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Blanca B. Landa - One of the best experts on this subject based on the ideXlab platform.
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Short communication: Local infection of opium poppy leaves by Peronospora somniferi sporangia can give rise to systemic infections and seed infection in resistant cultivars
Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, 2017Co-Authors: Miguel Montes-borrego, Rafael M. Jiménez-díaz, Francisco J. Muñoz-ledesma, Blanca B. LandaAbstract:Downy mildew (DM) of opium poppy (Papaver somniferum) caused by Peronospora somniferi is one of the most destructive diseases of this crop due to the systemic nature of infection as compared with local infections caused by Peronospora meconopsidis, the other downy mildew pathogen of this crop. We developed an inoculation method using Peronospora somniferi sporangia as inoculum and demonstrated for the first time that local infection of leaves by sporangia give rise to systemic infections in the plant as well as of seeds. Our results also showed that this inoculation protocol was very effective in reproducing disease symptoms and assessing the resistance response to DM in opium poppy genotypes under field conditions. More interestingly, results indicate that up to 100% of seed samples from some genotypes showing a complete (symptomless) resistant phenotype were infected by the pathogen when seeds were analyzed by a P. somniferi-specific nested-PCR protocol. This latter aspect deserves further attention while breeding opium poppy for resistance to P. somniferi
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Disentangling Peronospora on Papaver: Phylogenetics, Taxonomy, Nomenclature and Host Range of Downy Mildew of Opium Poppy (Papaver somniferum) and Related Species
PloS one, 2014Co-Authors: Hermann Voglmayr, Miguel Montes-borrego, Blanca B. LandaAbstract:Based on sequence data from ITS rDNA, cox1 and cox2, six Peronospora species are recognised as phylogenetically distinct on various Papaver species. The host ranges of the four already described species P. arborescens, P. argemones, P. cristata and P. meconopsidis are clarified. Based on sequence data and morphology, two new species, P. apula and P. somniferi, are described from Papaver apulum and P. somniferum, respectively. The second Peronospora species parasitizing Papaver somniferum, that was only recently recorded as Peronospora cristata from Tasmania, is shown to represent a distinct taxon, P. meconopsidis, originally described from Meconopsis cambrica. It is shown that P. meconopsidis on Papaver somniferum is also present and widespread in Europe and Asia, but has been overlooked due to confusion with P. somniferi and due to less prominent, localized disease symptoms. Oospores are reported for the first time for P. meconopsidis from Asian collections on Papaver somniferum. Morphological descriptions, illustrations and a key are provided for all described Peronospora species on Papaver. cox1 and cox2 sequence data are confirmed as equally good barcoding loci for reliable Peronospora species identification, whereas ITS rDNA does sometimes not resolve species boundaries. Molecular phylogenetic data reveal high host specificity of Peronospora on Papaver, which has the important phytopathological implication that wild Papaver spp. cannot play any role as primary inoculum source for downy mildew epidemics in cultivated opium poppy crops.
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real time pcr quantification of Peronospora arborescens the opium poppy downy mildew pathogen in seed stocks and symptomless infected plants
Plant Disease, 2011Co-Authors: Miguel Montesborrego, F J Munozledesma, Rafael M Jimenezdiaz, Blanca B. LandaAbstract:Montes-Borrego, M., Munoz-Ledesma, F. J., Jimenez-Diaz, R. M., and Landa, B. B. 2011. Real-time PCR quantification of Peronospora arborescens, the opium poppy downy mildew pathogen, in seed stocks and symptomless infected plants. Plant Dis. 95:143-152. In this study, we developed a reliable, quick, and accurate quantitative polymerase chain reaction (qPCR) assay based on the MIQE (Minimum Information for publication of Quantitative Real-Time PCR Experiments) guidelines for the quantification of Peronospora arborescens in infected downy mildew–symptomless opium poppy (Papaver somniferum) tissues and commercial seed stocks. The protocol was highly reproducible and allowed accurate quantification of pathogen DNA up to 10 fg in different plant DNA backgrounds without losing specificity and efficiency. Moreover, to further overcome difficulties conferred by the strict biotrophy of this pathogen, we developed dilution series of DNA extracted from a plasmid with the target pathogen DNA as a cloned insert. This facilitated the demonstration of the robustness of the protocol in different laboratories with different qPCR equipment and reagents, which may help in its use on a broad scale. Finally, we validated the usefulness of the qPCR protocol for quarantine purposes and downy mildew resistance screening by quantifying P. arborescens in complex, naturally infested opium poppy samples. Thus, a pathogen biomass of 0.0003 to 0.007‰ or of 0.110 to 5,557 ppm was quantified in symptomless capsules in commercial seed stocks, or in stem samples from symptomless opium poppy plants systemically infected by the pathogen, respectively.
