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Morphological features of Peronospora apula. a, b conidiophores; c ultimate branchlets; d-h conidia; i-k oogonia and oospores. Sources: a, e-k WU 32410, holotype; b WU 32408; c, d WU 32409. Scale bars a, b 50 mm, c-k 20 mm. doi:10.1371/journal.pone.0096838.g002
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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...
Citations
... Of course, identification based on morphophysiological characteristics is considered an important factor, but these characteristics may require a lot of time in the study of Ph. infestans cultures and may cause difficulties in evaluating the non-phenotypically manifested external characteristics of genotypically changed species.Moleculargenetic identification of Ph. infestans started 30 years ago (Moller et al., 1993;Goodwin et al., 1999), then identification studies were continued based on internal transcribed spacer (ITS) rRNA and cytochrome oxidase genes of the fungal genome (Goodwin et al., 1999). It should be noted that comparing the ITS region of rRNA alone cannot fully analyze interspecies phylogenetic variation (Cooke et al., 2000;Voglmayr et al., 2014;Yang and Hong, 2018). When Phytophthora species were phylogenies with ITS, cox1, and cox2 genes, it was noted that the groups formed by cox1 and cox2 partial genes in the phylogenetic tree corresponded to each other.At the same time, although the main groups in the phylogenetic tree of cox2 genes with the ITS region are consistent, it has been noted that there are some variations (Martin and Tooley, 2003). ...
An isolate belonging to the genus Phytophthora was isolated from samples of infected potato plants in Uzbekistan. The morphological characteristics of the isolate were studied and the fungus Ph. infestans belonging to the type of oomycetes was determined. The colony of Phytophthora . sp isolate is colorless and the mycelium appears porous when growing. When studying the microscopic appearance, it was found that the hyphae are not septated, the width of the hypha is 2.5-4.4 μm, the width of the sporangium is 12-17 μm, and the length is 18-25 μm. It was found that P .infestans has amphigynous antheridium with oogonium and chlamydospores. To determine the exact phylogenetic status of this isolate, rRNA gene ITS region (845 bp) and cox2 (627 bp) gene were PCR amplified. The phylogeny of both marker genes showed that the isolate was Ph. Infestans and named Ph. infestans TVKT-1 due to its closeness to Ph. infestans species. The analysis of the ITS region of the rDNA gene as a barcode alone does not provide enough information for the identification of species belonging to the genus Phytophthora , for this, it is important to study the genetic analysis of oomycetes with the additional study of the cox2 gene. Compared to Phytophthora infestans species in the NCBI database, Ph. infestans TVKT-1, which we isolated, was found to have SNP mutations in the ITS region (16, 23, and 29 nucleotides) and cox2 gene (362, 364, and 365 nucleotides) nucleotide sequences.
... Analyses were restricted to the type host/a single host to avoid perpetuating potential errors in identification (e.g., the reports of Sclerophthora cryophila on Heteropogon contortus and Dichanthium annulatum [Farr and Rossman 2021] that are likely Peronosclerospora heteropogonis and Peronosclerospora dichanthiicola, respectively, which are species described after the initial reports were made) and potential pseudoreplication. Such an approach is justified because most phylogenetically defined downy mildew species have a narrow plant host range with either one host or a few closely related hosts (e.g., Choi et al. 2008Choi et al. , 2009aChoi et al. , 2009bChoi et al. , 2010Choi et al. , 2015Choi et al. , 2020Cunnington 2006;García-Blázquez et al. 2008;Görg et al. 2017;Petrželová et al. 2017;Rouxel et al. 2014;Runge and Thines 2012;Runge et al. 2011;Thines 2011;Thines and Choi 2016;Voglmayr et al. 2014b). Peronospora species infecting hosts in the Brassicales were considered to be members of Hyaloperonospora, even in the absence of formal transfers, based on the trends observed by Constantinescu and Fahtei (2002), Göker et al. (2003Göker et al. ( , 2004Göker et al. ( , 2009aGöker et al. ( , 2009b, Voglmayr et al. (2014a), andSalgado-Salazar et al. (2020). ...
