682 results on '"P Trouillas"'
Search Results
2. Pathogenicity, phylogenomic, and comparative genomic study of Pseudomonas syringae sensu lato affecting sweet cherry in California.
- Author
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Maguvu, Tawanda, Frias, Rosa, Hernandez-Rosas, Alejandro, Shipley, Erin, Dardani, Greta, Nouri, Mohamed, Yaghmour, Mohammad, and Trouillas, Florent
- Subjects
Prunus avium ,Pseudomonas syringae ,antibiotic resistance ,bacterial blast ,bacterial canker ,blossom blast ,comparative genomics ,genome mining ,genomics ,pathogenicity ,phylogenetic analysis ,sweet cherry ,Plant Diseases ,Pseudomonas syringae ,California ,Phylogeny ,Prunus avium ,Genome ,Bacterial ,Virulence ,Genomics ,Bacterial Proteins - Abstract
UNLABELLED: To gain insights into the diversity of Pseudomonas syringae sensu lato affecting sweet cherry in California, we sequenced and analyzed the phylogenomic and genomic architecture of 86 fluorescent pseudomonads isolated from symptomatic and asymptomatic cherry tissues. Fifty-eight isolates were phylogenetically placed within the P. syringae species complex and taxonomically classified into five genomospecies: P. syringae pv. syringae, P. syringae, Pseudomonas cerasi, Pseudomonas viridiflava, and A. We annotated components of the type III secretion system and phytotoxin-encoding genes and correlated the data with pathogenicity phenotypes. Intact probable regulatory protein HrpR was annotated in the genomic sequences of all isolates of P. syringae pv. syringae, P. syringae, P. cerasi, and A. Isolates of P. viridiflava had atypical probable regulatory protein HrpR. Syringomycin and syringopeptin-encoding genes were annotated in isolates of all genomospecies except for A and P. viridiflava. All isolates of P. syringae pv. syringae caused cankers, leaf spots, and fruit lesions in the field. In contrast, all isolates of P. syringae and P. cerasi and some isolates of P. viridiflava caused only cankers. Isolates of genomospecies A could not cause any symptoms suggesting phytotoxins are essential for pathogenicity. On detached immature cherry fruit pathogenicity assays, isolates of all five genomospecies produced symptoms (black-dark brown lesions). However, symptoms of isolates of genomospecies A were significantly (P < 0.01) less severe than those of other genomospecies. We also mined for genes conferring resistance to copper and kasugamycin and correlated these data with in vitro antibiotic sensitivity tests. IMPORTANCE: Comprehensive identification of phytopathogens and an in-depth understanding of their genomic architecture, particularly virulence determinants and antibiotic-resistant genes, are critical for several practical reasons. These include disease diagnosis, improved knowledge of disease epidemiology, pathogen diversity, and determination of the best possible management strategies. In this study, we provide the first report of the presence and pathogenicity of genomospecies Pseudomonas cerasi and Pseudomonas viridiflava in California sweet cherry. More importantly, we report a relatively high level of resistance to copper among the population of Pseudomonas syringae pv. syringae (47.5%). This implies copper cannot be effectively used to control bacterial blast and bacterial canker of sweet cherries. On the other hand, no isolates were resistant to kasugamycin, an indication that kasugamycin could be effectively used for the control of bacterial blast and bacterial canker. Our findings are important to improve the management of bacterial blast and bacterial canker of sweet cherries in California.
- Published
- 2024
3. Phylogenomic analyses and comparative genomics of Pseudomonas syringae associated with almond (Prunus dulcis) in California.
- Author
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Maguvu, Tawanda, Frias, Rosa, Hernandez-Rosas, Alejandro, Holtz, Brent, Niederholzer, Franz, Duncan, Roger, Yaghmour, Mohammad, Culumber, Catherine, Gordon, Phoebe, Vieira, Flavia, Rolshausen, Philippe, Adaskaveg, James, Burbank, Lindsey, Lindow, Steven, and Trouillas, Florent
- Subjects
Pseudomonas syringae ,Phylogeny ,Prunus dulcis ,Copper ,Ice ,Genomics ,Pseudomonas - Abstract
We sequenced and comprehensively analysed the genomic architecture of 98 fluorescent pseudomonads isolated from different symptomatic and asymptomatic tissues of almond and a few other Prunus spp. Phylogenomic analyses, genome mining, field pathogenicity tests, and in vitro ice nucleation and antibiotic sensitivity tests were integrated to improve knowledge of the biology and management of bacterial blast and bacterial canker of almond. We identified Pseudomonas syringae pv. syringae, P. cerasi, and P. viridiflava as almond canker pathogens. P. syringae pv. syringae caused both canker and foliar (blast) symptoms. In contrast, P. cerasi and P. viridiflava only caused cankers, and P. viridiflava appeared to be a weak pathogen of almond. Isolates belonging to P. syringae pv. syringae were the most frequently isolated among the pathogenic species/pathovars, composing 75% of all pathogenic isolates. P. cerasi and P. viridiflava isolates composed 8.3 and 16.7% of the pathogenic isolates, respectively. Laboratory leaf infiltration bioassays produced results distinct from experiments in the field with both P. cerasi and P. syringae pv. syringae, causing significant necrosis and browning of detached leaves, whereas P. viridiflava conferred moderate effects. Genome mining revealed the absence of key epiphytic fitness-related genes in P. cerasi and P. viridiflava genomic sequences, which could explain the contrasting field and laboratory bioassay results. P. syringae pv. syringae and P. cerasi isolates harboured the ice nucleation protein, which correlated with the ice nucleation phenotype. Results of sensitivity tests to copper and kasugamycin showed a strong linkage to putative resistance genes. Isolates harbouring the ctpV gene showed resistance to copper up to 600 μg/ml. In contrast, isolates without the ctpV gene could not grow on nutrient agar amended with 200 μg/ml copper, suggesting ctpV can be used to phenotype copper resistance. All isolates were sensitive to kasugamycin at the label-recommended rate of 100μg/ml.
- Published
- 2024
4. Whole genome sequencing and analysis of multiple isolates of Ceratocystis destructans, the causal agent of Ceratocystis canker of almond in California.
- Author
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Maguvu, Tawanda, Travadon, Renaud, Cantu, Dario, and Trouillas, Florent
- Subjects
Ceratocystis ,Prunus dulcis ,Plant Breeding ,California ,Geraniaceae ,Whole Genome Sequencing - Abstract
Ceratocystis canker caused by Ceratocystis destructans is a severe disease of almond, reducing the longevity and productivity of infected trees. Once the disease has established in an individual tree, there is no cure, and management efforts are often limited to removing the infected area of cankers. In this study, we present the genome assemblies of five C. destructans isolates isolated from symptomatic almond trees. The genomes were assembled into a genome size of 27.2 ± 0.9 Mbp with an average of 6924 ± 135 protein-coding genes and an average GC content of 48.8 ± 0.02%. We concentrated our efforts on identifying putative virulence factors of canker pathogens. Analysis of the secreted carbohydrate-active enzymes showed that the genomes harbored 83.4 ± 1.8 secreted CAZymes. The secreted CAZymes covered all the known categories of CAZymes. AntiSMASH revealed that the genomes had at least 7 biosynthetic gene clusters, with one of the non-ribosomal peptide synthases encoding dimethylcoprogen, a conserved virulence determinant of plant pathogenic ascomycetes. From the predicted proteome, we also annotated cytochrome P450 monooxygenases, and transporters, these are well-established virulence determinants of canker pathogens. Moreover, we managed to identify 57.4 ± 2.1 putative effector proteins. Gene Ontology (GO) annotation was applied to compare gene content with two closely related species C. fimbriata, and C. albifundus. This study provides the first genome assemblies for C. destructans, expanding genomic resources for an important almond canker pathogen. The acquired knowledge provides a foundation for further advanced studies, such as molecular interactions with the host, which is critical for breeding for resistance.
- Published
- 2023
5. Pathogenicity, phylogenomic, and comparative genomic study of Pseudomonas syringae sensu lato affecting sweet cherry in California
- Author
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Tawanda E. Maguvu, Rosa J. Frias, Alejandro I. Hernandez-Rosas, Erin Shipley, Greta Dardani, Mohamed T. Nouri, Mohammad A. Yaghmour, and Florent P. Trouillas
- Subjects
Pseudomonas syringae ,Prunus avium ,sweet cherry ,pathogenicity ,antibiotic resistance ,genomics ,Microbiology ,QR1-502 - Abstract
ABSTRACT To gain insights into the diversity of Pseudomonas syringae sensu lato affecting sweet cherry in California, we sequenced and analyzed the phylogenomic and genomic architecture of 86 fluorescent pseudomonads isolated from symptomatic and asymptomatic cherry tissues. Fifty-eight isolates were phylogenetically placed within the P. syringae species complex and taxonomically classified into five genomospecies: P. syringae pv. syringae, P. syringae, Pseudomonas cerasi, Pseudomonas viridiflava, and A. We annotated components of the type III secretion system and phytotoxin-encoding genes and correlated the data with pathogenicity phenotypes. Intact probable regulatory protein HrpR was annotated in the genomic sequences of all isolates of P. syringae pv. syringae, P. syringae, P. cerasi, and A. Isolates of P. viridiflava had atypical probable regulatory protein HrpR. Syringomycin and syringopeptin-encoding genes were annotated in isolates of all genomospecies except for A and P. viridiflava. All isolates of P. syringae pv. syringae caused cankers, leaf spots, and fruit lesions in the field. In contrast, all isolates of P. syringae and P. cerasi and some isolates of P. viridiflava caused only cankers. Isolates of genomospecies A could not cause any symptoms suggesting phytotoxins are essential for pathogenicity. On detached immature cherry fruit pathogenicity assays, isolates of all five genomospecies produced symptoms (black–dark brown lesions). However, symptoms of isolates of genomospecies A were significantly (P < 0.01) less severe than those of other genomospecies. We also mined for genes conferring resistance to copper and kasugamycin and correlated these data with in vitro antibiotic sensitivity tests.IMPORTANCEComprehensive identification of phytopathogens and an in-depth understanding of their genomic architecture, particularly virulence determinants and antibiotic-resistant genes, are critical for several practical reasons. These include disease diagnosis, improved knowledge of disease epidemiology, pathogen diversity, and determination of the best possible management strategies. In this study, we provide the first report of the presence and pathogenicity of genomospecies Pseudomonas cerasi and Pseudomonas viridiflava in California sweet cherry. More importantly, we report a relatively high level of resistance to copper among the population of Pseudomonas syringae pv. syringae (47.5%). This implies copper cannot be effectively used to control bacterial blast and bacterial canker of sweet cherries. On the other hand, no isolates were resistant to kasugamycin, an indication that kasugamycin could be effectively used for the control of bacterial blast and bacterial canker. Our findings are important to improve the management of bacterial blast and bacterial canker of sweet cherries in California.
