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Marco Thines - One of the best experts on this subject based on the ideXlab platform.
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The only known white blister rust on a basal angiosperm is a member of the genus Albugo
Organisms Diversity & Evolution, 2018Co-Authors: Sebastian Ploch, Young Joon Choi, Marco ThinesAbstract:Rare pathogens on unusual hosts are often providing valuable insight into the evolution of the pathogen group concerned, but it is often challenging to obtain sequence data for these, as because only very few, often decades-old specimens are available. One such example is Albugo tropica , the white blister pathogen of a basal angiosperm in the genus Peperomia (Piperaceae). For this species, only two, more than 70 and over 120-year-old collections available. Here, sequence data for A . tropica are reported and phylogenetic reconstructions reveal it as the sister group to all other white blister rusts of the genus Albugo . Its isolated position is also reflected by several morphological differences to the other species of the genus, such as very thin-walled sporangia and almost smooth oospores. The isolated phylogenetic position of the pathogen and its host might indicate that it is a relict species trapped on its host. The sister-group relationship to all members of the genus Albugo s.str., which have been investigated using molecular phylogenetics, hints at the possibility, that Albugo might have originated in South America or Gondwana and has later radiated in the holarctic on members of the Brassicales.
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A new presumably widespread species of Albugo parasitic to Strigosella spp. (Brassicaceae)
Mycological Progress, 2013Co-Authors: Mohammad Reza Mirzaee, Sebastian Ploch, Fabian Runge, Sabine Telle, Lisa Nigrelli, Marco ThinesAbstract:White blister rust is one of the most common diseases in Brassicaceae. Recently, molecular approaches revealed that apart from Albugo candida , several other more specialized species of the genus are causing this disease on Brassicaceae and the diversity of this group still remains largely unexplored. All newly described species have so far been sampled only from a limited geographic range, except for Albugo species which followed their invasive host from Europe to other continents. In this study we show that a previously unknown species of Albugo is causing white blister rust disease on two species of Strigosella . This species can be distinguished from other species of the genus Albugo both by its phylogenetic position and its unique oospore ornamentation that might be an adaptation to the harsh environment of the host plants. As a consequence, Albugo arenosa is described and illustrated as a new species, so far known from Strigosella africana in Iran and Spain, and Strigosella brevipes in Iran. Apart from Albugo candida and Albugo lepidii , this is the third hitherto known species of Albugo s. str. with a confirmed native distribution range of several thousand kilometres.
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A new species of Pustula (Oomycetes, Albuginales) is the causal agent of sunflower white rust
Mycological Progress, 2012Co-Authors: Christoph Rost, Marco ThinesAbstract:White blister rust of sunflower is an emerging disease that is among the most important diseases in this crop in South Africa and has recently spread to Europe. For the genus Albugo , it has been demonstrated that species are mostly at least host genus specific and that several previously overlooked species are present on Brassicaceae. It thus seems likely that previously unrecognised species are also present in the genus Pustula . Based on previous phylogenetic reconstruction in combination with differences in oospore ornamentation, it is revealed that Pustula on sunflower, previously attributed to Pustula tragopogonis (syn. Albugo tragopogonis ), is distinct from Pustula on Tragopogon . Therefore, this pathogen is described as a new species, Pustula helianthicola . In addition, taxonomic observations revealed that Pustula tragopogonis is an incorrect name and is replaced by the new combination, Pustula obtusata .
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Obligate biotrophic pathogens of the genus Albugo are widespread as asymptomatic endophytes in natural populations of Brassicaceae
Molecular ecology, 2011Co-Authors: Sebastian Ploch, Marco ThinesAbstract:Mutualistic interactions of plants with true fungi are a well-known and widespread phenomenon, which includes mycorrhiza and non-mycorrhizal endophytes like species of Epichloe. Despite the fact that these organisms intrude into plants, neither strong defence reactions nor the onset of symptoms of disease can be observed in most or even all infested plants, in contrast to endophytic pathogens. Oomycetes are fungal-like organisms belonging to the kingdom Straminipila, which includes diatoms and seaweeds. Although having evolved many convergent traits with true fungi and occupying similar evolutionary niches, widespread oomycete endophytes are not known to date, although more than 500 endophytic pathogens, including species of the obligate biotrophic genus Albugo, have been described. Here, we report that oomycetes of the genus Albugo are widespread in siliques of natural host populations. A total of 759 plants, encompassing four genera with rare reports of white blister incidents and one with common incidents, were collected from 25 sites in Germany. Nested PCR with species-specific primers revealed that 5-27% of the hosts with rare disease incidence carried asymptomatic Albugo in their siliques, although only on a single plant of 583 individuals, an isolated pustule on a single leaf could be observed. Control experiments confirmed that these results were not because of attached spores, but because of endophytic mycelium. Vertical inheritance of oomycete infections has been reported for several plant pathogens, and it seems likely that in nature this way of transmission plays an important role in the persistence of asymptomatic endophytic Albugo species.