There are approximately 700 obligate biotrophic species grouped into 20 genera (Oomycota, Peronosporaceae) that cause downy mildew diseases. In 2001, Dick hypothesized that diversification of downy mildew species was driven in part by host plant secondary metabolites. Dick further speculated that this was driven by the transition of host plants away from mycorrhizal associations or the evolution of C 4 photosynthesis. Specifically, loss of mycorrhizal associations or the use of C 4 photosynthesis would result in more free carbon that the plants could then use to produce more secondary metabolites. If true, then there should be more downy mildew species that infect hosts from plant lineages that lack mycorrhizal associations or use C 4 photosynthesis. However, analysis of 677 downy mildew species for host plant mycorrhizal associations and host plant photosynthetic pathway type shows that this is not what occurred. Seventy percent of downy mildew species parasitize hosts that form mycorrhizal associations, and 94% of downy mildew species parasitize hosts that use C 3 photosynthesis. From this, it is concluded that the diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C 4 photosynthesis. However, 85% of downy mildew species that parasitize Poaceae (grasses) parasitize C 4 hosts. Thus, it is possible that C 4 photosynthesis plays a role in the diversification of these genera.
[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2022.
... The assessment was guided by the results of published molecular phylogenetic analyses (e.g. Cunnington 2006;García-Blázquez et al., 2008;Choi et al., 2008, 2009a, 2009b, Choi et al., 2020Runge et al., 2011;Thines 2011;Sökücü and Thines 2014;Voglmayr et al., 2014;Runge and Thines 2012;Thines and Choi 2016;Görg et al., 2017;Petrželová et al., 2017) and population genetic analyses (Rouxel et al. 2013(Rouxel et al. , 2014Rivera et al., 2016a). For the assessment, it was assumed that a narrow species concept, based host plant identity, was appropriate for hypothesizing downy mildew species. ...
Downy mildew diseases caused by Peronosporaceae cause significant crop losses globally, with several emerging and resurgent threats in recent decades. Biodiversity data from digitized herbarium specimens provide an opportunity to develop a baseline census of species diversity, however, these resources may represent aggregations of nonrandom and opportunistic collecting efforts, which could lead to spurious results. Here, the MyCoPortal census of digitized herbarium records for downy mildew species collected from North America 1800 to present were analyzed. From 9838 unique records, 196 species were identified, reflecting ∼28% of known species diversity. Temporal and geographic collecting biases were observed, with 90% of the collections made prior to 1960 and the efforts of six “super-collectors” accounting for 25% of the collections. The presence of 50–100 undescribed species in North America was inferred from the records. Together, these results highlight the need for continued downy mildew collections, taxonomic research and digitization efforts.
... Forward and reverse sequences were merged and edited using Geneious 5.6 (Biomatters, Auckland, New Zealand). Reference sequences were obtained from the studies of Voglmayr (2003), Voglmayr et al. (2014), Voglmayr and Korytnianska (2015), and Thines et al. (2019). A complete list of all specimens and their NCBI sequence accession numbers is given in Table 1. ...
... This means, serial host jumping has to be demonstrated. In this study, a clade of Peronospora containing species mostly parasitic to Ranunculales was selected, based on unpublished genus wide investigations and phylogenies presented by Voglmayr (2003), Voglmayr et al. (2014), and Voglmayr and Korytnianska (2015). Within this clade, evidence for the pattern of serial host jumping could be found, supporting a critical element of the hypothesis of Thines (2019). ...
