Cordeirópolis, Brazil
Cordeirópolis, Brazil

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Roose M.L.,University of California at Riverside | Gmitter F.G.,University of Florida | Lee R.,U.S. Department of Agriculture | Hummer K.,U.S. Department of Agriculture | And 8 more authors.
Acta Horticulturae | Year: 2015

Citrus is an economically important world tree fruit crop with production in more than 146 countries. The center of origin for citrus is considered to be Southeastern Asia including southern China, northeastern India, and Malaysia, with secondary centers in surrounding areas. Novel and commercially significant scion and rootstock cultivars originating by natural mutation or directed hybridization were introduced during the past century. Significant genetic resource collections exist in many countries. A global citrus germplasm network was developed in 1997. Now that the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGR) has recognized Citrus as an Annex 1 crop, a global conservation strategy needs to be established. The objective of this workshop was to plan the development of this strategy. More than 60 delegates attended with representation from Argentina, Australia, Bhutan, Brazil, China, Columbia, France, Iran, Israel, Italy, Japan, Mexico, Morocco, Portugal, Spain, Turkey, UAE, US, and Vietnam. Nine oral presentations were given describing multiple aspects of genebank operations, technologies and gaps in Brazil, China, France, Australia, Spain, and the US. A draft genebank survey questionnaire was presented to the group and comments and suggested changes for improvement were received. Citrus curators and genebank managers throughout the world will be surveyed for the status and health of their collections. The surveys will be received and compiled by collaborators at the University of California, Riverside, and at the USDA ARS Riverside. This information will be compiled and reported. The strategy will include background and history of the development of Citrus as a cultivated crop, conservation protocols, vulnerabilities, and recommendations for safeguarding Citrus germplasm. This strategy will be implemented through the Global Crop Diversity Trust with collaboration from the International Society for Horticultural Science and the international Citrus research community.


Santos C.A.,University of Campinas | Toledo M.A.S.,University of Campinas | Trivella D.B.B.,University of Campinas | Beloti L.L.,University of Campinas | And 8 more authors.
FEBS Journal | Year: 2012

Xylella fastidiosa is a Gram-negative bacterium that grows as a biofilm inside the xylem vessels of susceptible plants and causes several economically relevant crop diseases. In the present study, we report the functional and low-resolution structural characterization of the X. fastidiosa disulfide isomerase DsbC (XfDsbC). DsbC is part of the disulfide bond reduction/ isomerization pathway in the bacterial periplasm and plays an important role in oxidative protein folding. In the present study, we demonstrate the presence of XfDsbC during different stages of X. fastidiosa biofilm development. XfDsbC was not detected during X. fastidiosa planktonic growth; however, after administering a sublethal copper shock, we observed an overexpression of XfDsbC that also occurred during planktonic growth. These results suggest that X. fastidiosa can use XfDsbC in vivo under oxidative stress conditions similar to those induced by copper. In addition, using dynamic light scattering and small-angle X-ray scattering, we observed that the oligomeric state of XfDsbC in vitro may be dependent on the redox environment. Under reducing conditions, XfDsbC is present as a dimer, whereas a putative tetrameric form was observed under nonreducing conditions. Taken together, our findings demonstrate the overexpression of XfDsbC during biofilm formation and provide the first structural model of a bacterial disulfide isomerase in solution. © 2012 The Authors Journal compilation © 2012 FEBS.


Cappelletti P.A.,University of Sao Paulo | dos Santos R.F.,University of Sao Paulo | do Amaral A.M.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária | do Amaral A.M.,Centro APTA Citros Sylvio Moreira IAC | And 4 more authors.
PLoS ONE | Year: 2011

Bacterial type III secretion systems deliver protein virulence factors to host cells. Here we characterize the interaction between HrpB2, a small protein secreted by the Xanthomonas citri subsp. citri type III secretion system, and the cytosolic domain of the inner membrane protein HrcU, a paralog of the flagellar protein FlhB. We show that a recombinant fragment corresponding to the C-terminal cytosolic domain of HrcU produced in E. coli suffers cleavage within a conserved Asn264-Pro265-Thr266-His267 (NPTH) sequence. A recombinant HrcU cytosolic domain with N264A, P265A, T266A mutations at the cleavage site (HrcUAAAH) was not cleaved and interacted with HrpB2. Furthermore, a polypeptide corresponding to the sequence following the NPTH cleavage site also interacted with HrpB2 indicating that the site for interaction is located after the NPTH site. Non-polar deletion mutants of the hrcU and hrpB2 genes resulted in a total loss of pathogenicity in susceptible citrus plants and disease symptoms could be recovered by expression of HrpB2 and HrcU from extrachromossomal plasmids. Complementation of the ΔhrcU mutant with HrcUAAAH produced canker lesions similar to those observed when complemented with wild-type HrcU. HrpB2 secretion however, was significantly reduced in the ΔhrcU mutant complemented with HrcUAAAH, suggesting that an intact and cleavable NPTH site in HrcU is necessary for total functionally of T3SS in X. citri subsp. citri. Complementation of the ΔhrpB2 X. citri subsp. citri strain with a series of hrpB2 gene mutants revealed that the highly conserved HrpB2 C-terminus is essential for T3SS-dependent development of citrus canker symptoms in planta. © 2011 Cappelletti et al.