- Published
- 2024
- Full Text
- View/download PDF
6. Whole genome sequencing and analysis of multiple isolates of Ceratocystis destructans, the causal agent of Ceratocystis canker of almond in California
- Author
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Tawanda E. Maguvu, Renaud Travadon, Dario Cantu, and Florent P. Trouillas
- Subjects
Medicine ,Science - Abstract
Abstract Ceratocystis canker caused by Ceratocystis destructans is a severe disease of almond, reducing the longevity and productivity of infected trees. Once the disease has established in an individual tree, there is no cure, and management efforts are often limited to removing the infected area of cankers. In this study, we present the genome assemblies of five C. destructans isolates isolated from symptomatic almond trees. The genomes were assembled into a genome size of 27.2 ± 0.9 Mbp with an average of 6924 ± 135 protein-coding genes and an average GC content of 48.8 ± 0.02%. We concentrated our efforts on identifying putative virulence factors of canker pathogens. Analysis of the secreted carbohydrate-active enzymes showed that the genomes harbored 83.4 ± 1.8 secreted CAZymes. The secreted CAZymes covered all the known categories of CAZymes. AntiSMASH revealed that the genomes had at least 7 biosynthetic gene clusters, with one of the non-ribosomal peptide synthases encoding dimethylcoprogen, a conserved virulence determinant of plant pathogenic ascomycetes. From the predicted proteome, we also annotated cytochrome P450 monooxygenases, and transporters, these are well-established virulence determinants of canker pathogens. Moreover, we managed to identify 57.4 ± 2.1 putative effector proteins. Gene Ontology (GO) annotation was applied to compare gene content with two closely related species C. fimbriata, and C. albifundus. This study provides the first genome assemblies for C. destructans, expanding genomic resources for an important almond canker pathogen. The acquired knowledge provides a foundation for further advanced studies, such as molecular interactions with the host, which is critical for breeding for resistance.
- Published
- 2023
- Full Text
- View/download PDF
7. Phylogenomic analyses and comparative genomics of Pseudomonas syringae associated with almond (Prunus dulcis) in California.
- Author
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Tawanda E Maguvu, Rosa J Frias, Alejandro I Hernandez-Rosas, Brent A Holtz, Franz J A Niederholzer, Roger A Duncan, Mohammad A Yaghmour, Catherine M Culumber, Phoebe E Gordon, Flavia C F Vieira, Philippe E Rolshausen, James E Adaskaveg, Lindsey P Burbank, Steven E Lindow, and Florent P Trouillas
- Subjects
Medicine ,Science - Abstract
We sequenced and comprehensively analysed the genomic architecture of 98 fluorescent pseudomonads isolated from different symptomatic and asymptomatic tissues of almond and a few other Prunus spp. Phylogenomic analyses, genome mining, field pathogenicity tests, and in vitro ice nucleation and antibiotic sensitivity tests were integrated to improve knowledge of the biology and management of bacterial blast and bacterial canker of almond. We identified Pseudomonas syringae pv. syringae, P. cerasi, and P. viridiflava as almond canker pathogens. P. syringae pv. syringae caused both canker and foliar (blast) symptoms. In contrast, P. cerasi and P. viridiflava only caused cankers, and P. viridiflava appeared to be a weak pathogen of almond. Isolates belonging to P. syringae pv. syringae were the most frequently isolated among the pathogenic species/pathovars, composing 75% of all pathogenic isolates. P. cerasi and P. viridiflava isolates composed 8.3 and 16.7% of the pathogenic isolates, respectively. Laboratory leaf infiltration bioassays produced results distinct from experiments in the field with both P. cerasi and P. syringae pv. syringae, causing significant necrosis and browning of detached leaves, whereas P. viridiflava conferred moderate effects. Genome mining revealed the absence of key epiphytic fitness-related genes in P. cerasi and P. viridiflava genomic sequences, which could explain the contrasting field and laboratory bioassay results. P. syringae pv. syringae and P. cerasi isolates harboured the ice nucleation protein, which correlated with the ice nucleation phenotype. Results of sensitivity tests to copper and kasugamycin showed a strong linkage to putative resistance genes. Isolates harbouring the ctpV gene showed resistance to copper up to 600 μg/ml. In contrast, isolates without the ctpV gene could not grow on nutrient agar amended with 200 μg/ml copper, suggesting ctpV can be used to phenotype copper resistance. All isolates were sensitive to kasugamycin at the label-recommended rate of 100μg/ml.
- Published
- 2024
- Full Text
- View/download PDF
8. Combining (Non-) Linear Optical and Fluorescence Analysis of DiD to Enhance Lipid Phase Recognition
- Author
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Osella, Silvio, Di Meo, Florent, Murugan, N. Arul, Fabre, Gabin, Ameloot, Marcel, Trouillas, Patrick, and Knippenberg, Stefan
- Subjects
Condensed Matter - Soft Condensed Matter ,Physics - Biological Physics ,Physics - Chemical Physics - Abstract
The widespread interest in phase recognition of lipid membranes has led to the use of different optical techniques to enable differentiation of healthy and not fully functional cells. In this work, we show how the combination of different (non)linear optical methods such as One Photon Absorption (OPA), Two Photon Absorption (TPA) and Second Harmonic Generation (SHG) as well as the study of the fluorescence decay time leads to an enhanced screening of membrane phases using a fluorescent dioctadecyltetramethylindocarbocyanine (DiD) probe. In the current study we consider the pure liquid disordered phases of DOPC (room temperature) and DPPC (323 K), the solid gel phase of DPPC (298 K), and the liquid ordered phase of a 2:1 binary mixture of Sphingomyelin and Cholesterol. By means of extensive hybrid quantum mechanics molecular mechanics calculations and based upon the (non) linear absorption of the embedded probes, it is found that DiD can be used to identify the lipid bilayer phase. The joint TPA and SHG as well as fluorescence analyses qualifies DiD as versatile probe for phase recognition. In particular, the SHG data obtained by means of HyperRayleigh Scattering and by Electric Field Induced Second Harmonic Generation reveal differences in polarization of the probe in the different environments. The TPA results finally confirm the particular location of the probe in between the polar head group region of the 2:1 SM:Chol mixture in the liquid ordered phase., Comment: 33 pages, 4 figures
- Published
- 2019
- Full Text
- View/download PDF
9. Atomistic picture of fluorescent probes with hydrocarbon tails in lipid bilayer membranes: an investigation of selective affinities and fluorescent anisotropies in different environmental phases
- Author
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Knippenberg, S., Fabre, G., Osella, S., Di Meo, F., Paloncýová, M., Ameloot, M., and Trouillas, P.
- Subjects
Condensed Matter - Soft Condensed Matter ,Physics - Biological Physics ,Physics - Chemical Physics - Abstract
By reverting to spectroscopy, changes in the biological environment of a fluorescent probe can be monitored and the presence of various phases of the surrounding lipid bilayer membranes can be detected. This study highlights the important differences in orientation and location and therefore in efficiency between the probes when they are used in fluorescence microscopy to screen various lipid bilayer membrane phases. Dependent on the lipid composition, the angle between the transition state dipole moments of both probes and the normal to the membrane are found to deviate clearly from 90{\deg}. It is seen that the DiI-C18(5) probe is located in the headgroup region of the SM:Chol mixture, in close contact with water molecules. A fluorescence anisotropy study indicates also that DiI-C18(5) gives rise to a distinctive behavior in the SM:Chol membrane compared to the other considered membranes. The latter behavior has not been seen for the studied BODIPY probe, which is located deeper in the membrane., Comment: 32 pages, 8 figures
- Published
- 2019
- Full Text
- View/download PDF
10. Macrophomina Crown and Root Rot of Pistachio in California
- Author
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Nouri, Mohamed T, Lawrence, Daniel P, Kallsen, Craig E, and Trouillas, Florent P
- Subjects
Agricultural ,Veterinary and Food Sciences ,Plant Biology ,Biological Sciences ,pistachio ,crown rot ,root rot ,Macrophomina phaseolina ,pathogenicity ,Pistachio ,Agricultural ,veterinary and food sciences ,Biological sciences - Abstract
In this study, declining pistachio rootstocks were detected in newly planted commercial pistachio orchards in Kern County, California. Symptoms were characterized by wilted foliage combined with crown rot in the rootstock. From diseased trees, 42 isolates were obtained, and all had similar cultural and morphological characteristics of Macrophominaphaseolina. Analyses of nucleotide sequences of three gene fragments, the internal transcribed spacer region (ITS1-5.8S-ITS2), partial sequences of β-tubulin, and translation elongation factor 1-α (TEF1) confirmed this identification, and 20 representative isolates are presented in the phylogenetic study. Testing of Koch's postulates showed that M.phaseolina, when inoculated to stems and roots of the pistachio rootstocks using mycelial plugs or a microsclerotial suspension, is indeed pathogenic to this host. The widely used clonal University of California Berkeley I (UCBI) rootstock appeared highly susceptible to M. phaseolina, suggesting that this pathogen is an emerging threat to the production of pistachio in California. This study confirmed the association of M.phaseolina with the decline of pistachio trees and represents the first description of this fungus as a crown rot-causing agent of pistachio in California.
