downstream investigations of parB transcription modulation, we show evidence for the fact that ParB is stable, remains functional throughout the cell cycle, and is inherited by the daughter cells upon cell division.},

keywords = {<i>parB</i>, Chromosome segregation, Citrus canker, pNPTS138 sequence, regulation of gene expression},

pubstate = {published},

tppubtype = {article}

}

@article{Martins2021,

title = {Persister Cells Form in the Plant Pathogen Xanthomonas citri subsp. citri under Different Stress Conditions},

author = {Paula M. M. Martins and Thomas K. Wood and Alessandra A. Souza},

url = {https://www.mdpi.com/2076-2607/9/2/384/htm https://www.mdpi.com/2076-2607/9/2/384},

doi = {10.3390/MICROORGANISMS9020384},

issn = {2076-2607},

year  = {2021},

date = {2021-01-01},

journal = {Microorganisms 2021, Vol. 9, Page 384},

volume = {9},

issue = {2},

pages = {384},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Citrus canker disease, caused by the bacterium Xanthomonas citri subsp. citri is a constant threat to citrus-producing areas. Since it has no cure, agricultural practices to restrain its dissemination are essential to reduce the economic damage. Hence, increased knowledge of the basic aspects of X. citri biology could lead to more efficient management practices that can eliminate dormant bacteria in the field. The dormant cells, also referred to as persisters, are phenotypic variants with lowered metabolism, which in turn leads to tolerance to antimicrobials and undermines existing control approaches. We show here that X. citri forms persisters, identifying triggers for this phenotype, including antibiotics, high temperature, and metals (copper and zinc), which increase persistence rates by 10–100 times. The antioxidant N-acetylcysteine reduced copper and zinc-induced persisters, but not those induced by tetracycline, indicating that oxidative stress may be an important inducer of X. citri persistence. In addition, we found that metabolism-independent drugs like cisplatin and mitomycin C are able to eliminate X. citri persistent cells, as well as copper, at high concentrations. Specific amino acids like proline and isoleucine interfered with the physiological balance of the dormancy in X. citri, stimulating or preventing persister resuscitation. Taken together, we discover chemicals that can induce, wake, and kill X. citri persister cells; these results provide insights that should be considered for more efficient integrated control management in the field.},

keywords = {Citrus, Citrus canker, persistence, Phytopathogen},

pubstate = {published},

tppubtype = {article}

}

@article{Mitre2021,

title = {The Arabidopsis immune receptor EFR increases resistance to the bacterial pathogens Xanthomonas and Xylella in transgenic sweet orange},

author = {Letícia Kuster Mitre and Natália Sousa Teixeira-Silva and Katarzyna Rybak and Diogo Maciel Magalhães and Reinaldo Rodrigues Souza-Neto and Silke Robatzek and Cyril Zipfel and Alessandra Alves Souza},

url = {https://onlinelibrary.wiley.com/doi/full/10.1111/pbi.13629 https://onlinelibrary.wiley.com/doi/abs/10.1111/pbi.13629 https://onlinelibrary.wiley.com/doi/10.1111/pbi.13629},

doi = {10.1111/PBI.13629},

issn = {1467-7652},

year  = {2021},

date = {2021-01-01},

journal = {Plant Biotechnology Journal},

volume = {19},

issue = {7},

pages = {1294-1296},

publisher = {John Wiley & Sons, Ltd},

keywords = {associated molecular pattern, broad, Citrus canker, citrus variegated chlorosis, outer membrane vesicle, pathogen, pattern recognition receptor, spectrum disease resistance},

pubstate = {published},

tppubtype = {article}

}

@article{Zamuner2020,

title = {A cinnamaldehyde-based formulation as an alternative to sodium hypochlorite for post-harvest decontamination of citrus fruit},

author = {Caio F. C. Zamuner and Guilherme Dilarri and Lucia C. Bonci and Luiz L. Saldanha and Franklin Behlau and Tamiris G. S. Marin and Daiane C. Sass and Mauricio Bacci and Henrique Ferreira},