Biotrophic plant parasites cause economically important diseases, e.g. downy mildew of grape, powdery mildew of legumes, wheat stripe rust, and wheat bunt. But also in natural ecosystems, these organisms are abundant and diverse, and for many hosts more than one specialised biotrophic pathogen is known. However, only a fraction of their diversity is thought to have been described. There is accumulating evidence for the importance of host jumping for the diversification of obligate biotrophic pathogens but tracing this process along the phylogeny of the pathogens is often complicated by a lack of resolution of phylogenetic trees, low taxon and specimen sampling, or either too few or too many host jumps in the pathogen group in question. Here, a clade of Peronospora species mostly infecting members of the Ranunculales was investigated using multigene analyses and ancestral state reconstructions. These analyses show that this clade started out in Papaveraceae, with subsequent host jumps to Berberidaceae, Euphorbiaceae and Ranunculaceae. In Ranunculaceae, radiation to a variety of hosts took place, and a new host jump occurred to Caryophyllaceae. This highlights that host jumping and subsequent radiation is a key evolutionary process driving the diversification of Peronospora. It seems likely that the observed pattern can be generalised to other obligate parasite groups, as diverse hosts in unrelated families have also been reported for other pathogen groups, including powdery mildews, rust fungi, and smut fungi.
... Some cultivars are highly susceptible to the crown rot phase of the disease and thus die without giving rise to shoots (Coley-Smith, 1964). Unlike other downy mildew diseases caused by pathogens with a systemic phase (Gascuel et al., 2015;Voglmayr et al., 2014), hop plants with systemic infection of the root system may not have any foliar symptoms other than a general reduction in vigour. Susceptibility to the crown rot phase of the disease limits the cultivars that may be produced economically in environments favourable to the disease . ...
... Though planting resistant cultivars is a desirable strategy to control hop downy mildew, sources of resistance are rare and complete resistance has not been identified. Furthermore, differences in susceptibility of cultivars in different geographical locations to the crown rot and foliar phases of the disease complicates selection of tolerant cultivars (Woods & Gent, 2016 (Voglmayr et al., 2014). Leveraging knowledge of pathogen effectors for effector-assisted breeding to screen natural sources of resistance would help in efficiently identifying complete sources of resistance to downy mildew. ...
Pseudoperonospora humuli is an obligate biotrophic oomycete that causes downy mildew, one of the most devastating diseases of cultivated hop, Humulus lupulus. Downy mildew occurs in all production areas of the crop in the Northern Hemisphere and Argentina. The pathogen overwinters in hop crowns and roots, and causes considerable crop loss. Downy mildew is managed by sanitation practices, planting of resistant cultivars, and fungicide applications. However, the scarcity of sources of host resistance and fungicide resistance in pathogen populations complicates disease management. This review summarizes the current knowledge on the symptoms of the disease, life cycle, virulence factors, and management of hop downy mildew, including various forecasting systems available in the world. Additionally, recent developments in genomics and effector discovery, and the future prospects of using such resources in successful disease management are also discussed.
Taxonomy:
Class: Oomycota; Order: Peronosporales; Family: Peronosporaceae; Genus: Pseudoperonospora; Species: Pseudoperonospora humuli.
Disease symptoms:
The disease is characterized by systemically infected chlorotic shoots called "spikes". Leaf symptoms and signs include angular chlorotic lesions and profuse sporulation on the abaxial side of the leaf. Under severe disease pressure, dark brown discolouration or lesions are observed on cones. Infected crowns have brown to black streaks when cut open. Cultivars highly susceptible to crown rot may die at this phase of the disease cycle without producing shoots. However, foliar symptoms may not be present on plants with systemically infected root systems.
Infection process:
Pathogen mycelium overwinters in buds and crowns, and emerges on infected shoots in spring. Profuse sporulation occurs on infected tissues and sporangia are released and dispersed by air currents. Under favourable conditions, sporangia germinate and produce biflagellate zoospores that infect healthy tissue, thus perpetuating the infection cycle. Though oospores are produced in infected tissues, their role in the infection cycle is not defined.
Control:
Downy mildew on hop is managed by a combination of sanitation practices and timely fungicide applications. Forecasting systems are used to time fungicide applications for successful management of the disease. USEFUL WEBSITES: https://content.ces.ncsu.edu/hop-downy-mildew (North Carolina State University disease factsheet), https://www.canr.msu.edu/resources/michigan-hop-management-guide (Michigan Hop Management Guide), http://uspest.org/risk/models (Oregon State University Integrated Plant Protection Center degree-day model for hop downy mildew), https://www.usahops.org/cabinet/data/Field-Guide.pdf (Field Guide for Integrated Pest Management in Hops).