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A Nested-Polymerase Chain Reaction Protocol for Detection and Population Biology Studies of Peronospora arborescens, the Downy Mildew Pathogen of Opium Poppy, Using Herbarium Specimens and Asymptomatic, Fresh Plant Tissues
Phytopathology, 2009Co-Authors: Miguel Montes-borrego, Francisco Javier Muñoz Ledesma, Rafael M. Jiménez-díaz, Blanca B. LandaAbstract:Montes-Borrego, M., Munoz Ledesma, F. J., Jimenez-Diaz, R. M., and Landa, B. B. 2009. A nested-polymerase chain reaction protocol for detection and population biology studies of Peronospora arborescens, the downy mildew pathogen of opium poppy, using herbarium specimens and asymptomatic, fresh plant tissues. Phytopathology 99:73-81. A sensitive nested-polymerase chain reaction (PCR) protocol was developed using either of two primer pairs that improves the in planta detection of Peronospora arborescens DNA. The new protocol represented an increase in sensitivity of 100- to 1,000-fold of detection of the oomycete in opium poppy tissue compared with the detection limit of single PCR using the same primer pairs. The new protocol allowed amplification of 5 to 0.5 fg of Peronospora arborescens DNA mixed with Papaver somniferum DNA. The protocol proved useful for amplifying Peronospora arborescens DNA from 96-year-old herbarium specimens of Papaver spp. and to demonstrate that asymptomatic, systemic infections by Peronospora arborescens can occur in wild Papaver spp. as well as in cultivated opium poppy. Also, the increase in sensitivity of the protocol made possible the detection of seedborne Peronospora arborescens in commercial opium poppy seed stocks in Spain with a high frequency, which poses a threat for pathogen spread. Direct sequencing of purified amplicons allowed alignment of a Peronospora arborescens internal transcribed spacer (ITS) ribosomal DNA (rDNA) sequence up to 730-bp long when combining the sequences obtained with the two primer sets. Maximum parsimony analysis of amplified Peronospora arborescens ITS rDNA sequences from specimens of Papaver dubium, P. hybridum, P. rhoeas, and P. somniferum from different countries indicated for the first time that a degree of host specificity may exist within populations of Peronospora arborescens. The reported protocol will be useful for epidemiological and biogeographical studies of downy mildew diseases as well as to unravel misclassification of Peronospora arborescens and Peronospora cristata, the reported causal agents of the opium poppy downy mildew disease.
Marco Thines - One of the best experts on this subject based on the ideXlab platform.
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Peronospora kuewa sp nov a new downy mildew species infecting the endangered hawaiian plant plantago princeps var princeps
Mycologia, 2021Co-Authors: Marco Thines, William J Davis, Jordie R Ocenar, M K Romberg, Jo Anne CrouchAbstract:Plantago princeps var. princeps is an endangered native Hawaiian plant, and part of the recovery plan includes repopulation using plants grown in a nursery. However, disease pressure from downy mildew is hindering repopulation efforts. The organism associated with the downy mildew was determined to be a Peronospora species with brown, ellipsoid conidia measuring 21 by 16 µm on average, which was morphologically different from validly described species of Peronospora that infect Plantago species, but it was morphologically similar to the invalidly published species Peronospora lanceolatae (Art. 40.1). Comparison of mitochondrial cytochrome oxidase subunit I (cox1), mitochondrial cytochrome oxidase subunit II (cox2), nuclear internal transcribed spacer (ITS), and nuclear 28S rRNA D1-D2 (28S) loci revealed the unknown Peronospora to be molecularly divergent from Peronospora alta and Peronsopora plantaginis, but very similar to Peronospora from Plantago lanceolata, the type host of P. lanceolatae. Phylogenetic trees inferred with maximum likelihood and Bayesian inference from a concatenated alignmaent and individual gene trees confirmed the divergence of the unknown Peronospora from P. alta and P. plantaginis and its similarity to P. lanceolatae. However, attempts to inoculate Plantago lanceolata with the strain from Plantago princeps var. princeps were unsuccessful, which, in conjunction with divergence in ITS, suggests that the unknown Peronospora is specific to Plantago princeps var. princeps. Herein, the Peronospora strain on Plantago princeps var. princeps is described as the new species Peronospora kuewa based on morphology, molecular phylogenetics, and host specificity. In addition, Peronospora gaponenkoae is described here to honor Nina Ivanova Gaponenko on the basis of her description of P. lanceolatae.