- Published
- 2020
11. Anti-inflammatory effect of interleukin-6 highly enriched in secretome of two clinically relevant sources of mesenchymal stromal cells
- Author
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Marianne Dedier, Brice Magne, Muriel Nivet, Sébastien Banzet, and Marina Trouillas
- Subjects
mesenchymal stromal cells ,priming ,extracellular vesicles ,secretome ,interleurkin-6 ,wound healing ,Biology (General) ,QH301-705.5 - Abstract
Despite several advances in the field of regenerative medicine, clinical management of extensive skin wounds or burns remains a major therapeutic issue. During the past few years, Mesenchymal Stromal Cells (MSCs) have emerged as a novel therapeutic tool to promote tissue repair through their anti-inflammatory, pro-trophic and pro-remodeling effects. They exert their biological activity mainly via the secretion of soluble bioactive molecules such as cytokines, growth factors, proteins and microRNAs which can be encapsulated within extracellular vesicles (EV). The recent discovery of their high plasticity to external stimuli has fostered the development of new targeted therapies known as priming strategies, to enhance their potential. Our team recently showed that Interleukin-1β (IL-1β)-primed gingival MSCs promote wound healing and epidermal engraftment in vitro, and in vivo through their secreted products that contain extracellular vesicles. In the present work, we investigated whether two common sources of MSCs, gingiva and bone marrow, could respond similarly to IL-1β to favor pro-healing capabilities of their secretome. We showed that both primed-MSC sources, or their related secreted products, are able to reduce inflammation in LPS-challenged human monocytic THP-1 cell line. IL-1β priming enhanced MSC secretion of wound healing-related growth factors, cytokines and miRNAs in both sources. Among them, interleukin 6 was shown to be involved in the anti-inflammatory effect of MSC secreted products. Overall, these results underline the pro-healing properties of both MSC sources and their secretome upon IL-1β priming and their potential to improve the current medical treatment of severe wounds.
- Published
- 2023
- Full Text
- View/download PDF
12. Taxonomy and multi-locus phylogeny of cylindrocarpon-like species associated with diseased roots of grapevine and other fruit and nut crops in California
- Author
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Lawrence, DP, Nouri, MT, and Trouillas, FP
- Subjects
Biological Sciences ,Ecology ,Evolutionary Biology ,Microbiology ,Plant Biology ,Nectriaceae ,black foot disease ,new taxa ,systematics ,Evolutionary biology - Abstract
Black foot disease is a common and destructive root disease of grapevine caused by a multitude of cylindrocarpon-like fungi in many viticultural areas of the world. This study identified 12 cylindrocarpon-like fungal species across five genera associated with black foot disease of grapevine and other diverse root diseases of fruit and nut crops in the Central Valley Region of California. Morphological observations paired with multi-locus sequence typing of four loci, internal transcribed spacer region of nuclear rDNA ITS1-5.8S-ITS2 (ITS), beta-tubulin (TUB2), translation elongation factor 1-alpha (TEF1), and histone (HIS), revealed 10 previously described species; Campylocarpon fasciculare, Dactylonectria alcacerensis, D. ecuadoriensis, D. macrodidyma, D. novozelandica, D. torresensis, D. valentina, Ilyonectria capensis, I. liriodendri, I. robusta, and two new species, Neonectria californica sp. nov., and Thelonectria aurea sp. nov. Phylogenetic analyses of the ITS+TUB2+TEF1 combined dataset, a commonly employed dataset used to identify filamentous ascomycete fungi, was unable to assign some species, with significant support, in the genus Dactylonectria, while all other species in other genera were confidently identified. The HIS marker was essential either singly or in conjunction with the aforementioned genes for accurate identification of most Dactylonectria species. Results from isolations of diseased plant tissues revealed potential new host associations for almost all fungi recovered in this study. This work is the basis for future studies on the epidemiology and biology of these important and destructive plant pathogens.
- Published
- 2019
13. Taxonomic revision and multi-locus phylogeny of the North American clade of Ceratocystis
- Author
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Holland, LA, Lawrence, DP, Nouri, MT, Travadon, R, Harrington, TC, and Trouillas, FP
- Subjects
Biological Sciences ,Ecology ,Evolutionary Biology ,Genetics ,Plant Biology ,Ceratocystidaceae ,Ceratocystis canker ,almond ,new species ,taxonomy ,Evolutionary biology ,Microbiology - Abstract
The North American clade (NAC) of Ceratocystis includes pathogenic species that infect a wide range of woody hosts. Previous phylogenetic analyses have suggested that this clade includes cryptic species and a paraphyletic C. variospora. In this study, we used morphological data and phylogenetic analyses to characterize NAC taxa, including Ceratocystis isolates causing a serious disease of almond trees in California. Phylogenetic analyses based on six gene regions supported two new species of Ceratocystis. Ceratocystis destructans is introduced as the species causing severe damage to almond trees in California, and it has also been isolated from wounds on Populus and Quercus in Iowa. It is morphologically similar to C. tiliae, a pathogen on Tilia and the most recently characterized species in the NAC. Ceratocystis betulina collected from Betula platyphylla in Japan is also newly described and is the sister taxon to C. variospora. Our six-locus phylogenetic analyses and morphological characterization resolved several cryptic species in the NAC.
- Published
- 2019
14. Genomic Sequence Data of Bacterial Isolates from Pistachio Trees and Other Woody Plants in California Are Inconsistent with the Role of Rhodococcus as the Causative Agent of Pistachio Bushy Top Syndrome
- Author
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Brendan K. Riely, Mohamed T. Nouri, Kashif Riaz, Muhammad Rizwan Tufail, Yunpeng Gai, Noelia Carrasquilla, Amna Fayyaz, Peter L. Chang, Johan H. J. Leveau, Douglas R. Cook, and Florent P. Trouillas
- Subjects
microbial genomics ,PBTS ,pistachio ,Rhodococcus ,Plant culture ,SB1-1110 ,Botany ,QK1-989 - Abstract
Pistachio bushy top syndrome (PBTS) is a serious problem for pistachio growers in the western United States, but the cause of this disorder remains controversial. Recently, it was proposed that the Rhodococcus species R. fascians and R. corynebacterioides caused PBTS outbreaks in 2011 and 2015. To investigate the association of Rhodococcus spp. with PBTS in California's pistachio-growing region, Rhodococcus-like isolates were collected from diverse hosts and environments, including pistachio nurseries and orchards. Whole genome sequence analysis of 231 isolates revealed their evolutionary relationships and identified six Rhodococcus species. Combined with data on geography and host of origin, the data reveal that Rhodococcus generally, and R. fascians specifically, is ubiquitous in nature, frequently occurring in both symptomatic and asymptomatic pistachio trees and on other woody and native species. Core gene and single nucleotide polymorphism-based phylogenies and pangenome analyses differentiate R. fascians into distinct genotypes. Although we found examples of common genotypes shared between nurseries and orchards, the observed patterns are most consistent with an environmental source of strains and do not support a scenario in which individual nurseries are point sources of Rhodococcus. Moreover, none of the collected strains harbored known virulence genes, calling into question the role of these common environmental bacteria in causing PBTS. [Figure: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
- Published
- 2022
- Full Text
- View/download PDF
15. Molecular phylogeny of Cytospora species associated with canker diseases of fruit and nut crops in California, with the descriptions of ten new species and one new combination.
- Author
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Lawrence, Daniel P, Holland, Leslie A, Nouri, Mohamed T, Travadon, Renaud, Abramians, Ara, Michailides, Themis J, and Trouillas, Florent P
- Subjects
Cytospora canker ,Cytosporaceae ,Diaporthales ,multigene phylogeny ,new taxa ,taxonomy ,Microbiology - Abstract
Cytospora species are destructive canker and dieback pathogens of woody hosts in natural and agroecosystems around the world. In this genus, molecular identification has been limited due to the paucity of multi-locus sequence typing studies and the lack of sequence data from type specimens in public repositories, stalling robust phylogenetic reconstructions. In most cases a morphological species concept could not be applied due to the plasticity of characters and significant overlap of morphological features such as spore dimensions and fruiting body characters. In this study, we employed a molecular phylogenetic framework with the inclusion of four nuclear loci (ITS, translation elongation factor 1-alpha, actin, and beta-tubulin) to unveil the biodiversity and taxonomy of this understudied important genus of plant pathogens. Phylogenetic inferences based on 150 Californian isolates revealed 15 Cytospora species associated with branch and twig cankers and dieback of almond, apricot, cherry, cottonwood, olive, peach, pistachio, plum, pomegranate, and walnut trees in California. Of the 15 species recovered in this study, 10 are newly described and typified, in addition to one new combination. The pathogenic status of the newly described Cytospora species requires further investigation as most species were associated with severe dieback and decline of diverse and economically important fruit and nut crops in California.