url = {https://link.springer.com/article/10.1007/s40858-020-00338-9},

doi = {10.1007/S40858-020-00338-9/METRICS},

issn = {19832052},

year  = {2020},

date = {2020-01-01},

journal = {Tropical Plant Pathology},

volume = {45},

issue = {6},

pages = {701-709},

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

abstract = {According to the most recent regulation, published in 2018, areas or states of Brazil where citrus canker is endemic are no longer obliged to eradicate citrus trees affected by the disease as in the past 60 years. Instead, growers have to adopt a set of control measures, such as copper sprays, windbreaks, and control of the citrus leaf miner to minimize the impact of the disease on fruit quality and yield. Another important change was that all fresh Fruit commercialized out of the state of origin and to other countries have to be sanitized against the canker-causing bacterium Xanthomonas citri subsp. citri (X. citri). Initially, sodium hypochlorite (NaOCl) was the only product allowed in Brazil by the referred legislation. Recently, this bactericide was prohibited to be used on fresh fruit shipped to the European Union and replaced by eugenol at 2%. Although effective, NaOCl may damage fruit skin, cause corrosion of packing house equipment and react with organic matter, which generates noxious by products. Here, we evaluated an alternative to NaOCl known as PosFruit. GC/MS and 1H NMR chemical analyses showed that Posfruit contains both cinnamaldehyde isomers, with the trans being present in larger quantities. We showed that PosFruit was as effective as NaOCl to eliminate X. citri from citrus fruit artificially contaminated with the bacterium. In a pilot sanitization line, treatment with 2% PosFruit reduced the X. citri population on contaminated fruit by 4 log10 CFU/mL. Furthermore, we detect neither the natural resistance of X. citri to PosFruit nor the persistence of the bacterium following progressive exposure to the product, which indicates that the product has multi-target action. PosFruit is a plant fortifier, residue-free, and efficient alternative to NaOCl for post-harvest decontamination of citrus fruit against X. citri.},

keywords = {Citrus canker, Fresh fruit, Sanitization},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Anti-Xanthomonas activity of Antarctic fungi crude extracts},

author = {Juliano Henrique Ferrarezi and Juliana Aparecida Santos and Lara Durães Sette and Henrique Ferreira and Daiane Cristina Sass},

url = {https://academicjournals.org/journal/AJB/article-abstract/A2117D861600},

doi = {10.5897/AJB2019.16886},

issn = {1684-5315},

year  = {2019},

date = {2019-01-01},

journal = {African Journal of Biotechnology},

volume = {18},

issue = {28},

pages = {713-718},

publisher = {Academic Journals},

abstract = {Agriculture suffers considerable losses in its production caused by plant diseases. In the citrus culture some problems were associated with citrus canker caused by Xanthomonas citri subsp. citri. That same way, sugarcane plantations are impaired to leaf scald disease caused by Xanthomonas albilineans. One of the measures used to contain citrus canker is the spray of cupric bactericides; however for scalding leaves there are no satisfactory control. Due to the phytosanitary problem caused by Xanthomonas (X. citri and X. albilineans) and by the difficulty of its control, the search for new forms of defense, less harmful to the environment, has become increasingly required. Thus, the aim of this work was to obtain crude organic extracts from filamentous fungi isolated from Antarctic soil samples and assess its bioactivity potential against X. citri and X. albilineans. One hundred and twenty-two extracts were tested, seven extracts inhibited the cell growth of X. citri, one was bioactive only against X. albilineans and one extract inhibited the cell growth of both bacteria. The bioactive extracts had a mean inhibition value of 96% against both bacteria. The values of MIC90 and MBC of bioactive extracts were also determined; for X. citri the isolate 3.1 Fe presented the lowest values of MIC90 (0.28 mg/mL) and MBC (1.0 mg/mL) and the two bioactive isolates for X. albilineans (1.1-Fe and B-Fe) presented the same values of MIC90 (1.4 mg/mL) and MBC (1.5 mg/mL). The filamentous fungi that produced positive extracts were identified as belonging to the genus Pseudogymnoascus (n=8) and Cladosporium (n=1). The filamentous fungi isolated from Antarctic soil produced compounds with bioactivity against phytopathogens from the Xanthomonas genus. 

 

	  

 

	Key words: Antarctic fungi; antibacterial action; citrus canker; leaf scald; natural extracts. 