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Two new species of the Peronospora belbahrii species complex, Pe. choii sp. nov. and Pe. salviae-pratensis sp. nov., and a new host for Pe. salviae-officinalis.
Fungal systematics and evolution, 2020Co-Authors: Mascha Hoffmeister, S. Ashrafi, Marco Thines, Wolfgang MaierAbstract:The downy mildew species parasitic to Mentheae are of particular interest, as this tribe of Lamiaceae contains a variety of important medicinal plants and culinary herbs. Over the past two decades, two pathogens, Peronospora belbahrii and Pe. salviae-officinalis have spread globally, impacting basil and common sage production, respectively. In the original circumscription of Pe. belbahrii, the downy mildew of coleus (Plectranthus scutellarioides) was ascribed to this species in the broader sense, but subtle differences in morphological and molecular phylogenetic analyses using two genes suggested that this pathogen would potentially need to be assigned to a species of its own. In the present study, Peronospora species causing downy mildew on members of the Mentheae, including clary sage (Salvia sclarea), meadow sage (S. pratensis), basil (Ocimum basilicum), ground ivy (Glechoma hederacea) and coleus (Plectranthus scutellarioides) were studied using light microscopy and molecular phylogenetic analyses based on six loci (ITS rDNA, cox1, cox2, ef1a, hsp90 and β-tubulin) to clarify the species boundaries in the Pe. belbahrii species complex. The downy mildew on Salvia pratensis is shown to be distinct from Pe. salviae-officinalis and closely related to Pe. glechomae, and is herein described as a new species, Pe. salviae-pratensis. The downy mildew on S. sclarea was found to be caused by Pe. salviae-officinalis. This is of phytopathological importance, because meadow sage thus does not play a role as inoculum source for common sage in the natural habitat of the former in Europe and Asia, while clary sage probably does. The multi-gene phylogeny revealed that the causal agent of downy mildew on coleus is distinct from Pe. belbahrii on basil, and is herein described as a new taxon, Pe. choii.
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Peronospora aquilegiicola sp nov the downy mildew affecting columbines in the uk is an invasive species from east asia
European Journal of Plant Pathology, 2019Co-Authors: Marco Thines, Hyeon-dong Shin, Young Joon Choi, G Denton, Elizabeth J Beal, Anne Kilty, J O DentonAbstract:For diagnostics and control of emerging plant diseases, accurate species determination of the causal pathogens is a prerequisite. Downy mildew disease, caused by an unknown species of Peronospora, has speedily spread throughout numerous gardens and nurseries of the ornamental plant Aquilegia in the UK, but so far does not seem to have reached continental Europe. Apart from cultivated Aquilegia, downy mildew from wild columbines has only been reported from East Asia, where natural populations of Semiaquilegia are affected by downy mildew. To resolve the phylogenetic relationships of the causal pathogens on Aquilegia and Semiaquilegia, a phylogeny based on nine loci was performed. In addition, detailed morphological comparisons were carried out to determine if the downy mildew agents on Aquilegia and Semiaquilegia are conspecific and can be discriminated from related downy mildew species. Strong evidence was found that the downy mildew pathogens on Aquilegia and Semiaquilegia are conspecific, but distinct from other species of Peronospora affecting Ranunculaceae, Papaveraceae, and Saxifragaceae. Thus, a new species, Peronospora aquilegiicola, is introduced. The quick spread of the pathogen throughout the UK and the current absence from continental Europe highlights the importance to consider quarantine measures to restrict the further spread of this pathogen.