- Published
- 2018
16. Aggressive pituitary tumours and pituitary carcinomas
- Author
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Raverot, Gérald, Ilie, Mirela Diana, Lasolle, Hélène, Amodru, Vincent, Trouillas, Jacqueline, Castinetti, Frédéric, and Brue, Thierry
- Published
- 2021
- Full Text
- View/download PDF
17. GHRH secretion from a pancreatic neuroendocrine tumor causing gigantism in a patient with MEN1
- Author
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Vinaya Srirangam Nadhamuni, Donato Iacovazzo, Jane Evanson, Anju Sahdev, Jacqueline Trouillas, Lorraine McAndrew, Tom R Kurzawinski, David Bryant, Khalid Hussain, Satya Bhattacharya, and Márta Korbonits
- Subjects
Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
A male patient with a germline mutation in MEN1 presented at the age of 18 with classical features of gigantism. Previously, he had undergone resection of an insulin-secreting pancreatic neuroendocrine tumour (pNET) at the age of 10 years and had subtotal parathyroidectomy due to primary hyperparathyroidism at the age of 15 years. He was found to have significantly elevated serum IGF-1, GH, GHRH and calcitonin levels. Pituitary MRI showed an overall bulky gland with a 3 mm hypoechoic area. Abdominal MRI showed a 27 mm mass in the head of the pancreas and a 6 mm lesion in the tail. Lanreotide-Autogel 120 mg/month reduced GHRH by 45% and IGF-1 by 20%. Following pancreaticoduodenectomy, four NETs were identified with positive GHRH and calcitonin staining and Ki-67 index of 2% in the largest lesion. The pancreas tail lesion was not removed. Post-operatively, GHRH and calcitonin levels were undetectable, IGF-1 levels normalised and GH suppressed normally on glucose challenge. Post-operative fasting glucose and HbA1c levels have remained normal at the last check-up. While adolescent-onset cases of GHRH-secreting pNETs have been described, to the best of our knowledge, this is the first reported case of ectopic GHRH in a paediatric setting leading to gigantism in a patient with MEN1. Our case highlights the importance of distinguishing between pituitary and ectopic causes of gigantism, especially in the setting of MEN1, where paediatric somatotroph adenomas causing gigantism are extremely rare.
- Published
- 2021
- Full Text
- View/download PDF
18. Complete Remission in Paralytic Late Tick-Borne Neurological Disease Comprising Mixed Involvement of Borrelia, Babesia, Anaplasma, and Bartonella: Use of Long-Term Treatments with Antibiotics and Antiparasitics in a Series of 10 Cases
- Author
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Paul Trouillas and Michel Franck
- Subjects
late tick-borne related neurological deficit ,Borrelia burgdorferi sensu lato ,Babesia ,long-term treatment ,Therapeutics. Pharmacology ,RM1-950 - Abstract
This study aimed to demonstrate that severe neurological motor deficits in the context of late tick-borne disease with mixed microorganism involvement are eligible for long-term combined antibiotic/antiparasitic treatments. The inclusion criteria were: 1. neurological limb paralysis with a disability score >4 according to the EDSS Kurtzke disability scale; 2. serological tests pointing to an involvement of the main tick-borne microorganisms Borrelia burgdorferi s.l., Babesia, Anaplasma, and Bartonella; 3. a general disease for more than 6 months with fatigue, pain and subjective cognitive deficit. The patients were administered long-term treatments with repeated cycles (at least three) of 35-day IV ceftriaxone and repeated oral regimens of azithromycin–doxycycline and azithromycin–doxycycline–rifampicin. For Babesia, repeated courses of atovaquone–azithromycin were administered. Ten patients had intractable or severe motor deficits before treatment in the context of Borrelia (two cases) Borrelia–Babesia (four cases), Borrelia–Babesia–Anaplasma (two cases), Borrelia–Babesia–Anaplasma–Bartonella (one case) and Babesia–Anaplasma (one case). For several months, five had been in wheelchairs, and four had been walking with sticks. Seven patients out of 10 (70%) showed complete remission after a mean active treatment duration of 20.1 + 6.6 months, with a mean number of 4 ceftriaxone cycles. Three patients showed an initial remission but suffered secondary antibiotic/antiparasitic-resistant motor recurrences. Among the nine patients with Borrelia serologic positivity, treatments obtained complete remission in seven cases (77%). The findings of this ten-case series suggest the usefulness of long-term antibiotic/antiparasitic treatments in patients with severe late tick-borne neurological deficits with highly significant elements of tick-borne involvement.
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- 2023
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19. Para-Substituted α‑Phenyl‑N-tert-butyl Nitrones: Spin-Trapping, Redox and Neuroprotective Properties
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Anaïs Deletraz, Béatrice Tuccio, Julien Roussel, Maud Combes, Catherine Cohen-Solal, Paul-Louis Fabre, Patrick Trouillas, Michel Vignes, Noelle Callizot, and Grégory Durand
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Chemistry ,QD1-999 - Published
- 2020
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20. Pituitary neuroendocrine tumors (PitNETs): nomenclature evolution, not clinical revolution
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Asa, Sylvia L., Asioli, Sofia, Bozkurt, Suheyla, Casar-Borota, Olivera, Chinezu, Laura, Comunoglu, Nil, Cossu, Giulia, Cusimano, Michael, Delgrange, Etienne, Earls, Peter, Ezzat, Shereen, Gazioglu, Nurperi, Grossman, Ashley, Guaraldi, Federica, Hickman, Richard A., Ikeda, Hidetoshi, Jaffrain-Rea, Marie-Lise, Karavitaki, Niki, Kraljević, Ivana, La Rosa, Stefano, Manojlović-Gačić, Emilija, Maartens, Niki, McCutcheon, Ian E., Messerer, Mahmoud, Mete, Ozgur, Nishioka, Hiroshi, Oz, Buge, Pakbaz, Sara, Pekmezci, Melike, Perry, Arie, Reiniger, Lilla, Roncaroli, Federico, Saeger, Wolfgang, Söylemezoğlu, Figen, Tachibana, Osamu, Trouillas, Jacqueline, Turchini, John, Uccella, Silvia, Villa, Chiara, Yamada, Shozo, and Yarman, Sema
- Published
- 2020
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21. Are aggressive pituitary tumors and carcinomas two sides of the same coin? Pathologists reply to clinician’s questions
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Trouillas, Jacqueline, Jaffrain-Rea, Marie-Lise, Vasiljevic, Alexandre, Dekkers, Olaf, Popovic, Vera, Wierinckx, Anne, McCormack, Ann, Petersenn, Stephan, Burman, Pia, Raverot, Gérald, and Villa, Chiara
- Published
- 2020
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22. A standardised diagnostic approach to pituitary neuroendocrine tumours (PitNETs): a European Pituitary Pathology Group (EPPG) proposal
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Villa, C., Vasiljevic, A., Jaffrain-Rea, M. L., Ansorge, O., Asioli, S., Barresi, V., Chinezu, L., Gardiman, M. P., Lania, A., Lapshina, A. M., Poliani, L., Reiniger, L., Righi, A., Saeger, W., Soukup, J., Theodoropoulou, M., Uccella, S., Trouillas, J., and Roncaroli, F.
- Published
- 2019
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23. The Impact of Plasma Membrane Lipid Composition on Flagellum-Mediated Adhesion of Enterohemorrhagic Escherichia coli
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Hélène Cazzola, Laurine Lemaire, Sébastien Acket, Elise Prost, Luminita Duma, Marc Erhardt, Petra Čechová, Patrick Trouillas, Fady Mohareb, Claire Rossi, and Yannick Rossez
- Subjects
adhesins ,flagella ,lipid rafts ,phospholipids ,Microbiology ,QR1-502 - Abstract
ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of foodborne gastrointestinal illness. The adhesion of EHEC to host tissues is the first step enabling bacterial colonization. Adhesins such as fimbriae and flagella mediate this process. Here, we studied the interaction of the bacterial flagellum with the host cell’s plasma membrane using giant unilamellar vesicles (GUVs) as a biologically relevant model. Cultured cell lines contain many different molecular components, including proteins and glycoproteins. In contrast, with GUVs, we can characterize the bacterial mode of interaction solely with a defined lipid part of the cell membrane. Bacterial adhesion on GUVs was dependent on the presence of the flagellar filament and its motility. By testing different phospholipid head groups, the nature of the fatty acid chains, or the liposome curvature, we found that lipid packing is a key parameter to enable bacterial adhesion. Using HT-29 cells grown in the presence of polyunsaturated fatty acid (α-linolenic acid) or saturated fatty acid (palmitic acid), we found that α-linolenic acid reduced adhesion of wild-type EHEC but not of a nonflagellated mutant. Finally, our results reveal that the presence of flagella is advantageous for the bacteria to bind to lipid rafts. We speculate that polyunsaturated fatty acids prevent flagellar adhesion on membrane bilayers and play a clear role for optimal host colonization. Flagellum-mediated adhesion to plasma membranes has broad implications for host-pathogen interactions. IMPORTANCE Bacterial adhesion is a crucial step to allow bacteria to colonize their hosts, invade tissues, and form biofilm. Enterohemorrhagic Escherichia coli O157:H7 is a human pathogen and the causative agent of diarrhea and hemorrhagic colitis. Here, we use biomimetic membrane models and cell lines to decipher the impact of lipid content of the plasma membrane on enterohemorrhagic E. coli flagellum-mediated adhesion. Our findings provide evidence that polyunsaturated fatty acid (α-linolenic acid) inhibits E. coli flagellar adhesion to the plasma membrane in a mechanism separate from its antimicrobial and anti-inflammatory functions. In addition, we confirm that cholesterol-enriched lipid microdomains, often called lipid rafts, are important in bacterial adhesion. These findings demonstrate that plasma membrane adhesion via bacterial flagella play a significant role for an important human pathogen. This mechanism represents a promising target for the development of novel antiadhesion therapies.