 

	 },

keywords = {Antarctic fungi, antibacterial action, Citrus canker, leaf scald, natural extracts},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Anti-Xanthomonas activity of Antarctic fungi crude extracts},

author = {Juliano Henrique Ferrarezi and Juliana Aparecida Santos and Lara Durães Sette and Henrique Ferreira and Daiane Cristina Sass},

url = {https://academicjournals.org/journal/AJB/article-abstract/A2117D861600},

doi = {10.5897/AJB2019.16886},

issn = {1684-5315},

year  = {2019},

date = {2019-01-01},

journal = {African Journal of Biotechnology},

volume = {18},

issue = {28},

pages = {713-718},

publisher = {Academic Journals},

abstract = {Agriculture suffers considerable losses in its production caused by plant diseases. In the citrus culture some problems were associated with citrus canker caused by Xanthomonas citri subsp. citri. That same way, sugarcane plantations are impaired to leaf scald disease caused by Xanthomonas albilineans. One of the measures used to contain citrus canker is the spray of cupric bactericides; however for scalding leaves there are no satisfactory control. Due to the phytosanitary problem caused by Xanthomonas (X. citri and X. albilineans) and by the difficulty of its control, the search for new forms of defense, less harmful to the environment, has become increasingly required. Thus, the aim of this work was to obtain crude organic extracts from filamentous fungi isolated from Antarctic soil samples and assess its bioactivity potential against X. citri and X. albilineans. One hundred and twenty-two extracts were tested, seven extracts inhibited the cell growth of X. citri, one was bioactive only against X. albilineans and one extract inhibited the cell growth of both bacteria. The bioactive extracts had a mean inhibition value of 96% against both bacteria. The values of MIC90 and MBC of bioactive extracts were also determined; for X. citri the isolate 3.1 Fe presented the lowest values of MIC90 (0.28 mg/mL) and MBC (1.0 mg/mL) and the two bioactive isolates for X. albilineans (1.1-Fe and B-Fe) presented the same values of MIC90 (1.4 mg/mL) and MBC (1.5 mg/mL). The filamentous fungi that produced positive extracts were identified as belonging to the genus Pseudogymnoascus (n=8) and Cladosporium (n=1). The filamentous fungi isolated from Antarctic soil produced compounds with bioactivity against phytopathogens from the Xanthomonas genus. 

 

	  

 

	Key words: Antarctic fungi; antibacterial action; citrus canker; leaf scald; natural extracts. 

 

	 },

keywords = {Antarctic fungi, antibacterial action, Citrus canker, leaf scald, natural extracts},

pubstate = {published},

tppubtype = {article}

}

@article{Shimo2019,

title = {Role of the Citrus sinensis RNA deadenylase CsCAF1 in citrus canker resistance},

author = {Hugo Massayoshi Shimo and Carolina Terassi and Caio Cesar Lima Silva and Jackeline Lima Zanella and Gustavo Fernando Mercaldi and Silvana Aparecida Rocco and Celso Eduardo Benedetti},

url = {https://onlinelibrary.wiley.com/doi/full/10.1111/mpp.12815 https://onlinelibrary.wiley.com/doi/abs/10.1111/mpp.12815 https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/mpp.12815},

doi = {10.1111/MPP.12815},

issn = {1364-3703},

year  = {2019},

date = {2019-01-01},

journal = {Molecular Plant Pathology},

volume = {20},

issue = {8},

pages = {1105-1118},

publisher = {John Wiley & Sons, Ltd},

abstract = {Poly(A) tail shortening is a critical step in messenger RNA (mRNA) decay and control of gene expression. The carbon catabolite repressor 4 (CCR4)-associated factor 1 (CAF1) component of the CCR4-NOT deadenylase complex plays an essential role in mRNA deadenylation in most eukaryotes. However, while CAF1 has been extensively investigated in yeast and animals, its role in plants remains largely unknown. Here, we show that the Citrus sinensis CAF1 (CsCAF1) is a magnesium-dependent deadenylase implicated in resistance against the citrus canker bacteria Xanthomonas citri. CsCAF1 interacted with proteins of the CCR4-NOT complex, including CsVIP2, a NOT2 homologue, translin-associated factor X (CsTRAX) and the poly(A)-binding proteins CsPABPN and CsPABPC. CsCAF1 also interacted with PthA4, the main X. citri effector required for citrus canker elicitation. We also present evidence suggesting that PthA4 inhibits CsCAF1 deadenylase activity in vitro and stabilizes the mRNA encoded by the citrus canker susceptibility gene CsLOB1, which is transcriptionally activated by PthA4 during canker formation. Moreover, we show that an inhibitor of CsCAF1 deadenylase activity significantly enhanced canker development, despite causing a reduction in PthA4-dependent CsLOB1 transcription. These results thus link CsCAF1 with canker development and PthA4-dependent transcription in citrus plants.},