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the genome of Peronospora belbahrii reveals high heterozygosity a low number of canonical effectors and ct rich promoters
bioRxiv, 2019Co-Authors: Marco Thines, Rahul Sharma, Sander Y A Rodenburg, Anna Gogleva, Howard S Judelson, Xiaojuan Xia, Johan Van Den Hoogen, Miloslav Kitner, Joel Klein, Manon NeilenAbstract:Along with Plasmopara destructor, Peronosopora belbahrii has arguably been the economically most important newly emerging downy mildew pathogen of the past two decades. Originating from Africa, it has started devastating basil production throughout the world, most likely due to the distribution of infested seed material. Here we present the genome of this pathogen and results from comparisons of its genomic features to other oomycetes. The assembly of the nuclear genome was ca. 35.4 Mbp in length, with an N50 scaffold length of ca. 248 kbp and an L50 scaffold count of 46. The circular mitochondrial genome consisted of ca. 40.1 kbp. From the repeat-masked genome 9049 protein-coding genes were predicted, out of which 335 were predicted to have extracellular functions, representing the smallest secretome so far found in Peronosporalean oomycetes. About 16 % of the genome consists of repetitive sequences, and based on simple sequence repeat regions, we provide a set of microsatellites that could be used for population genetic studies of Pe. belbahrii. Peronospora belbahrii has undergone a high degree of convergent evolution, reflecting its obligate biotrophic lifestyle. Features of its secretome, signalling networks, and promoters are presented, and some patterns are hypothesised to reflect the high degree of host specificity in Peronospora species. In addition, we suggest the presence of additional virulence factors apart from classical effector classes that are promising candidates for future functional studies.
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HyaloPeronospora erucae sp. nov. (Peronosporaceae;Oomycota), the downy mildew pathogen of arugula(Eruca sativa)
European Journal of Plant Pathology, 2017Co-Authors: Young Joon Choi, Julia Kruse, Marco ThinesAbstract:Arugula (or rocket; Eruca sativa) is a popular leafy vegetable often used as a salad. Downy mildew disease poses a major threat to the cultivation of this crop. Along with a quick expansion of the cultivated land of arugula, significant losses due to this disease are continuously reported worldwide. Previous studies have attributed arugula downy mildew to HyaloPeronospora parasitica (previously classified under Peronospora), applying a broad species concept, or to Peronospora erucastri, but the identity of that the causal agent is still unproven. Based on both morphology and molecular phylogeny, the arugula pathogen is revealed to be distinct from the above two species in the current study. Consequently, HyaloPeronospora erucae sp. nov. is described and illustrated, and P. erucastri affecting Erucastrum spp. is transferred to the genus HyaloPeronospora as H. erucastri comb. nov., based on morphology and phylogenetic position.
Young Joon Choi - One of the best experts on this subject based on the ideXlab platform.
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Peronospora aquilegiicola sp nov the downy mildew affecting columbines in the uk is an invasive species from east asia
European Journal of Plant Pathology, 2019Co-Authors: Marco Thines, Hyeon-dong Shin, Young Joon Choi, G Denton, Elizabeth J Beal, Anne Kilty, J O DentonAbstract:For diagnostics and control of emerging plant diseases, accurate species determination of the causal pathogens is a prerequisite. Downy mildew disease, caused by an unknown species of Peronospora, has speedily spread throughout numerous gardens and nurseries of the ornamental plant Aquilegia in the UK, but so far does not seem to have reached continental Europe. Apart from cultivated Aquilegia, downy mildew from wild columbines has only been reported from East Asia, where natural populations of Semiaquilegia are affected by downy mildew. To resolve the phylogenetic relationships of the causal pathogens on Aquilegia and Semiaquilegia, a phylogeny based on nine loci was performed. In addition, detailed morphological comparisons were carried out to determine if the downy mildew agents on Aquilegia and Semiaquilegia are conspecific and can be discriminated from related downy mildew species. Strong evidence was found that the downy mildew pathogens on Aquilegia and Semiaquilegia are conspecific, but distinct from other species of Peronospora affecting Ranunculaceae, Papaveraceae, and Saxifragaceae. Thus, a new species, Peronospora aquilegiicola, is introduced. The quick spread of the pathogen throughout the UK and the current absence from continental Europe highlights the importance to consider quarantine measures to restrict the further spread of this pathogen.
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HyaloPeronospora erucae sp. nov. (Peronosporaceae;Oomycota), the downy mildew pathogen of arugula(Eruca sativa)
European Journal of Plant Pathology, 2017Co-Authors: Young Joon Choi, Julia Kruse, Marco ThinesAbstract:Arugula (or rocket; Eruca sativa) is a popular leafy vegetable often used as a salad. Downy mildew disease poses a major threat to the cultivation of this crop. Along with a quick expansion of the cultivated land of arugula, significant losses due to this disease are continuously reported worldwide. Previous studies have attributed arugula downy mildew to HyaloPeronospora parasitica (previously classified under Peronospora), applying a broad species concept, or to Peronospora erucastri, but the identity of that the causal agent is still unproven. Based on both morphology and molecular phylogeny, the arugula pathogen is revealed to be distinct from the above two species in the current study. Consequently, HyaloPeronospora erucae sp. nov. is described and illustrated, and P. erucastri affecting Erucastrum spp. is transferred to the genus HyaloPeronospora as H. erucastri comb. nov., based on morphology and phylogenetic position.