- Published
- 2020
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24. Spore dispersal of Eutypella species under desert grape-growing conditions of southern California
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José Ramón ÚRBEZ-TORRES, Carmen GISPERT, and Florent Pierre TROUILLAS
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Canker ,Diatrypaceae ,epidemiology ,Eutypa ,Eutypella ,grapevine trunk diseases ,Botany ,QK1-989 - Abstract
The seasonal abundance of Diatrypaceae spores was studied in southern California’s desert table grape-growing region of Coachella Valley. Glass microscope slides covered with petroleum jelly were placed in a mature cv. Mid-Night Beauty® vineyard, and collected weekly from September 2006 to May 2009 (1400 samples for 140 consecutive weeks). Overall, Diatrypaceae-like colonies were recorded from Petri plates after processing spore traps in 93 (66%) of 140 weeks. Phylogenetic analyses showed Eutypella citricola and Eutypella microtheca to be the Diatrypaceae spp. captured from the spore traps. Though spores were captured throughout each year, their incidence varied among the different seasons. The greatest number of Eutypella spores were captured in autumn (38.7% of the total) followed by winter (30.6%), summer (19.7%), and spring (11%). The greatest numbers of spores were captured in October each year (15.7%) and least in June (1%). Eutypella spore release was correlated with rainfall only in 26 (28%) of the 93 weeks that spores were captured during the study. Analysis of diseased samples collected from the cv. Mid-Night Beauty® vineyard showed that E. citricola, E. microtheca and E. scoparia were the most prevalent fungi isolated from cankers. A pathogenicity study showed that E. citricola and E. microtheca isolates collected from spore traps caused larger vascular necrosis than the non-inoculated controls, indicating their role as pathogens on grapevines. This study has demonstrated Eutypella spp. to play an important role in grapevine health under desert growing conditions of southern California. In addition, and contrary to what it is largely accepted, results from this research suggest that Diatrypaceae spore release can occur in the absence of precipitation. This study expands current knowledge on epidemiology of Diatrypaceae spp. other than Eutypa lata, and provides important information for enhancing control strategies against grapevine trunk diseases under desert growing conditions.
- Published
- 2020
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25. Molecular phylogeny of Cytospora species associated with canker diseases of fruit and nut crops in California, with the descriptions of ten new species and one new combination
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Daniel P. Lawrence, Leslie A. Holland, Mohamed T. Nouri, Renaud Travadon, Ara Abramians, Themis J. Michailides, and Florent P. Trouillas
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Cytosporaceae ,Cytospora canker ,Diaporthales ,multigene phylogeny ,new taxa ,taxonomy ,Botany ,QK1-989 - Abstract
Abstract Cytospora species are destructive canker and dieback pathogens of woody hosts in natural and agroecosystems around the world. In this genus, molecular identification has been limited due to the paucity of multi-locus sequence typing studies and the lack of sequence data from type specimens in public repositories, stalling robust phylogenetic reconstructions. In most cases a morphological species concept could not be applied due to the plasticity of characters and significant overlap of morphological features such as spore dimensions and fruiting body characters. In this study, we employed a molecular phylogenetic framework with the inclusion of four nuclear loci (ITS, translation elongation factor 1-alpha, actin, and beta-tubulin) to unveil the biodiversity and taxonomy of this understudied important genus of plant pathogens. Phylogenetic inferences based on 150 Californian isolates revealed 15 Cytospora species associated with branch and twig cankers and dieback of almond, apricot, cherry, cottonwood, olive, peach, pistachio, plum, pomegranate, and walnut trees in California. Of the 15 species recovered in this study, 10 are newly described and typified, in addition to one new combination. The pathogenic status of the newly described Cytospora species requires further investigation as most species were associated with severe dieback and decline of diverse and economically important fruit and nut crops in California.
- Published
- 2018
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26. Temporal susceptibility of almond pruning wounds to infection by fungal canker pathogens in California
- Author
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Leslie A. Holland, Renaud Travadon, Daniel P. Lawrence, Rosa Jaime‐Frias, Mohamed T. Nouri, Mohammad Sahtout, and Florent P. Trouillas
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Genetics ,Plant Science ,Horticulture ,Agronomy and Crop Science - Published
- 2022
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27. A common classification framework for neuroendocrine neoplasms: an International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal
- Author
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Rindi, Guido, Klimstra, David S., Abedi-Ardekani, Behnoush, Asa, Sylvia L., Bosman, Frederik T., Brambilla, Elisabeth, Busam, Klaus J., de Krijger, Ronald R., Dietel, Manfred, El-Naggar, Adel K., Fernandez-Cuesta, Lynnette, Klöppel, Günter, McCluggage, W. Glenn, Moch, Holger, Ohgaki, Hiroko, Rakha, Emad A., Reed, Nicholas S., Rous, Brian A., Sasano, Hironobu, Scarpa, Aldo, Scoazec, Jean-Yves, Travis, William D., Tallini, Giovanni, Trouillas, Jacqueline, van Krieken, J. Han, and Cree, Ian A.
- Published
- 2018
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28. Diagnostic challenges and management of a patient with acromegaly due to ectopic growth hormone-releasing hormone secretion from a bronchial carcinoid tumour
- Author
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Nikolaos Kyriakakis, Jacqueline Trouillas, Mary N Dang, Julie Lynch, Paul Belchetz, Márta Korbonits, and Robert D Murray
- Subjects
Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
A male patient presented at the age of 30 with classic clinical features of acromegaly and was found to have elevated growth hormone levels, not suppressing during an oral glucose tolerance test. His acromegaly was originally considered to be of pituitary origin, based on a CT scan, which was interpreted as showing a pituitary macroadenoma. Despite two trans-sphenoidal surgeries, cranial radiotherapy and periods of treatment with bromocriptine and octreotide, his acromegaly remained active clinically and biochemically. A lung mass was discovered incidentally on a chest X-ray performed as part of a routine pre-assessment for spinal surgery 5 years following the initial presentation. This was confirmed to be a bronchial carcinoid tumour, which was strongly positive for growth hormone-releasing hormone (GHRH) and somatostatin receptor type 2 by immunohistochemistry. The re-examination of the pituitary specimens asserted the diagnosis of pituitary GH hyperplasia. Complete resolution of the patient’s acromegaly was achieved following right lower and middle lobectomy. Seventeen years following the successful resection of the bronchial carcinoid tumour the patient remains under annual endocrine follow-up for monitoring of the hypopituitarism he developed after the original interventions to his pituitary gland, while there has been no evidence of active acromegaly or recurrence of the carcinoid tumour. Ectopic acromegaly is extremely rare, accounting for
- Published
- 2017
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29. Development of PCR-Based Assays for Rapid and Reliable Detection and Identification of Canker-Causing Pathogens from Symptomatic Almond Trees
- Author
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Herve F. Avenot, Rosa Jaime-Frias, Renaud Travadon, Leslie A. Holland, Daniel P. Lawrence, and Florent P. Trouillas
- Subjects
Plant Science ,DNA, Fungal ,Polymerase Chain Reaction ,Prunus dulcis ,Agronomy and Crop Science ,Phylogeny ,Plant Diseases - Abstract
Trunk and scaffold canker diseases (TSCDs) of almond cause significant yield and tree losses and reduce the lifespan of orchards. In California, several pathogens cause TSCDs, including Botryosphaeriaceae, Ceratocystis destructans, Eutypa lata, Collophorina hispanica, Pallidophorina paarla, Cytospora, Diaporthe, and Phytophthora spp. Field diagnosis of TSCDs is challenging because symptom delineation among the diseases is not clear. Accurate diagnosis of the causal species requires detailed examination of symptoms and subsequent isolation on medium and identification using morphological criteria and subsequent confirmation using molecular tools. The process is time-consuming and difficult, particularly as morphological characteristics are variable and overlap among species. To facilitate diagnosis of TSCD, we developed PCR assays using 23 species-specific primers designed by exploiting sequence differences in the translation elongation factor, β-tubulin, or internal transcribed spacer gene. Using genomic DNA from pure cultures of each fungal and oomycete species, each primer pair successfully amplified a single DNA fragment from the target pathogen but not from selected nontarget pathogens or common endophytes. Although 10-fold serial dilution of fungal DNA extracted from either pure cultures or infected wood samples detected as little as 0.1 pg of DNA sample, consistent detection required 10 ng of pathogen DNA from mycelial samples or from wood chips or drill shavings from artificially or naturally infected almond wood samples with visible symptoms. The new PCR assay represents an improved tool for diagnostic laboratories and will be critical to implement effective disease surveillance and control measures.