keywords = {associated factor, CCR4, Citrus canker, Citrus sinensis, CsCAF1, CsLOB1, NOT, PthA4, RNA deadenylase activity, TAL effectors, Xanthomonas aurantifolii, Xanthomonas citri},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Design of Antibacterial Agents: Alkyl Dihydroxybenzoates against Xanthomonas citri subsp. citri},

author = {Ana Carolina Nazaré and Carlos Roberto Polaquini and Lúcia Bonci Cavalca and Daiane Bertholin Anselmo and Marilia Freitas Calmon Saiki and Diego Alves Monteiro and Aleksandra Zielinska and Paula Rahal and Eleni Gomes and Dirk Jan Scheffers and Henrique Ferreira and Luis Octavio Regasini},

url = {https://www.mdpi.com/1422-0067/19/10/3050/htm https://www.mdpi.com/1422-0067/19/10/3050},

doi = {10.3390/IJMS19103050},

issn = {1422-0067},

year  = {2018},

date = {2018-01-01},

journal = {International Journal of Molecular Sciences 2018, Vol. 19, Page 3050},

volume = {19},

issue = {10},

pages = {3050},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Xanthomonas citri subsp. citri (Xcc) causes citrus canker, affecting sweet orange-producing areas around the world. The current chemical treatment available for this disease is based on cupric compounds. For this reason, the objective of this study was to design antibacterial agents. In order to do this, we analyzed the anti-Xcc activity of 36 alkyl dihydroxybenzoates and we found 14 active compounds. Among them, three esters with the lowest minimum inhibitory concentration values were selected; compounds 4 (52 μM), 16 (80 μM) and 28 (88 μM). Our study demonstrated that alkyl dihydroxybenzoates cause a delay in the exponential phase. The permeability capacity of alkyl dihydroxybenzoates in a quarter of MIC was compared to nisin (positive control). Compound 28 was the most effective (93.8), compared to compound 16 (41.3) and compound 4 (13.9) by percentage values. Finally, all three compounds showed inhibition of FtsZ GTPase activity, and promoted changes in protofilaments, leading to depolymerization, which prevents bacterial cell division. In conclusion, heptyl dihydroxybenzoates (compounds 4, 16 and 28) are promising anti-Xcc agents which may serve as an alternative for the control of citrus canker.},

keywords = {Antimicrobial, Citrus canker, membrane disruption, phenolic acids, plant disease},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Design of Antibacterial Agents: Alkyl Dihydroxybenzoates against Xanthomonas citri subsp. citri},

author = {Ana Carolina Nazaré and Carlos Roberto Polaquini and Lúcia Bonci Cavalca and Daiane Bertholin Anselmo and Marilia Freitas Calmon Saiki and Diego Alves Monteiro and Aleksandra Zielinska and Paula Rahal and Eleni Gomes and Dirk Jan Scheffers and Henrique Ferreira and Luis Octavio Regasini},

url = {https://www.mdpi.com/1422-0067/19/10/3050/htm https://www.mdpi.com/1422-0067/19/10/3050},

doi = {10.3390/IJMS19103050},

issn = {1422-0067},

year  = {2018},

date = {2018-01-01},

journal = {International Journal of Molecular Sciences 2018, Vol. 19, Page 3050},

volume = {19},

issue = {10},

pages = {3050},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Xanthomonas citri subsp. citri (Xcc) causes citrus canker, affecting sweet orange-producing areas around the world. The current chemical treatment available for this disease is based on cupric compounds. For this reason, the objective of this study was to design antibacterial agents. In order to do this, we analyzed the anti-Xcc activity of 36 alkyl dihydroxybenzoates and we found 14 active compounds. Among them, three esters with the lowest minimum inhibitory concentration values were selected; compounds 4 (52 μM), 16 (80 μM) and 28 (88 μM). Our study demonstrated that alkyl dihydroxybenzoates cause a delay in the exponential phase. The permeability capacity of alkyl dihydroxybenzoates in a quarter of MIC was compared to nisin (positive control). Compound 28 was the most effective (93.8), compared to compound 16 (41.3) and compound 4 (13.9) by percentage values. Finally, all three compounds showed inhibition of FtsZ GTPase activity, and promoted changes in protofilaments, leading to depolymerization, which prevents bacterial cell division. In conclusion, heptyl dihydroxybenzoates (compounds 4, 16 and 28) are promising anti-Xcc agents which may serve as an alternative for the control of citrus canker.},