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evolution diversity and taxonomy of the Peronosporaceae with focus on the genus Peronospora
Phytopathology, 2016Co-Authors: Marco Thines, Young Joon ChoiAbstract:Downy mildews are a notorious group of oomycete plant pathogens, causing high economic losses in various crops and ornamentals. The most species-rich genus of oomycetes is the genus Peronospora. This review provides a wide overview of these pathogens, ranging from macro- and micro-evolutionary patterns, their biodiversity and ecology to short overviews for the currently economically most important pathogens and potential emerging diseases. In this overview, the taxonomy of economically relevant species is also discussed, as the application of the correct names and species concepts is a prerequisite for effective quarantine regulations and phytosanitary measures.
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multigene phylogeny taxonomy and reclassification of hyaloPeronospora on cardamine
Mycological Progress, 2014Co-Authors: Hermann Voglmayr, Young Joon Choi, Hyeon-dong ShinAbstract:Based on sequence data from cox1, cox2, ITS and LSU rDNA, it is shown that at least six species of HyaloPeronospora occur on the genus Cardamine, most of which were commonly classified under Peronospora dentariae. Based on sequences from their type hosts, Peronospora dentariae, Peronospora cardamines-laciniatae, Peronospora dentariae-macrophyllae, Peronospora malyi and Peronospora nasturtii-aquatici are combined into HyaloPeronospora, and their circumscription is clarified. HyaloPeronospora cardamines-enneaphyllos is described as a new species from Cardamine enneaphyllos. The host range of HyaloPeronospora nasturtii-aquatici, described from Nasturtium officinale, is shown to extend to various Cardamine species. Host range of species is shown to be highly diagnostic, with no overlap in their host range, but species commonly cannot be distinguished by morphology alone. Both cox1 and cox2 are confirmed to be good markers for phylogenetic species delimitation of closely related HyaloPeronospora species on Cardamine.
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mitochondrial phylogeny reveals intraspecific variation in Peronospora effusa the spinach downy mildew pathogen
Journal of Microbiology, 2011Co-Authors: Young Joon Choi, Marco Thines, Jae Gu Han, Hyeon-dong ShinAbstract:Since about two hundred years, downy mildew caused by Peronospora effusa is probably the most economically important disease of spinach (Spinacia oleracea). However, there is no information on the global phylogeographic structure of the pathogen and thus it is unclear whether a single genotype occurs worldwide or whether some local genetic variation exists. To investigate the genetic variability of this pathogen, a sequence analysis of two partial mitochondrial DNA genes, cox2 and nad1, was carried out. Thirty-three specimens of Peronospora effusa from four continents were analyzed, including samples from Australia, China, Japan, Korea, Mexico, Russia, Sweden, and the USA. Despite the potential anthropogenic admixture of genotypes, a phylogeographic pattern was observed, which corresponds to two major groups, an Asian/Oceanian clade and another group, which includes American/European specimens. Notably, two of six Japanese specimens investigated did not belong to the Asian/Oceanian clade, but were identical to three of the specimens from the USA, suggestive of a recent introduction from the USA to Japan. As similar introduction events may be occurring as a result of the globalised trade with plant and seed material, a better knowledge of the phylogeographic distribution of pathogens is highly warranted for food security purposes.
Hyeon-dong Shin - One of the best experts on this subject based on the ideXlab platform.
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Peronospora aquilegiicola sp nov the downy mildew affecting columbines in the uk is an invasive species from east asia
European Journal of Plant Pathology, 2019Co-Authors: Marco Thines, Hyeon-dong Shin, Young Joon Choi, G Denton, Elizabeth J Beal, Anne Kilty, J O DentonAbstract:For diagnostics and control of emerging plant diseases, accurate species determination of the causal pathogens is a prerequisite. Downy mildew disease, caused by an unknown species of Peronospora, has speedily spread throughout numerous gardens and nurseries of the ornamental plant Aquilegia in the UK, but so far does not seem to have reached continental Europe. Apart from cultivated Aquilegia, downy mildew from wild columbines has only been reported from East Asia, where natural populations of Semiaquilegia are affected by downy mildew. To resolve the phylogenetic relationships of the causal pathogens on Aquilegia and Semiaquilegia, a phylogeny based on nine loci was performed. In addition, detailed morphological comparisons were carried out to determine if the downy mildew agents on Aquilegia and Semiaquilegia are conspecific and can be discriminated from related downy mildew species. Strong evidence was found that the downy mildew pathogens on Aquilegia and Semiaquilegia are conspecific, but distinct from other species of Peronospora affecting Ranunculaceae, Papaveraceae, and Saxifragaceae. Thus, a new species, Peronospora aquilegiicola, is introduced. The quick spread of the pathogen throughout the UK and the current absence from continental Europe highlights the importance to consider quarantine measures to restrict the further spread of this pathogen.