Coletta-Filho H.D.,Centro APTA Citros Sylvio Moreira IAC | Goncalves F.P.,University of Sao Paulo | Amorim L.,University of Sao Paulo | de Souza A.A.,Centro APTA Citros Sylvio Moreira IAC | Machado M.A.,Centro APTA Citros Sylvio Moreira IAC
Journal of Plant Pathology | Year: 2013

Contrary to the well-documented incidence and severity of Citrus variegated chlorosis (CVC) throughout the sweet orange groves of São Paulo state (Brazil), the incidence and distribution of its causal agent, Xylella fastidiosa, is not well known. Sweet orange samples selected according to variety and age were collected from commercial groves in northern, central and southern regions of São Paulo state and analysed visually for the presence of symptoms and by PCR for the presence of X. fastidiosa. A decreasing gradient of both infected and symptomatic trees from northern to southern regions of the state was observed. However, there was a higher incidence of latent infection (symptomless trees) in the southern (32%) than in the northern and central regions (16%). The survey disclosed an increasing gradient of CVC and X. fastidiosa incidence according to the age of the trees. Infected trees younger than two years were observed only in the central region. CVC symptom expression is related to environmental conditions and the incidence of symptomatic trees does not correspond with that of trees infected by X. fastidiosa.


Nunes M.A.,Centro APTA Citros Sylvio Moreira IAC | de Oliveira C.A.L.,São Paulo State University | De Oliveira M.L.,São Paulo State University | Kitajima E.W.,ESALQ | And 3 more authors.
Plant Disease | Year: 2012

The equivalent of US$75 million is spent each year in Brazil to control Brevipalpus phoenicis, a mite vector of Citrus leprosis virus C (CiLVC). In this study, we investigated the possibility that hedgerows and windbreaks normally found in citrus orchards could host CiLV-C. Mites confined by an adhesive barrier were reared on sweet orange fruit with leprosis symptoms then were transferred to leaves of Hibiscus rosa-sinensis, Malvaviscus arboreus, Grevilea robusta, Bixaorellana, and Citrus sinensis. Ninety days post infestation, the descendant mites were transferred to Pera sweet orange plants to verify the transmissibility of the virus back to citrus. Nonviruliferous mites which had no feeding access to diseased tissue were used as controls. Local chlorotic or necrotic spots and ringspots, symptoms of leprosies disease, appeared in most plants tested. Results generated by reversetranscription polymerase chain reaction with primers specific for CiLVC and by electron microscope analyses confirmed the susceptibility of these plants to CiLV-C. © 2012 The American Phytopathological Society.


Muranaka L.S.,Centro APTA Citros Sylvio Moreira IAC | Muranaka L.S.,University of Campinas | Takita M.A.,Centro APTA Citros Sylvio Moreira IAC | Olivato J.C.,Centro APTA Citros Sylvio Moreira IAC | And 2 more authors.
Journal of Bacteriology | Year: 2012

Investigations of biofilm resistance response rarely focus on plant-pathogenic bacteria. Since Xylella fastidiosa is a multihost plant-pathogenic bacterium that forms biofilm in the xylem, the behavior of its biofilm in response to antimicrobial compounds needs to be better investigated. We analyzed here the transcriptional profile of X. fastidiosa subsp. pauca in response to inhibitory and subinhibitory concentrations of copper and tetracycline. Copper-based products are routinely used to control citrus diseases in the field, while antibiotics are more widely used for bacterial control in mammals. The use of antimicrobial compounds triggers specific responses to each compound, such as biofilm formation and phage activity for copper. Common changes in expression responses comprise the repression of genes associated with metabolic functions and movement and the induction of toxin-antitoxin systems, which have been associated with the formation of persister cells.Ourresults also show that these cells were found in the population at a ca. 0.05% density under inhibitory conditions for bothantimicrobial compounds and that pretreatment with subinhibitory concentration of copper increases this number. No previousreport has detected the presence of these cells in X. fastidiosa population, suggesting that this could lead to a multidrugtolerance response in the biofilm under a stressed environment. This is a mechanism that has recently become the focusof studies on resistance of humanpathogenic bacteria to antibiotics and, based on our data, it seems to be more broadlyapplicable. © 2012, American Society for Microbiology.