keywords = {Antimicrobial, Citrus canker, membrane disruption, phenolic acids, plant disease},

pubstate = {published},

tppubtype = {article}

}

@article{Vieira2018,

title = {Terrestrial and marine Antarctic fungi extracts active against Xanthomonas citri subsp. citri},

author = {G. Vieira and J. Purić and L. G. Morão and J. A. Santos and F. J. Inforsato and L. D. Sette and H. Ferreira and D. C. Sass},

url = {https://onlinelibrary.wiley.com/doi/full/10.1111/lam.12890 https://onlinelibrary.wiley.com/doi/abs/10.1111/lam.12890 https://ami-journals.onlinelibrary.wiley.com/doi/10.1111/lam.12890},

doi = {10.1111/LAM.12890},

issn = {1472-765X},

year  = {2018},

date = {2018-01-01},

journal = {Letters in Applied Microbiology},

volume = {67},

issue = {1},

pages = {64-71},

publisher = {John Wiley & Sons, Ltd},

abstract = {This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctica and assess its potential antibacterial activity on Xanthomonas citri subsp. citri, the agent of citrus canker. Metabolites production was conducted in Malt 2% broth at 15°C for 20 days after which intracellular and extracellular extracts were obtained. The extracts were evaluated by cell viability assays through Resazurin Microtitre Assay. From 158 fungal extracts, 33 hampered bacterial growth in vitro. The average inhibition of the extracts obtained from terrestrial (soil) and marine (sediments) fungi was 94 and 97% respectively. These inhibition values were close to the average of 90% cell death for the positive control. MIC90 and MBC for the bioactive extracts were established. Isolates that produced active metabolites against the phytopathogen were identified using molecular taxonomy (ITS-rRNA sequencing) as: Pseudogymnoascus, Penicillium, Cadophora, Paraconiothyrium and Toxicocladosporium. Antarctic fungal strains isolated from terrestrial and marine sediments were able to produce secondary metabolites with antimicrobial activity against X. citri subsp. citri, highlighting the importance of these microbial genetic resources. These metabolites have potential to be used as alternatives for the control of this plant pathogen. Significance and Impact of the Study: This manuscript makes an impact on the study of micro-organisms from extreme habitats and their possible contribution in discovering new active molecules against pathogens of agricultural interest. Studies on the Antarctic continent and its communities have attracted the scientific community due to the long period of isolation and low levels of disturbance that surrounds the region. Knowing the potential of fungi in this region to produce active secondary metabolites, we aim to contribute to the discovery of compounds with antibacterial action in Xanthomonas citri subsp. citri, a plant pathogen present in several regions around the globe.},

keywords = {Antarctic fungi, antibacterial action, Citrus canker, Secondary metabolites, Xanthomonas},

pubstate = {published},

tppubtype = {article}

}

@article{Dalio2017,

title = {PAMPs, PRRs, effectors and R-genes associated with citrus–pathogen interactions},

author = {Ronaldo J. D. Dalio and Diogo M. Magalhaes and Carolina M. Rodrigues and Gabriella D. Arena and Tiago S. Oliveira and Reinaldo R. Souza-Neto and Simone C. Picchi and Paula M. M. Martins and Paulo J. C. Santos and Heros J. Maximo and Inaiara S. Pacheco and Alessandra A. De Souza and Marcos A. Machado},

url = {https://academic.oup.com/aob/article/119/5/749/2870523},

doi = {10.1093/AOB/MCW238},

issn = {0305-7364},

year  = {2017},

date = {2017-01-01},

journal = {Annals of Botany},

volume = {119},

issue = {5},

pages = {749-774},

publisher = {Oxford Academic},

abstract = {• Background Recent application of molecular-based technologies has considerably advanced our understanding of complex processes in plant-pathogen interactions and their key components such as PAMPs, PRRs, effectors and R-genes. To develop novel control strategies for disease prevention in citrus, it is essential to expand and consolidate our knowledge of the molecular interaction of citrus plants with their pathogens. • Scope This review provides an overview of our understanding of citrus plant immunity, focusing on the molecular mechanisms involved in the interactions with viruses, bacteria, fungi, oomycetes and vectors related to the following diseases: tristeza, psorosis, citrus variegated chlorosis, citrus canker, huanglongbing, brown spot, post-bloom, anthracnose, gummosis and citrus root rot.},