- Published
- 2022
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30. Genomic Sequence Data of Bacterial Isolates from Pistachio Trees and Other Woody Plants in California Are Inconsistent with the Role of Rhodococcus as the Causative Agent of Pistachio Bushy Top Syndrome
- Author
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Florent P. Trouillas, Johan H. J. Leveau, M. T. Nouri, Kashif Riaz, Muhammad Rizwan Tufail, Miss Amna Fayyaz, Peter L. Chang, Douglas R. Cook, Brendan K. Riely, Yunpeng Gai, and Noelia Carrasquilla
- Subjects
Microbiology (medical) ,Data sequences ,Immunology ,Botany ,Immunology and Allergy ,Biology ,biology.organism_classification ,Rhodococcus ,Woody plant - Abstract
Pistachio bushy top syndrome (PBTS) is a serious problem for pistachio growers in the western United States, but the cause of this disorder remains controversial. Recently, it was proposed that the Rhodococcus species R. fascians and R. corynebacterioides caused PBTS outbreaks in 2011 and 2015. To investigate the association of Rhodococcus spp. with PBTS in California's pistachio-growing region, Rhodococcus-like isolates were collected from diverse hosts and environments, including pistachio nurseries and orchards. Whole genome sequence analysis of 231 isolates revealed their evolutionary relationships and identified six Rhodococcus species. Combined with data on geography and host of origin, the data reveal that Rhodococcus generally, and R. fascians specifically, is ubiquitous in nature, frequently occurring in both symptomatic and asymptomatic pistachio trees and on other woody and native species. Core gene and single nucleotide polymorphism-based phylogenies and pangenome analyses differentiate R. fascians into distinct genotypes. Although we found examples of common genotypes shared between nurseries and orchards, the observed patterns are most consistent with an environmental source of strains and do not support a scenario in which individual nurseries are point sources of Rhodococcus. Moreover, none of the collected strains harbored known virulence genes, calling into question the role of these common environmental bacteria in causing PBTS. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
- Published
- 2022
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31. Floral Microbes Suppress Growth of Monilinia laxa with Minimal Effects on Honey Bee Feeding
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M. T. Nouri, M. Crespo, Elina L. Niño, Amber Crowley-Gall, Robert N. Schaeffer, Rachel L. Vannette, and Florent P. Trouillas
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biology ,fungi ,Biological pest control ,food and beverages ,Plant Science ,Honey bee ,biology.organism_classification ,Fungicide ,Prunus dulcis ,Horticulture ,Current management ,Pollinator ,Blight ,Agronomy and Crop Science ,Monilinia laxa - Abstract
Management of Monilinia laxa, the causal agent of brown rot blossom blight in almond (Prunus dulcis), relies heavily on the use of chemical fungicides during bloom. However, chemical fungicides can have nontarget effects on beneficial arthropods, including pollinators, and select for resistance in the pathogen of concern. Almond yield is heavily reliant on successful pollination by healthy honey bees (Apis mellifera); thus, identifying sustainable, effective, and pollinator-friendly control methods for blossom blight during bloom is desirable. Flower-inhabiting microbes could provide a natural, sustainable form of biocontrol for M. laxa, while potentially minimizing costly nontarget effects on almond pollinators and the services they provide. As pollinators are sensitive to floral microbes and their associated taste and scent cues, assessing effects of prospective biocontrol species on pollinator attraction is also necessary. Here, our objective was to isolate and identify potential biocontrol microbes from an array of agricultural and natural flowering hosts and test their efficacy in suppressing M. laxa growth in culture. Out of an initial 287 bacterial and fungal isolates identified, 56 were screened using a dual culture plate assay. Most strains reduced M. laxa growth in vitro. Ten particularly effective candidate microbes were further screened for their effect on honey bee feeding. Of the 10, nine were found to both strongly suppress M. laxa growth in culture and not reduce honey bee feeding. These promising results suggest a number of strong candidates for augmentative microbial biocontrol of brown rot blossom blight in almond with potentially minimal effects on honey bee pollination.
- Published
- 2022
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32. Identification and Characterization of Phytophthora Species Associated with Crown and Root Rot of Pistachio Trees in California
- Author
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Tyler B. Bourret, Florent P. Trouillas, and M. T. Nouri
- Subjects
Nut ,Horticulture ,fungi ,Crown (botany) ,Root rot ,food and beverages ,Subject areas ,Plant Science ,Phytophthora ,Biology ,biology.organism_classification ,Agronomy and Crop Science - Abstract
Pistachio is one of the most widely cultivated nut crops in California, with approximately 115,000 ha of bearing pistachio trees. In recent years, several orchards were identified, with declining trees leading to substantial tree losses. Symptoms included trees with poor vigor, yellowing and wilting of leaves, crown rot, and profuse gumming on the lower portion of trunks. Thirty-seven Phytophthora-like isolates were obtained from crown rot tissues in the rootstock of grafted pistachio trees and characterized by means of multilocus phylogeny comprising internal transcribed spacer rDNA, beta-tubulin, and mt cox1 sequence data. The analysis provided strong support for the delineation and identification of three Phytophthora species associated with declining pistachio trees, including P. niederhauserii, P. mediterranea, and Phytophthora taxon walnut. Pathogenicity studies in potted University of California Berkeley I (UCBI) rootstocks (clonal and seeded) confirmed that all three Phytophthora species can cause crown and root rot of pistachio, thus fulfilling Koch’s postulates. The widespread occurrence of Phytophthora crown rot in recently planted pistachio orchards and the susceptibility of UCBI rootstocks suggest this disease constitute an emerging new threat to the pistachio industry of California. To the best of our knowledge, this study is the first to report P. niederhauserii, P. mediterranea, and Phytophthora taxon walnut as causal agents of crown and root rots of pistachio.
- Published
- 2022
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33. Field Evaluation of Biological Wound Treatments for the Management of Almond, Cherry, and Grapevine Fungal Canker Diseases
- Author
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Renaud Travadon, Daniel P. Lawrence, Sampson Li, and Florent P. Trouillas
- Subjects
History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2023
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34. Pomegranate dieback caused by Lasiodiplodia gilanensis in California
- Author
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Úrbez-Torres, J. R., Hand, F. Peduto, Trouillas, F. P., and Gubler, W. D.
- Published
- 2017
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35. Tannic Acid Improves Renal Function Recovery after Renal Warm Ischemia–Reperfusion in a Rat Model
- Author
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Louise Alechinsky, Frederic Favreau, Petra Cechova, Sofiane Inal, Pierre-Antoine Faye, Cecile Ory, Raphaël Thuillier, Benoit Barrou, Patrick Trouillas, Jerome Guillard, and Thierry Hauet
- Subjects
warm ischemia ,cold ischemia ,tannic acid ,renal function recovery ,oxidative stress ,Microbiology ,QR1-502 - Abstract
Background and purpose: Ischemia−reperfusion injury is encountered in numerous processes such as cardiovascular diseases or kidney transplantation; however, the latter involves cold ischemia, different from the warm ischemia found in vascular surgery by arterial clamping. The nature and the intensity of the processes induced by ischemia types are different, hence the therapeutic strategy should be adapted. Herein, we investigated the protective role of tannic acid, a natural polyphenol in a rat model reproducing both renal warm ischemia and kidney allotransplantation. The follow-up was done after 1 week. Experimental approach: To characterize the effect of tannic acid, an in vitro model of endothelial cells subjected to hypoxia−reoxygenation was used. Key results: Tannic acid statistically improved recovery after warm ischemia but not after cold ischemia. In kidneys biopsies, 3 h after warm ischemia−reperfusion, oxidative stress development was limited by tannic acid and the production of reactive oxygen species was inhibited, potentially through Nuclear Factor erythroid-2-Related factor 2 (NRF2) activation. In vitro, tannic acid and its derivatives limited cytotoxicity and the generation of reactive oxygen species. Molecular dynamics simulations showed that tannic acid efficiently interacts with biological membranes, allowing efficient lipid oxidation inhibition. Tannic acid also promoted endothelial cell migration and proliferation during hypoxia. Conclusions: Tannic acid was able to improve renal recovery after renal warm ischemia with an antioxidant effect putatively extended by the production of its derivatives in the body and promoted cell regeneration during hypoxia. This suggests that the mechanisms induced by warm and cold ischemia are different and require specific therapeutic strategies.
- Published
- 2020
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36. Macrophomina Crown and Root Rot of Pistachio in California
- Author
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Mohamed T. Nouri, Daniel P. Lawrence, Craig E. Kallsen, and Florent P. Trouillas
- Subjects
pistachio ,crown rot ,root rot ,macrophomina phaseolina ,pathogenicity ,Botany ,QK1-989 - Abstract
In this study, declining pistachio rootstocks were detected in newly planted commercial pistachio orchards in Kern County, California. Symptoms were characterized by wilted foliage combined with crown rot in the rootstock. From diseased trees, 42 isolates were obtained, and all had similar cultural and morphological characteristics of Macrophomina phaseolina. Analyses of nucleotide sequences of three gene fragments, the internal transcribed spacer region (ITS1−5.8S−ITS2), partial sequences of β-tubulin, and translation elongation factor 1-α (TEF1) confirmed this identification, and 20 representative isolates are presented in the phylogenetic study. Testing of Koch’s postulates showed that M. phaseolina, when inoculated to stems and roots of the pistachio rootstocks using mycelial plugs or a microsclerotial suspension, is indeed pathogenic to this host. The widely used clonal University of California Berkeley I (UCBI) rootstock appeared highly susceptible to M. phaseolina, suggesting that this pathogen is an emerging threat to the production of pistachio in California. This study confirmed the association of M. phaseolina with the decline of pistachio trees and represents the first description of this fungus as a crown rot-causing agent of pistachio in California.
