Publications

@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{Pierry2020,

title = {Genetic Diversity of Xylella fastidiosa Plasmids Assessed by Comparative Genomics},

author = {Paulo Marques Pierry and Guillermo Uceda-Campos and Oseias Rodrigues Feitosa-Junior and Joaquim Martins-Junior and Wesley Oliveira Santana and Helvécio Della Coletta-Filho and Paulo Adriano Zaini and Aline Maria Silva},

url = {https://link.springer.com/article/10.1007/s40858-020-00359-4},

doi = {10.1007/S40858-020-00359-4/METRICS},

issn = {19832052},

year  = {2020},

date = {2020-01-01},

journal = {Tropical Plant Pathology},

volume = {45},

issue = {3},

pages = {342-360},

publisher = {Springer},

abstract = {Plasmids are a major source of horizontal gene transfer among bacteria contributing to their evolution and ecology. The known collection of plasmids carried by the plant pathogen Xylella fastidiosa increases as new strains from different origins and hosts are sampled and sequenced. Here we performed an extensive comparison of 61 publicly available sequences annotated as plasmids belonging to 38 X. fastidiosa strains isolated from different plant species and distinct geographical locations. Twenty-six strains exhibited at least one plasmid and up to four plasmids were found in a single strain. Plasmids sizes varied widely from 1.3 kbp to 64.3 kbp, ranging from 1 to 70 protein-coding sequences (CDS) encompassing 324 orthologs. Based on the presence of specific mobility proteins such as relaxases and type 4 secretion system-related genes, respectively 40 and 8 of the X. fastidiosa plasmids were classified as conjugative and mobilizable, while 13 were classified as non-mobilizable. X. fastidiosa plasmids did not carry known antibiotic resistance or virulence genes, and their stability seems to take advantage of toxin/antitoxin systems. The comparative analyses described here revealed similarity among plasmids of X. fastidiosa from different subspecies, geographical regions, and hosts, as well as with sequences found in plasmids from other bacterial species. Altogether, our results provide an in silico analysis of X. fastidiosa plasmid content and their main features, with applications in future studies of epidemiology, ecology, and evolution of this phytopathogen.},

keywords = {Conjugative plasmid, Horizontal gene transfer, Phytopathogen, Plasmid classification, Relaxase, Type IV coupling protein},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Activity of Antarctic fungi extracts against phytopathogenic bacteria},

author = {J. Purić and G. Vieira and L. B. Cavalca and L. D. Sette and H. Ferreira and M. L. C. Vieira and D. C. Sass},

url = {https://onlinelibrary.wiley.com/doi/full/10.1111/lam.12875 https://onlinelibrary.wiley.com/doi/abs/10.1111/lam.12875 https://ami-journals.onlinelibrary.wiley.com/doi/10.1111/lam.12875},

doi = {10.1111/LAM.12875},

issn = {1472-765X},

year  = {2018},

date = {2018-01-01},

journal = {Letters in Applied Microbiology},

volume = {66},

issue = {6},

pages = {530-536},

publisher = {John Wiley & Sons, Ltd},

abstract = {This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctic ecosystems and to assess its potential antibacterial activity on Xanthomonas euvesicatoria and Xanthomonas axonopodis pv. passiflorae (phytopathogenic bacteria causing diseases in pepper and tomato and passionfruit, respectively). Among the 66 crude intracellular and extracellular extracts obtained from fungi recovered from soil and 79 obtained from marine sediment samples, 25 showed the ability to prevent the growth of X. euvesicatoria in vitro and 28 showed the ability to prevent the growth of X. axonopodis pv. passiflorae in vitro. Intracellular and extracellular extracts from soil fungi inhibited around 97% of X. euvesicatoria and 98% of X. axonopodis pv. passiflorae at 2·1 mg ml−1. The average inhibition rates against X. euvesicatoria and X. axonopodis pv. passiflorae for intracellular and extracellular extracts from marine sediments fungi were around 96 and 97%, respectively, at 3·0 mg ml−1. Extracts containing secondary metabolites with antimicrobial activity against X. euvesicatoria and X. axonopodis pv. passiflorae were obtained, containing possible substitutes for the products currently used to control these phytopathogens. Significance and Impact of the Study: Micro-organisms from extreme ecosystems, such as the Antarctic ecosystem, need to survive in harsh conditions with low temperatures, low nutrients and high UV radiation. Micro-organisms adapt to these conditions evolving diverse biochemical and physiological adaptations essential for survival. All this makes these micro-organisms a rich source of novel natural products based on unique chemical scaffolds. Discovering novel bioactive compounds is essential because of the rise in antibiotic-resistant micro-organisms and the emergence of new infections. Fungi from Antarctic environments have been proven to produce bioactive secondary metabolites against various micro-organisms, but few studies have shown activity against Xanthomonas phytopathogens.},