Sanchez-Velazquez E.J.,Colegio de Mexico | Santillan-Galicia M.T.,Colegio de Mexico | Novelli V.M.,Centro APTA Citros Sylvio Moreira IAC | Nunes M.A.,Centro APTA Citros Sylvio Moreira IAC | And 4 more authors.
PLoS ONE | Year: 2015

Brevipalpus phoenicis s.l. is an economically important vector of the Citrus leprosis virus-C (CiLV-C), one of the most severe diseases attacking citrus orchards worldwide. Effective control strategies for this mite should be designed based on basic information including its population structure, and particularly the factors that influence its dynamics. We sampled sweet orange orchards extensively in eight locations in Brazil and 12 in Mexico. Population genetic structure and genetic variation between both countries, among locations and among sampling sites within locations were evaluated by analysing nucleotide sequence data from fragments of the mitochondrial cytochrome oxidase subunit I (COI). In both countries, B. yothersi was the most common species and was found in almost all locations. Individuals from B. papayensis were found in two locations in Brazil. Brevipalpus yothersi populations collected in Brazil were more genetically diverse (14 haplotypes) than Mexican populations (four haplotypes). Although geographical origin had a low but significant effect (ca. 25%) on the population structure, the greatest effect was from the within location comparison (37.02 %). Potential factors driving our results were discussed. © 2015 Sánchez-Velázquez et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Mendes J.S.,University of Campinas | Da Santiago A.S.,University of Campinas | Toledo M.A.S.,University of Campinas | Rosselli-Murai L.K.,University of Campinas | And 9 more authors.
PLoS ONE | Year: 2015

Xylella fastidiosa strain 9a5c is a gram-negative phytopathogen that is the causal agent of citrus variegated chlorosis (CVC), a disease that is responsible for economic losses in Brazilian agriculture. The most well-known mechanism of pathogenicity for this bacterial pathogen is xylem vessel occlusion, which results from bacterial movement and the formation of biofilms. The molecular mechanisms underlying the virulence caused by biofilm formation are unknown. Here, we provide evidence showing that virulence-associated protein D in X. fastidiosa (Xf-VapD) is a thermostable protein with ribonuclease activity. Moreover, protein expression analyses in two X. fastidiosa strains, including virulent (Xf9a5c) and nonpathogenic (XfJ1a12) strains, showed that Xf-VapD was expressed during all phases of development in both strains and that increased expression was observed in Xf9a5c during biofilm growth. This study is an important step toward characterizing and improving our understanding of the biological significance of Xf-VapD and its potential functions in the CVC pathosystem. © 2015 Mendes et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


PubMed | Centro APTA Citros Sylvio Moreira IAC and University of Campinas
Type: Journal Article | Journal: PloS one | Year: 2015

Xylella fastidiosa strain 9a5c is a gram-negative phytopathogen that is the causal agent of citrus variegated chlorosis (CVC), a disease that is responsible for economic losses in Brazilian agriculture. The most well-known mechanism of pathogenicity for this bacterial pathogen is xylem vessel occlusion, which results from bacterial movement and the formation of biofilms. The molecular mechanisms underlying the virulence caused by biofilm formation are unknown. Here, we provide evidence showing that virulence-associated protein D in X. fastidiosa (Xf-VapD) is a thermostable protein with ribonuclease activity. Moreover, protein expression analyses in two X. fastidiosa strains, including virulent (Xf9a5c) and nonpathogenic (XfJ1a12) strains, showed that Xf-VapD was expressed during all phases of development in both strains and that increased expression was observed in Xf9a5c during biofilm growth. This study is an important step toward characterizing and improving our understanding of the biological significance of Xf-VapD and its potential functions in the CVC pathosystem.


PubMed | Centro APTA Citros Sylvio Moreira IAC
Type: Journal Article | Journal: Journal of bacteriology | Year: 2012

Investigations of biofilm resistance response rarely focus on plant-pathogenic bacteria. Since Xylella fastidiosa is a multihost plant-pathogenic bacterium that forms biofilm in the xylem, the behavior of its biofilm in response to antimicrobial compounds needs to be better investigated. We analyzed here the transcriptional profile of X. fastidiosa subsp. pauca in response to inhibitory and subinhibitory concentrations of copper and tetracycline. Copper-based products are routinely used to control citrus diseases in the field, while antibiotics are more widely used for bacterial control in mammals. The use of antimicrobial compounds triggers specific responses to each compound, such as biofilm formation and phage activity for copper. Common changes in expression responses comprise the repression of genes associated with metabolic functions and movement and the induction of toxin-antitoxin systems, which have been associated with the formation of persister cells. Our results also show that these cells were found in the population at a ca. 0.05% density under inhibitory conditions for both antimicrobial compounds and that pretreatment with subinhibitory concentration of copper increases this number. No previous report has detected the presence of these cells in X. fastidiosa population, suggesting that this could lead to a multidrug tolerance response in the biofilm under a stressed environment. This is a mechanism that has recently become the focus of studies on resistance of human-pathogenic bacteria to antibiotics and, based on our data, it seems to be more broadly applicable.

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