- Published
- 2020
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37. Sex-Related Differences in Lactotroph Tumor Aggressiveness Are Associated With a Specific Gene-Expression Signature and Genome Instability
- Author
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Anne Wierinckx, Etienne Delgrange, Philippe Bertolino, Patrick François, Philippe Chanson, Emmanuel Jouanneau, Joël Lachuer, Jacqueline Trouillas, and Gérald Raverot
- Subjects
pituitary tumors ,gene expression ,estrogen signaling ,sexual dimorphism ,chromosome ,aggressiveness ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Sex-related differences have been reported in various cancers, in particular men with lactotroph tumors have a worse prognosis than women. While the underlying mechanism of this sexual dimorphism remains unclear, it has been suggested that a lower estrogen receptor alpha expression may drive the sex differences observed in aggressive and malignant lactotroph tumors that are resistant to dopamine agonists. Based on this observation, we aimed to explore the molecular importance of the estrogen pathway through a detailed analysis of the transcriptomic profile of lactotroph tumors from 20 men and 10 women. We undertook gene expression analysis of the selected lactotroph tumors following their pathological grading using the five-tiered classification. Chromosomic alterations were further determined in 13 tumors. Functional analysis showed that there were differences between tumors from men and women in gene signatures associated with cell morphology, cell growth, cell proliferation, development, and cell movement. Hundred-forty genes showed an increased or decreased expression with a minimum 2-fold change. A large subset of those genes belonged to the estrogen receptor signaling pathway, therefore confirming the potent role of this pathway in lactotroph tumor sex-associated aggressiveness. Genes belonging to the X chromosome, such as CTAG2, FGF13, and VEGF-D, were identified as appealing candidates with a sex-linked dysregulation in lactotroph tumors. Through our comparative genomic hybridization analyses (CGH), chromosomic gain, in particular chromosome 19p, was found only in tumors from men, while deletion of chromosome 11 was sex-independent, as it was found in most (5/6) of the aggressive and malignant tumors. Comparison of transcriptomic and CGH analysis revealed four genes (CRB3, FAM138F, MATK, and STAP2) located on gained regions of chromosome 19 and upregulated in lactotroph tumors from men. MATK and STAP2 are both implicated in cell growth and are reported to be associated with the estrogen signaling pathway. Our work confirms the proposed involvement of the estrogen signaling pathway in favoring the increased aggressiveness of lactotroph tumors in men. More importantly, we highlight a number of ER-related candidate genes and further identify a series of target molecules with sex-specific expression that could contribute to the aggressive behavior of lactotroph tumors in men.
- Published
- 2018
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38. Evaluation of Pruning Wound Protection Products for the Management of Almond Canker Diseases in California
- Author
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Renaud Travadon, M. T. Nouri, Daniel P. Lawrence, L. A. Holland, and Florent P. Trouillas
- Subjects
0106 biological sciences ,Canker ,biology ,Cytospora ,food and beverages ,Plant Science ,Botryosphaeriaceae ,biology.organism_classification ,medicine.disease ,Prunus dulcis ,01 natural sciences ,Fungicides, Industrial ,Fungicide ,010602 entomology ,Horticulture ,Biological Control Agents ,Disease management (agriculture) ,medicine ,Eutypa ,Disease prevention ,Agronomy and Crop Science ,Pruning ,Plant Diseases ,010606 plant biology & botany - Abstract
Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning wounds act as major infection courts. Before this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint, and a sealant were evaluated for preventing fungal pathogen infection via pruning wounds. In four field trials conducted over two dormant seasons, 16 pruning wound treatments were tested using handheld spray applications against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide thiophanate-methyl (Topsin M; United Phosphorus, Bandra West, Mumbai, India) provided 82% overall disease prevention against four fungal pathogens. The biological control agent, Trichoderma atroviride SC1 (Vintec; Bi-PA, Londerzeel, Belgium), tested at three application rates, resulted in 90 to 93% protection of pruning wounds in field trials, and for individual pathogens ranged from 81 to 100% protection for the three rates. At the time of this publication, Vintec is being considered for registration as a biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning wounds from infection by almond canker pathogens can be achieved with a one-time spray application of thiophanate-methyl or the biocontrol T. atroviride SC1 (recommended 2 g/liter) after pruning.
- Published
- 2021
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- View/download PDF
39. Pleurostoma Decline of Olive Trees Caused byPleurostoma richardsiaein California
- Author
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Daniel P. Lawrence, Florent P. Trouillas, and M. T. Nouri
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0106 biological sciences ,0301 basic medicine ,biology ,food and beverages ,Plant Science ,Fungal pathogen ,030108 mycology & parasitology ,biology.organism_classification ,01 natural sciences ,Olive trees ,03 medical and health sciences ,Horticulture ,Pleurostoma ,Olea ,Pleurostoma richardsiae ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
A single fungal pathogen was consistently isolated from symptomatic wood of olive trees (Olea europaea) displaying branch and trunk cankers in superhigh-density orchards in the Sacramento and San Joaquin Valleys of California. Morphological characters of the pathogen included two distinct types of conidia (thick-walled, dark brown, and globose and thin-walled, hyaline, and oblong to ellipsoid) and three types of phialides, indicating a pleurostoma-like fungus. Phylogenetic results of four nuclear loci including the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) and partial sequences of the actin, beta-tubulin, and translation elongation factor 1-α genes confirmed the isolates as Pleurostoma richardsiae. Pathogenicity trials conducted in the field involving 2- to 3-year-old branches of three widely planted oil olive cultivars (Arbequina, Arbosana, and Koroneiki) satisfied Koch’s postulates and confirmed the pathogenic nature of this species to cause the decline of olive trees in California. All three cultivars were equally susceptible to Pl. richardsiae, indicating no detectable resistance to the pathogen. Additional isolations from symptomatic hosts including almond, peach, pistachio, and plum, also confirmed this species, suggesting that Pl. richardsiae is widespread in agricultural systems and should be considered an emerging pathogen of fruit and nut crops in California.
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- 2021
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40. cis–trans Isomerization of silybins A and B
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Michaela Novotná, Radek Gažák, David Biedermann, Florent Di Meo, Petr Marhol, Marek Kuzma, Lucie Bednárová, Kateřina Fuksová, Patrick Trouillas, and Vladimír Křen
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2,3-cis-silybin ,10,11-cis-silybin ,isomerization ,silibinin ,silybin ,silymarin ,Science ,Organic chemistry ,QD241-441 - Abstract
Methods were developed and optimized for the preparation of the 2,3-cis- and the 10,11-cis-isomers of silybin by the Lewis acid catalyzed (BF3∙OEt2) isomerization of silybins A (1a) and B (1b) (trans-isomers). The absolute configuration of all optically pure compounds was determined by using NMR and comparing their electronic circular dichroism data with model compounds of known absolute configurations. Mechanisms for cis–trans-isomerization of silybin are proposed and supported by quantum mechanical calculations.
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- 2014
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41. Lignin Modification Supported by DFT-Based Theoretical Study as a Way to Produce Competitive Natural Antioxidants
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Liga Lauberte, Gabin Fabre, Jevgenija Ponomarenko, Tatiana Dizhbite, Dmitry V. Evtuguin, Galina Telysheva, and Patrick Trouillas
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lignins ,antioxidant activity ,molecular rationalization ,modification ,stabilizers for polymers ,Organic chemistry ,QD241-441 - Abstract
The valorization of lignins as renewable aromatic feedstock is of utmost importance in terms of the use of sustainable resources. This study provides a deductive approach towards market-oriented lignin-derived antioxidants by ascertaining the direct effect of different structural features of lignin on the reactivity of its phenolic OH groups in the radical scavenging reactions. The antioxidant activity of a series of compounds, modeling lignin structural units, was experimentally characterized and rationalized, using thermodynamic descriptors. The calculated O−H bond dissociation enthalpies (BDE) of characteristic lignin subunits were used to predict the modification pathways of technical lignins. The last ones were isolated by soda delignification from different biomass sources and their oligomeric fractions were studied as a raw material for modification and production of optimized antioxidants. These were characterized in terms of chemical structure, molecular weight distribution, content of the functional groups, and the antioxidant activity. The developed approach for the targeted modification of lignins allowed the products competitive with two commercial synthetic phenolic antioxidants in both free radical scavenging and stabilization of thermooxidative destruction of polyurethane films.
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- 2019
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42. Development of the sensorimotor cortex in the human fetus: a morphological description
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Afif, Afif, Trouillas, Jacqueline, and Mertens, Patrick
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- 2015
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43. Dothiorella and Spencermartinsia, new species and records from grapevines in Australia
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Pitt, Wayne M., Úrbez-Torres, José Ramón, and Trouillas, Florent P.