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multigene phylogeny taxonomy and reclassification of hyaloPeronospora on cardamine
Mycological Progress, 2014Co-Authors: Hermann Voglmayr, Young Joon Choi, Hyeon-dong ShinAbstract:Based on sequence data from cox1, cox2, ITS and LSU rDNA, it is shown that at least six species of HyaloPeronospora occur on the genus Cardamine, most of which were commonly classified under Peronospora dentariae. Based on sequences from their type hosts, Peronospora dentariae, Peronospora cardamines-laciniatae, Peronospora dentariae-macrophyllae, Peronospora malyi and Peronospora nasturtii-aquatici are combined into HyaloPeronospora, and their circumscription is clarified. HyaloPeronospora cardamines-enneaphyllos is described as a new species from Cardamine enneaphyllos. The host range of HyaloPeronospora nasturtii-aquatici, described from Nasturtium officinale, is shown to extend to various Cardamine species. Host range of species is shown to be highly diagnostic, with no overlap in their host range, but species commonly cannot be distinguished by morphology alone. Both cox1 and cox2 are confirmed to be good markers for phylogenetic species delimitation of closely related HyaloPeronospora species on Cardamine.
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mitochondrial phylogeny reveals intraspecific variation in Peronospora effusa the spinach downy mildew pathogen
Journal of Microbiology, 2011Co-Authors: Young Joon Choi, Marco Thines, Jae Gu Han, Hyeon-dong ShinAbstract:Since about two hundred years, downy mildew caused by Peronospora effusa is probably the most economically important disease of spinach (Spinacia oleracea). However, there is no information on the global phylogeographic structure of the pathogen and thus it is unclear whether a single genotype occurs worldwide or whether some local genetic variation exists. To investigate the genetic variability of this pathogen, a sequence analysis of two partial mitochondrial DNA genes, cox2 and nad1, was carried out. Thirty-three specimens of Peronospora effusa from four continents were analyzed, including samples from Australia, China, Japan, Korea, Mexico, Russia, Sweden, and the USA. Despite the potential anthropogenic admixture of genotypes, a phylogeographic pattern was observed, which corresponds to two major groups, an Asian/Oceanian clade and another group, which includes American/European specimens. Notably, two of six Japanese specimens investigated did not belong to the Asian/Oceanian clade, but were identical to three of the specimens from the USA, suggestive of a recent introduction from the USA to Japan. As similar introduction events may be occurring as a result of the globalised trade with plant and seed material, a better knowledge of the phylogeographic distribution of pathogens is highly warranted for food security purposes.
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Reclassification of Two Peronospora Species Parasitic on Draba in HyaloPeronospora Based on Morphological and Molecular Phylogenetic Data
Mycopathologia, 2011Co-Authors: Young Joon Choi, Hyeon-dong Shin, Hermann VoglmayrAbstract:On the family Brassicaceae, the causal agent responsible for downy mildew disease was originally regarded as a single species, Peronospora parasitica (now under HyaloPeronospora ), but it was recently reconsidered to consist of many distinct species. In this study, 11 specimens of Peronospora drabae and P . norvegica parasitic on the genus Draba were investigated morphologically and molecularly. Pronounced differences in conidial sizes ( P. drabae : 14–20 × 12.5–15.5 μm; P. norvegica : 20–29 × 15.5–22 μm) and 7.8% sequence distance between their ITS1-5.8S-ITS2 rDNA sequences confirmed their status as distinct species. Based on ITS phylogeny and morphology (monopodially branching conidiophores, flexuous to sigmoid ultimate branchlets, hyaline conidia and lobate haustoria), the two species unequivocally belong to the genus HyaloPeronospora and not to Peronospora to which they were previously assigned. Therefore, two new combinations, HyaloPeronospora drabae and H. norvegica , are proposed. The two taxa are illustrated and compared using the type specimen for H. norvegica and authentic specimens for H. drabae , which is lectotypified.