keywords = {Antibacterial, passionfruit, Phytopathogen, Tomato, Xanthomonas},

pubstate = {published},

tppubtype = {article}

}

@article{Martins2018,

title = {Persistence in phytopathogenic bacteria: Do we know enough?},

author = {Paula M. M. Martins and Marcus V. Merfa and Marco A. Takita and Alessandra A. De Souza},

doi = {10.3389/FMICB.2018.01099/BIBTEX},

issn = {1664302X},

year  = {2018},

date = {2018-01-01},

journal = {Frontiers in Microbiology},

volume = {9},

issue = {MAY},

pages = {1099},

publisher = {Frontiers Media S.A.},

abstract = {Phytopathogenic bacteria affect a wide range of crops worldwide and have a negative impact in agriculture due to their associated economic losses and environmental impacts. Together with other biotic and abiotic stress factors, they pose a threat to global food production. Therefore, understanding bacterial survival strategies is an essential step toward the development of new strategies to control plant diseases. One mechanism used by bacteria to survive under stress conditions is the formation of persister cells. Persisters are a small fraction of phenotypic variants within an isogenic population that exhibits multidrug tolerance without undergoing genetic changes. They are dormant cells that survive treatment with antimicrobials by inactivating the metabolic functions that are disrupted by these compounds. They are thus responsible for the recalcitrance of many human diseases, and in the same way, they are thought to contribute to the survival of bacterial phytopathogens under a range of stresses they face in the environment. It is believed that persister cells of bacterial phytopathogens may lead to the reoccurrence of disease by recovering growth and recolonizing the host plant after the end of stress. However, compared to human pathogens, little is known about persister cells in phytopathogens, especially about their genetic regulation. In this review, we describe the overall knowledge on persister cells and their regulation in bacterial phytopathogens, focusing on their ability to survive stress conditions, to recover from dormancy and to maintain virulence.},

keywords = {Crop diseases, Oxidative stress, Persisters, Phytopathogen, Toxin-antitoxin systems, VBNC},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Activity of Antarctic fungi extracts against phytopathogenic bacteria},

author = {J. Purić and G. Vieira and L. B. Cavalca and L. D. Sette and H. Ferreira and M. L. C. Vieira and D. C. Sass},

url = {https://onlinelibrary.wiley.com/doi/full/10.1111/lam.12875 https://onlinelibrary.wiley.com/doi/abs/10.1111/lam.12875 https://ami-journals.onlinelibrary.wiley.com/doi/10.1111/lam.12875},

doi = {10.1111/LAM.12875},

issn = {1472-765X},

year  = {2018},

date = {2018-01-01},

journal = {Letters in Applied Microbiology},

volume = {66},

issue = {6},

pages = {530-536},

publisher = {John Wiley & Sons, Ltd},

abstract = {This study aims to obtain secondary metabolites extracts from filamentous fungi isolated from soil and marine sediments from Antarctic ecosystems and to assess its potential antibacterial activity on Xanthomonas euvesicatoria and Xanthomonas axonopodis pv. passiflorae (phytopathogenic bacteria causing diseases in pepper and tomato and passionfruit, respectively). Among the 66 crude intracellular and extracellular extracts obtained from fungi recovered from soil and 79 obtained from marine sediment samples, 25 showed the ability to prevent the growth of X. euvesicatoria in vitro and 28 showed the ability to prevent the growth of X. axonopodis pv. passiflorae in vitro. Intracellular and extracellular extracts from soil fungi inhibited around 97% of X. euvesicatoria and 98% of X. axonopodis pv. passiflorae at 2·1 mg ml−1. The average inhibition rates against X. euvesicatoria and X. axonopodis pv. passiflorae for intracellular and extracellular extracts from marine sediments fungi were around 96 and 97%, respectively, at 3·0 mg ml−1. Extracts containing secondary metabolites with antimicrobial activity against X. euvesicatoria and X. axonopodis pv. passiflorae were obtained, containing possible substitutes for the products currently used to control these phytopathogens. Significance and Impact of the Study: Micro-organisms from extreme ecosystems, such as the Antarctic ecosystem, need to survive in harsh conditions with low temperatures, low nutrients and high UV radiation. Micro-organisms adapt to these conditions evolving diverse biochemical and physiological adaptations essential for survival. All this makes these micro-organisms a rich source of novel natural products based on unique chemical scaffolds. Discovering novel bioactive compounds is essential because of the rise in antibiotic-resistant micro-organisms and the emergence of new infections. Fungi from Antarctic environments have been proven to produce bioactive secondary metabolites against various micro-organisms, but few studies have shown activity against Xanthomonas phytopathogens.},

keywords = {Antibacterial, passionfruit, Phytopathogen, Tomato, Xanthomonas},

pubstate = {published},

tppubtype = {article}

}