keywords = {Anthracnose, Brown spot, Citrus canker, Citrus immunity, Citrus psorosis, Citrus root rot, Citrus variegated chlorosis (CVC), Gummosis, Huanglongbing (HLB), Post-bloom, Tristeza of citrus},

pubstate = {published},

tppubtype = {article}

}

@article{Lacerda2017,

title = {Protein depletion using the arabinose promoter in Xanthomonas citri subsp. citri},

author = {Lilian A. Lacerda and Lucia B. Cavalca and Paula M. M. Martins and José S. Govone and Maurício Bacci and Henrique Ferreira},

doi = {10.1016/J.PLASMID.2017.03.005},

issn = {0147-619X},

year  = {2017},

date = {2017-01-01},

journal = {Plasmid},

volume = {90},

pages = {44-52},

publisher = {Academic Press},

abstract = {Xanthomonas citri subsp. citri (X. citri) is a plant pathogen and the etiological agent of citrus canker, a severe disease that affects all the commercially important citrus varieties, and has worldwide distribution. Citrus canker cannot be healed, and the best method known to control the spread of X. citri in the orchards is the eradication of symptomatic and asymptomatic plants in the field. However, in the state of São Paulo, Brazil, the main orange producing area in the world, control is evolving to an integrated management system (IMS) in which growers have to use less susceptible plants, windshields to prevent bacterial spread out and sprays of cupric bactericidal formulations. Our group has recently proposed alternative methods to control citrus canker, which are based on the use of chemical compounds able to disrupt vital cellular processes of X. citri. An important step in this approach is the genetic and biochemical characterization of genes/proteins that are the possible targets to be perturbed, a task not always simple when the gene/protein under investigation is essential for the organism. Here, we describe vectors carrying the arabinose promoter that enable controllable protein expression in X. citri. These vectors were used as complementation tools for the clean deletion of parB in X. citri, a widespread and conserved gene involved in the essential process of bacterial chromosome segregation. Overexpression or depletion of ParB led to increased cell size, which is probably a resultant of delayed chromosome segregation with subsequent retard of cell division. However, ParB is not essential in X. citri, and in its absence the bacterium was fully competent to colonize the host citrus and cause disease. The arabinose expression vectors described here are valuable tools for protein expression, and especially, to assist in the deletion of essential genes in X. citri.},

keywords = {Bacterial gene knockout, Chromosome segregation, Citrus canker},

pubstate = {published},

tppubtype = {article}

}

@article{Lorenzoni2017,

title = {Xanthomonas citri MinC oscillates from pole to pole to ensure proper cell division and shape},

author = {André S. G. Lorenzoni and Giordanni C. Dantas and Tessa Bergsma and Henrique Ferreira and Dirk Jan Scheffers},

doi = {10.3389/FMICB.2017.01352/BIBTEX},

issn = {1664302X},

year  = {2017},

date = {2017-01-01},

journal = {Frontiers in Microbiology},

volume = {8},

issue = {JUL},

pages = {1352},

publisher = {Frontiers Media S.A.},

abstract = {Xanthomonas citri (Xac) is the causal agent of citrus canker, a disease that affects citrus crops and causes economic impact worldwide. To further characterize cell division in this plant pathogen, we investigated the role of the protein MinC in cell division, chromosome segregation, and peptidoglycan incorporation by deleting the gene minC using allele exchange. Xac with minC deleted exhibited the classic Δmin phenotype observed in other bacteria deleted for min components: minicells and short filamentation. In addition we noticed the formation of branches, which is similar to what was previously described for Escherichia coli deleted for either min or for several low molecular weight penicillin-binding proteins (PBPs). The branching phenotype was medium dependent and probably linked to gluconeogenic growth. We complemented the minC gene by integrating gfp-minC into the amy locus. Xac complemented strains displayed a wild-type phenotype. In addition, GFP-MinC oscillated from pole to pole, similar to MinCD oscillations observed in E. coli and more recently in Synechococcus elongatus. Further investigation of the branching phenotype revealed that in branching cells nucleoid organization, divisome formation and peptidoglycan incorporation were disrupted.},

keywords = {Citrus canker, FtsZ, MinC, ParB, Peptidoglycan, Xanthomonas citri, ZapA},

pubstate = {published},

tppubtype = {article}

}