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two novel Peronospora species are associated with recent reports of downy mildew on sages
Fungal Biology, 2009Co-Authors: Young Joon Choi, Hyeon-dong Shin, Marco ThinesAbstract:Recently, downy mildew of Salvia species became economically relevant globally, but the taxonomy of the causal agent remains still obscure. The objective of this study was to characterize and distinguish the different Peronospora species associated with downy mildew on sages, based on morphological and molecular data. For this purpose we compared Peronospora specimens on Salvia officinalis and Salvia plebeia with Peronospora swinglei, including the type specimen on Salvia reflexa. We observed that three Peronospora species are associated with downy mildew on sages, and the recent outbreak of the disease on S. officinalis and S. plebeia is associated with two undescribed species, contrasting the view that either P. swinglei or Peronospora lamii is the causal agent of the downy mildew disease as claimed previously by several studies. In the study presented here, we provide the formal descriptions and illustrations for the two newly introduced taxa, Peronospora salviae-plebeiae and Peronospora salviae-officinalis. The three species of Peronospora investigated seem to be restricted to specific species of Salvia: P. swinglei to S. reflexa, P. salviae-plebeiae to S. plebeia, and P. salviae-officinalis to S. officinalis. Speciation may be allopatric and closely linked to the geographic distributions of their host plants.
Hermann Voglmayr - One of the best experts on this subject based on the ideXlab platform.
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Peronospora odessana sp. nov., a downy mildew pathogen of a Tertiary relict species, Gymnospermium odessanum
Mycological Progress, 2015Co-Authors: Hermann Voglmayr, Victoria G. KorytnianskaAbstract:A new species of Peronospora is described from Gymnospermium odessanum , a rare spring geophyte considered a Tertiary relict in the northwestern Black Sea region of Ukraine, Moldova and Romania. Phylogenetic analyses based on a combined matrix of the internal transcribed spacer-large subunit (ITS-LSU) ribosomal DNA (rDNA) and the mitochondrial cytochrome c oxidase subunit 1 ( cox1 ) and cox2 genes demonstrate that it is a clearly distinct undescribed species. Morphological descriptions and illustrations of its oospores, conidiophores and conidia are provided. Despite its distinctive disease symptoms, the species has remained undetected until now, probably due to the rarity of its host. Peronospora odessana is the second species from Berberidaceae and is morphologically clearly distinct from P. achlydis on Achlys japonicus . The closest relatives of P. odessana were not revealed, but it is closely related to Peronospora bulbocapni , P. dicentrae and P. chrysosplenii , the hosts of which are also spring geophytes. Sequence data confirm that cox1 and cox2 are good barcoding loci; they show a similar number of nucleotide differences to its closest relatives.
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Disentangling Peronospora on Papaver: Phylogenetics, Taxonomy, Nomenclature and Host Range of Downy Mildew of Opium Poppy (Papaver somniferum) and Related Species
PloS one, 2014Co-Authors: Hermann Voglmayr, Miguel Montes-borrego, Blanca B. LandaAbstract:Based on sequence data from ITS rDNA, cox1 and cox2, six Peronospora species are recognised as phylogenetically distinct on various Papaver species. The host ranges of the four already described species P. arborescens, P. argemones, P. cristata and P. meconopsidis are clarified. Based on sequence data and morphology, two new species, P. apula and P. somniferi, are described from Papaver apulum and P. somniferum, respectively. The second Peronospora species parasitizing Papaver somniferum, that was only recently recorded as Peronospora cristata from Tasmania, is shown to represent a distinct taxon, P. meconopsidis, originally described from Meconopsis cambrica. It is shown that P. meconopsidis on Papaver somniferum is also present and widespread in Europe and Asia, but has been overlooked due to confusion with P. somniferi and due to less prominent, localized disease symptoms. Oospores are reported for the first time for P. meconopsidis from Asian collections on Papaver somniferum. Morphological descriptions, illustrations and a key are provided for all described Peronospora species on Papaver. cox1 and cox2 sequence data are confirmed as equally good barcoding loci for reliable Peronospora species identification, whereas ITS rDNA does sometimes not resolve species boundaries. Molecular phylogenetic data reveal high host specificity of Peronospora on Papaver, which has the important phytopathological implication that wild Papaver spp. cannot play any role as primary inoculum source for downy mildew epidemics in cultivated opium poppy crops.