... 1 This plant is a member of genus papaver (papaveracea) which consists of 80 herbs and most famous one is Papaver somniferum, commonly known as opium poppy or bread-seed poppy belonging to the family papaveraceae. 2 Somniferous is a latin word meaning "sleep bringing". These are annual herbs that are usually grown as ornamental flowers in gardens almost anywhere. ...
Objective: To assess the trend of poppy use as folk remedy for children at Mardan and surroundings.
Study design: Cross-sectional observational study.
Duration and Place of Study: This study was carried out from August 2019 to January 2020 at Mardan.
Material and Methods: A door to door survey of 500 families residing in Mardan, was carried out. Eligible families/households (having 0 – 12 years aged children) were selected randomly from all these locations of Mardan. A pre-test structured questionnaire proforma was formulated which contained information about trend of using poppy parts (pods) as a remedy for children. Chi square was applied to analyze qualitative variables and independent T test was applied to analyse quantitative variables. P value less than 0.05 was considered significant.
Results: Total 500 questionnaires were filled. Out of these, 250 belonged to urban/city areas (group A) and 250 from rural areas (group B). Out of 250 urban families, 93 (37.2%) families used poppy for their children in comparison to 226 (90.4%) families of rural areas. The research showed significantly more use of poppy for children in rural areas as compared to urban areas (p=0.000). People used poppy primarily for treating cough. There was strong association between education status of parents, poppy use being significantly more in children of uneducated parents (p=0.000).
Conclusion: Poppy is commonly used by people as household remedy to treat cough, fever and crying babies as folk remedy. Its use is more in rural areas as compared to urban areas.
Key Words: Poppy, Cross-sectional, Survey, Therapy
... The combined use of nuclear and mitochondrial gene regions resulted in generally highly-resolved clades and no supported discordance between mitochondrial and nuclear loci was observed, which is in line with previous studies (Choi & Thines 2015, Choi et al. 2015a, and in contrast to the findings of a recent study on Peronosporaceae (Bourret et al. 2018). As previously shown, ITS data were highly similar for closely related species of Peronospora , Voglmayr et al. 2014, Choi et al. 2015b). In contrast, cox2 resolved most of the lineages that were found by the six-gene phylogeny and thus qualified as a suitable barcoding marker for Peronospora species (Choi et al. 2015b). ...
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 .
... However, there are a few downy mildew species that have broader host ranges, e.g. Pseudoperonospora cubensis Thines 2009, 2012;, Cohen et al. 2015, Bremia tulasnei (Choi and Thines 2015), Pe. somniferi (Voglmayr et al. 2014), and Pe. belbahrii . ...
Peronospora belbahrii is one of the most destructive downy mildew diseases that has emerged throughout the past two decades. Due to the lack of quarantine regulations and its possible seed-borne nature, it has spread globally and is now present in most areas in which basil is produced. While most obligate biotrophic, plant parasitic oomycetes are highly host-specific, there are a few that have a wider host range, e.g. Albugo candida , Bremia tulasnei , and Pseudoperonospora cubensis . Recently, it was shown that Peronospora belbahrii is able to infect Rosmarinus , Nepetia , and Micromeria in Israel in cross-infection trials, hinting an extended host range for also this pathogen. In this study, a newly occurring downy mildew pathogen on lavender was investigated with respect to its morphology and phylogeny, and it is shown that it belongs to Peronospora belbahrii as well. Thus, it seems that Peronospora belbahrii is currently extending its host range to additional members of the tribe Mentheae and Ocimeae. Therefore, it seems advisable to scrutinise all commonly used members of these tribes in order to avoid further spread of virulent genotypes.
... Thangavel, Wilson, Jones, Scott, & Voglmayr, 2016;Voglmayr, Montes-Borrego, & Landa, 2014). Since 2013, a second form of downy mildew has been found resulting from infection with Pe. somniferi that induces systemic symptoms distinct from the former and results in greater crop damage (Thangavel et al., 2016;Voglmayr et al., 2014). ...