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- 2015
- Full Text
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44. Olive Twig and Branch Dieback in California Caused by Cytospora oleicola and the Newly Described Species Cytospora olivarum sp. nov
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Florent P. Trouillas, Daniel P. Lawrence, José Ramón Úrbez-Torres, and Francesca Peduto Hand
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0106 biological sciences ,0301 basic medicine ,Pathogen detection ,Cytospora ,Plant Science ,030108 mycology & parasitology ,Biology ,biology.organism_classification ,Pathogenicity ,01 natural sciences ,Twig ,03 medical and health sciences ,Horticulture ,Intergenic region ,Taxonomy (biology) ,Fungal morphology ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
Field surveys conducted throughout California olive-growing regions in 2008 and 2009 resulted in a collection of 101 Cytospora-like isolates from olive twig and branch dieback symptoms. Cytospora isolates were isolated from multiple cvs. in different olive orchards in Fresno, Madera, Merced, Napa, Riverside, Santa Barbara, Sonoma, Tulare, and Ventura counties. Taxonomic studies of macro- and microscopic structures along with multigene phylogenetic analyses of the internal transcribed spacer region, including the 5.8S rDNA (ITS1–5.8S–ITS2), and fragments of the translation elongation factor 1-α, beta-tubulin, and actin genes identified two species, Cytospora oleicola and C. olivarum sp. nov. Pathogenicity studies conducted in mature olive trees cvs. Manzanillo and Sevillano showed both species to be pathogenic and able to cause vascular necrosis and cankers in olive branches. This study adds to the current knowledge on the etiology of olive twig and branch dieback and provides new important information for the development of effective control strategies against canker diseases affecting olive in California.
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- 2020
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45. Comparative Profiling of Wood Canker Pathogens from Spore Traps and Symptomatic Plant Samples Within California Almond and Walnut Orchards
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Israel Jiménez Luna, David Doll, Vanessa E. T. M. Ashworth, Florent P. Trouillas, and Philippe E. Rolshausen
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Ascomycota ,Juglans ,Plant Science ,Spores, Fungal ,Agronomy and Crop Science ,Prunus dulcis ,Wood ,Ceratocystis - Abstract
Fungi causing wood canker diseases are major factors limiting productivity and longevity of almond and walnut orchards. The goal of this study was to compare pathogen profiles from spore traps with those of plant samples collected from symptomatic almond and walnut trees and assess if profiles could be influenced by orchard type and age, rainfall amount and frequency, and/or neighboring trees. Three almond orchards and one walnut orchard with different characteristics were selected for this study. Fungal inoculum was captured weekly from nine trees per orchard using a passive spore-trapping device, during a 30-week period in the rainy season (October to April) and for two consecutive years. Fungal taxa identified from spore traps were compared with a collection of fungal isolates obtained from 61 symptomatic wood samples collected from the orchards. Using a culture-dependent approach coupled with molecular identification, we identified 18 known pathogenic species from 10 fungal genera (Ceratocystis destructans, Collophorina hispanica, Cytospora eucalypti, Diaporthe ampelina, Diaporthe chamaeropis/rhusicola, Diaporthe eres, Diaporthe novem, Diplodia corticola, Diplodia mutila, Diplodia seriata, Dothiorella iberica, Dothiorella sarmentorum, Dothiorella viticola, Eutypa lata, Neofusicoccum mediterraneum, Neofusicoccum parvum, Neoscytalidium dimidiatum, and Pleurostoma richardsiae), plus two unidentified Cytospora and Diaporthe species. However, only four species were identified with both methods (Diplodia mutila, Diplodia seriata, Dothiorella Iberica, and E. lata), albeit not consistently across orchards. Our results demonstrate a clear disparity between the two diagnostic methods and caution against using passive spore traps to predict disease risks. In particular, the spore trap approach failed to capture: insect-vectored pathogens such as Ceratocystis destructans that were often recovered from almond trunk and scaffold; Diaporthe chamaeropis/rhusicola commonly isolated from wood samples likely because Diaporthe species have a spatially restricted dispersal mechanism, as spores are exuded in a cirrus; and pathogenic species with low incidence in wood samples such as P. richardsiae and Collophorina hispanica. We propose that orchard inoculum is composed of both endemic taxa that are characterized by frequent and repeated trapping events from the same trees and isolated from plant samples, as well as immigrant taxa characterized by rare trapping events. We hypothesize that host type, orchard age, precipitation, and alternative hosts at the periphery of orchards are factors that could affect pathogen profile. We discuss the limitations and benefits of our methodology and experimental design to develop guidelines and prediction tools for fungal wood canker diseases in California orchards.
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- 2022
46. In Search of a Prognostic Classification of Endocrine Pituitary Tumors
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Trouillas, Jacqueline
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- 2014
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47. Floral Microbes Suppress Growth of
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Amber, Crowley-Gall, Florent P, Trouillas, Elina L, Niño, Robert N, Schaeffer, Mohamed T, Nouri, Maria, Crespo, and Rachel L, Vannette
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Ascomycota ,Antibiosis ,Animals ,Flowers ,Prospective Studies ,Bees ,Pollination ,Prunus dulcis - Abstract
Management of
- Published
- 2021
48. Identification and Characterization of Neofabraea kienholzii and Phlyctema vagabunda Causing Leaf and Shoot Lesions of Olive in California
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Renaud Travadon, Danielle Lightle, Juan Moral, Daniel P. Lawrence, B. J. Aegerter, Florent P. Trouillas, and M. T. Nouri
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biology ,food and beverages ,Plant Science ,biology.organism_classification ,Olive trees ,Horticulture ,Intergenic region ,Shoot ,Cultivar ,Internal transcribed spacer ,San Joaquin ,Agronomy and Crop Science ,Ribosomal DNA ,Neofabraea - Abstract
California produces over 95% of the olives grown in the United States. In 2017, California’s total bearing acreage for olives was 14,570 hectares producing 192,000 tons of olives valued at $186.6 million. During the early spring of 2016, unusual leaf and shoot lesions were detected in olive trees from superhigh-density orchards in the Northern San Joaquin and Sacramento valleys of California. Affected trees displayed numerous leaf and shoot lesions developing at wounds created by mechanical harvesters. The ‘Arbosana’ cultivar was highly affected by the disease, whereas the disease was sporadic in ‘Arbequina’ and not found in ‘Koroneiki’ cultivar. Two fungal species, Neofabraea kienholzii and Phlyctema vagabunda, were found to be consistently associated with the disease, and Koch’s postulates were completed. Species identity was confirmed by morphology and molecular data of the partial large subunit rDNA, the internal transcribed spacer region, and partial beta-tubulin region. The disease signs and symptoms are described and illustrated.
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- 2019
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49. Characterization of Fusarium and Neocosmospora Species Associated With Crown Rot and Stem Canker of Pistachio Rootstocks in California
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Daniel P. Lawrence, M. T. Nouri, David Doll, Florent P. Trouillas, and M. Crespo
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0106 biological sciences ,0301 basic medicine ,Fusarium ,Canker ,biology ,Neocosmospora ,Crown (botany) ,food and beverages ,Plant Science ,030108 mycology & parasitology ,biology.organism_classification ,medicine.disease ,01 natural sciences ,03 medical and health sciences ,Horticulture ,medicine ,Rootstock ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
California produces 99.1% of pistachios grown in the United States, and diseases affecting pistachio rootstocks represent a constant challenge to the industry. Field surveys of fungi associated with pistachio rootstocks with symptoms of crown rot and stem canker in three central California counties followed by phylogenetic analyses of translation elongation factor 1-α and second largest subunit of RNA polymerase II gene fragments identified three Fusarium species (Fusarium equiseti, Fusarium oxysporum, and Fusarium proliferatum) and two Neocosmospora species (Neocosmospora falciformis and Neocosmospora solani). F. oxysporum and N. falciformis were the fungal species most frequently recovered from symptomatic pistachio trees. Inoculations of detached twigs of cultivar Kerman pistachio Pioneer Gold I and clonal University of California, Berkeley I (UCBI) rootstocks showed that all five species could colonize pistachio wood and cause vascular discolorations. Pathogenicity tests in potted pistachio trees completed Koch’s postulates and confirmed that F. oxysporum, F. proliferatum, N. falciformis, and N. solani were capable of producing rot and discoloration in stems of clonal UCBI rootstocks, the most widely planted pistachio rootstock in California. To our knowledge, this study is the first to present insights into the biodiversity and biology of Fusarium and Neocosmospora species associated with pistachio trees in California.
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- 2019
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50. Identification, Pathogenicity, and Spore Trapping of Colletotrichum karstii Associated with Twig and Shoot Dieback in California
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M. T. Nouri, Joey S Mayorquin, Craig E. Kallsen, Greg W. Douhan, Florent P. Trouillas, Beth B. Peacock, and Akif Eskalen
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Inoculation ,fungi ,food and beverages ,Virulence ,Plant Science ,Biology ,biology.organism_classification ,Pathogenicity ,Twig ,Spore ,Horticulture ,Colletotrichum ,Shoot ,Agronomy and Crop Science ,Clementine - Abstract
Colletotrichum Corda, 1831 species are well-documented pathogens of citrus that are associated with leaf and fruit anthracnose diseases. However, their role in twig and shoot dieback diseases of citrus has recently become more prominent. Recent surveys of orchards in the Central Valley of California have revealed C. gloeosporioides and a previously undocumented species, C. karstii, to be associated with twig and shoot dieback. Pathogenicity tests using clementine (cv. 4B) indicated that both C. karstii and C. gloeosporioides are capable of producing lesions following inoculation of citrus stems. Pathogenicity tests also revealed C. karstii to be the most aggressive fungal species producing the longest lesions after 15 months. The majority of spores trapped during this study were trapped during or closely following a precipitation event with the majority of spores being trapped from January through May. These findings confirm C. karstii as a new pathogen of citrus in California.
- Published
- 2019
- Full Text
- View/download PDF
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