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multigene phylogeny taxonomy and reclassification of hyaloPeronospora on cardamine
Mycological Progress, 2014Co-Authors: Hermann Voglmayr, Young Joon Choi, Hyeon-dong ShinAbstract:Based on sequence data from cox1, cox2, ITS and LSU rDNA, it is shown that at least six species of HyaloPeronospora occur on the genus Cardamine, most of which were commonly classified under Peronospora dentariae. Based on sequences from their type hosts, Peronospora dentariae, Peronospora cardamines-laciniatae, Peronospora dentariae-macrophyllae, Peronospora malyi and Peronospora nasturtii-aquatici are combined into HyaloPeronospora, and their circumscription is clarified. HyaloPeronospora cardamines-enneaphyllos is described as a new species from Cardamine enneaphyllos. The host range of HyaloPeronospora nasturtii-aquatici, described from Nasturtium officinale, is shown to extend to various Cardamine species. Host range of species is shown to be highly diagnostic, with no overlap in their host range, but species commonly cannot be distinguished by morphology alone. Both cox1 and cox2 are confirmed to be good markers for phylogenetic species delimitation of closely related HyaloPeronospora species on Cardamine.
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Reclassification of Two Peronospora Species Parasitic on Draba in HyaloPeronospora Based on Morphological and Molecular Phylogenetic Data
Mycopathologia, 2011Co-Authors: Young Joon Choi, Hyeon-dong Shin, Hermann VoglmayrAbstract:On the family Brassicaceae, the causal agent responsible for downy mildew disease was originally regarded as a single species, Peronospora parasitica (now under HyaloPeronospora ), but it was recently reconsidered to consist of many distinct species. In this study, 11 specimens of Peronospora drabae and P . norvegica parasitic on the genus Draba were investigated morphologically and molecularly. Pronounced differences in conidial sizes ( P. drabae : 14–20 × 12.5–15.5 μm; P. norvegica : 20–29 × 15.5–22 μm) and 7.8% sequence distance between their ITS1-5.8S-ITS2 rDNA sequences confirmed their status as distinct species. Based on ITS phylogeny and morphology (monopodially branching conidiophores, flexuous to sigmoid ultimate branchlets, hyaline conidia and lobate haustoria), the two species unequivocally belong to the genus HyaloPeronospora and not to Peronospora to which they were previously assigned. Therefore, two new combinations, HyaloPeronospora drabae and H. norvegica , are proposed. The two taxa are illustrated and compared using the type specimen for H. norvegica and authentic specimens for H. drabae , which is lectotypified.
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molecular taxonomy of phytopathogenic fungi a case study in Peronospora
PLOS ONE, 2009Co-Authors: Markus Goker, Hermann Voglmayr, Gema Garciablazquez, Teresa M Telleria, Maria P MartinAbstract:Background Inappropriate taxon definitions may have severe consequences in many areas. For instance, biologically sensible species delimitation of plant pathogens is crucial for measures such as plant protection or biological control and for comparative studies involving model organisms. However, delimiting species is challenging in the case of organisms for which often only molecular data are available, such as prokaryotes, fungi, and many unicellular eukaryotes. Even in the case of organisms with well-established morphological characteristics, molecular taxonomy is often necessary to emend current taxonomic concepts and to analyze DNA sequences directly sampled from the environment. Typically, for this purpose clustering approaches to delineate molecular operational taxonomic units have been applied using arbitrary choices regarding the distance threshold values, and the clustering algorithms. Methodology Here, we report on a clustering optimization method to establish a molecular taxonomy of Peronospora based on ITS nrDNA sequences. Peronospora is the largest genus within the downy mildews, which are obligate parasites of higher plants, and includes various economically important pathogens. The method determines the distance function and clustering setting that result in an optimal agreement with selected reference data. Optimization was based on both taxonomy-based and host-based reference information, yielding the same outcome. Resampling and permutation methods indicate that the method is robust regarding taxon sampling and errors in the reference data. Tests with newly obtained ITS sequences demonstrate the use of the re-classified dataset in molecular identification of downy mildews. Conclusions A corrected taxonomy is provided for all Peronospora ITS sequences contained in public databases. Clustering optimization appears to be broadly applicable in automated, sequence-based taxonomy. The method connects traditional and modern taxonomic disciplines by specifically addressing the issue of how to optimally account for both traditional species concepts and genetic divergence.