... . Since 2013, a second form of downy mildew has been found resulting from infection with Pe. somniferi that induces systemic symptoms distinct from the former and results in greater crop damage (Thangavel et al., 2016;Voglmayr et al., 2014). Systemic infections are characterized by stunted growth of the poppy plants with chlorotic leaves associated with profuse sporulation in the abaxial leaf surface (Thangavel et al., 2016). ...
... In defining Pe. meconopsidis and Pe. somniferi, Voglmayr et al. (2014) noted that they were only associated with the hosts Meconopsidis cambrica, Pa. pavonium and Pa. ...
Opium poppy, belonging to the family Papaveraceae, is grown for its alkaloid compounds of pharmaceutical value. Downy mildew caused by Peronospora somniferi and Pe. meconopsidis, substantially impacts crop production. The present study was conducted to identify the host range of Pe. somniferi and Pe. meconopsidis within selected weed and ornamental members of the Papaveraceae family. Nine Papaver spp., Meconopsis cambrica and a nonhost control (tomato, Solanum lycopersicum) were challenged with both pathogens under controlled glasshouse or laboratory conditions using infested soil or foliar applied sporangia as inocula. Peronospora somniferi and Pe. meconopsidis induced disease symptoms, including sporulation, in at least one trial for all tested species except for Pa. atlanticum and tomato. Species‐specific PCR testing of foliage of challenged plants confirmed infections by both pathogen species of symptomatic plants, identifying these as hosts. Positive PCR tests were also obtained from Pa. atlanticum plants for both pathogens. However, in the absence of pathogen sporulation structures as further evidence of infection, the host status of Pa. atlanticum remains inconclusive. Testing of seeds collected from Pe. somniferi and Pe. meconopsidis infected plants of Pa. somniferum, Pa. dubium, Pa. rhoeas and Pa. nudicaule showed presence of both pathogens, indicating likely ability for seed transmission in these species. We identified new hosts of these pathogens and discuss potential implications of these alternative hosts in pathogen survival, dissemination and epidemic initiation.
... A hallmark of the genus Peronospora is the high degree of host specificity, which is usually on the plant species level (e.g. Voglmayr 2003;García-Blázquez et al. 2008;Thines et al. 2009;Thines and Kummer 2013;Voglmayr et al. 2014;Choi et al. 2015a). Downy mildew caused by Peronospora is observed in many plant families, and especially Ranunculaceae, Amaranthaceae, Caryophyllaceae, Fabaceae, Plantaginaceae and Lamiaceae have many reported host genera and species (Constantinescu 1991). ...
... The observation of the high degree of host specificity in downy mildews has led to the reappraisal of the species diversity in many downy mildew species complexes, often focussed on economically important groups (Choi et al. 2009(Choi et al. , 2015a(Choi et al. , 2018Thines et al. 2009Thines et al. , 2019Thines 2011;Voglmayr et al. 2014;Görg et al. 2017). The genus Peronospora harbours various species of economic impact, of which P. belbahrii ) and P. aquilegiicola ) are pathogens that have just recently emerged. ...
Peronospora aquilegiicola is a destructive pathogen of columbines and has wiped out most Aquilegia cultivars in several private and public gardens throughout Britain. The pathogen, which is native to East Asia was noticed in England and Wales in 2013 and quickly spread through the country, probably by infested plants or seeds. To our knowledge, the pathogen has so far not been reported from other parts of Europe. Here, we report the emergence of the pathogen in the northwest of Germany, based on morphological and phylogenetic evidence. As the pathogen was found in a garden in which no new columbines had been planted recently, we assume that the pathogen has already spread from its original point of introduction in Germany. This calls for an increased attention to the further spread of the pathogen and the eradication of infection spots to avoid the spread to naturally occurring columbines in Germany and to prevent another downy mildew from becoming a global threat, like Peronospora belbahrii and Plasmopara destructor, the downy mildews of basil and balsamines, respectively.