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A new perspective on the evolution of white blister rusts: Albugo s.str. (Albuginales; Oomycota) is not restricted to Brassicales but also present on Fabales
Organisms Diversity & Evolution, 2011Co-Authors: Young Joon Choi, Marco Thines, Hyeon-dong ShinAbstract:For almost all groups of pathogens, unusual and rare host species have been reported. Often, such associations are based on single or few collections only, which are frequently hard to access. Many of them later prove to be due to misidentification of the host, the pathogen, or both. Therefore, such reports are often disregarded, or treated anecdotally in taxonomic and phylogenetic studies, regardless of their potential importance to unravelling the evolution of the entire group. Concerning oomycete biotrophs there are several reports of unusual and rare hosts for hardly known pathogens. In the order Fabales, for example, a single species of Albugo , A. mauginii , was described as parasitic to Onobrychis crista - galli about 80 years ago, but not recorded again. All other confirmed members of Albugo s.str. are parasitic to representatives of the families Brassicaceae, Capparaceae, Cleomaceae, and Resedaceae in the order Brassicales. In the present study, molecular phylogenetic analysis of cox2 mtDNA sequences and morphological investigations on an original specimen confirmed the occurrence of a member of Albugo on Fabaceae hosts, with the characteristic thin wall of the secondary sporangia, which is almost uniform in thickness. In phylogenetic analyses the species results as embedded within Albugo s.str. Therefore, it is concluded that the natural host range of Albugo s.str. extends from Brassicales to Fabales via host jumping. Our results underscore that unrevised reports of pathogens from unusual hosts should be reconsidered carefully to obtain a more complete picture of pathogen diversity and evolution.
Eric Kemen - One of the best experts on this subject based on the ideXlab platform.
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A fungal member of the Arabidopsis thaliana phyllosphere antagonizes Albugo laibachii via a GH25 lysozyme.
eLife, 2021Co-Authors: Katharina Eitzen, Eric Kemen, Samuel Kroll, Priyamedha Sengupta, Gunther DoehlemannAbstract:Much like the ‘good bacteria’ that live in our guts, many microscopic organisms can co-exist with and even benefit the plants they live on. For instance, the yeast Moesziomyces bullatus ex Albugo (MbA for short) can shield the leaves of its plant host against white rust, a disease caused by the organism Albugo laibachii. Studies have started to unveil how the various microbes at the surface of leaves interact and regulate their own community, yet the genetic mechanisms at play are less well-known. To investigate these processes, Eitzen et al. examined the genes that were switched on when MbA cells were in contact with A. laibachii on a leaf. This experiment revealed a few gene candidates that were then deleted, one by one, in MbA cells. As a result, a gene emerged as being key to protect the plant from white rust. It produces an enzyme known as the GH25 hydrolase, which, when purified, could reduce A. laibachii infections on plant leaves. Bacteria, fungi and other related microorganisms cause many diseases which, like white rust, can severely affect crops. Chemical methods exist to prevent these infections but they can have many biological and ecological side effects. A solution inspired by natural interactions may be safer and more effective at managing plant diseases that affect valuable crops. Harnessing the interactions between microbes living on plants, and the GH25 enzyme, may offer better disease control.
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a fungal member of the arabidopsis thaliana phyllosphere antagonizes Albugo laibachii via a secreted lysozyme
bioRxiv, 2020Co-Authors: Eric Kemen, Samuel Kroll, Katharina Eitzen, Priyamedha Sengupta, Gunther DoehlemannAbstract:Abstract Plants are not only challenged by pathogenic organisms, but also colonized by commensal microbes. The network of interactions these microbes establish with their host and amongst each other is suggested to contribute to the immune responses of plants against pathogens. In wild Arabidopsis thaliana populations, the oomycete pathogen Albugo laibachii has been shown to play an influential role in structuring the leaf phyllosphere. We show that the epiphytic yeast Moesziomyces bullatus ex Albugo on Arabidopsis, a close relative of pathogenic smut fungi, is an antagonistic member of the A. thaliana phyllosphere, which reduces infection of A. thaliana by A. laibachii. Combination of transcriptome analysis, reverse genetics and protein characterization identified a GH25 hydrolase with lysozyme activity as the major effector of this microbial antagonism. Our findings broaden the understanding of microbial interactions within the phyllosphere, provide insights into the evolution of epiphytic basidiomycete yeasts and pave the way for the development of novel biocontrol strategies.
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Albugo imposed changes to tryptophan derived antimicrobial metabolite biosynthesis may contribute to suppression of non host resistance to phytophthora infestans in arabidopsis thaliana
BMC Biology, 2017Co-Authors: Ghanasyam Rallapalli, Henk-jan Schoonbeek, Volkan Çevik, Shuta Asai, David C Prince, Deyang Xu, Eric KemenAbstract:Plants are exposed to diverse pathogens and pests, yet most plants are resistant to most plant pathogens. Non-host resistance describes the ability of all members of a plant species to successfully prevent colonization by any given member of a pathogen species. White blister rust caused by Albugo species can overcome non-host resistance and enable secondary infection and reproduction of usually non-virulent pathogens, including the potato late blight pathogen Phytophthora infestans on Arabidopsis thaliana. However, the molecular basis of host defense suppression in this complex plant–microbe interaction is unclear. Here, we investigate specific defense mechanisms in Arabidopsis that are suppressed by Albugo infection. Gene expression profiling revealed that two species of Albugo upregulate genes associated with tryptophan-derived antimicrobial metabolites in Arabidopsis. Albugo laibachii-infected tissue has altered levels of these metabolites, with lower indol-3-yl methylglucosinolate and higher camalexin accumulation than uninfected tissue. We investigated the contribution of these Albugo-imposed phenotypes to suppression of non-host resistance to P. infestans. Absence of tryptophan-derived antimicrobial compounds enables P. infestans colonization of Arabidopsis, although to a lesser extent than Albugo-infected tissue. A. laibachii also suppresses a subset of genes regulated by salicylic acid; however, salicylic acid plays only a minor role in non-host resistance to P. infestans. Albugo sp. alter tryptophan-derived metabolites and suppress elements of the responses to salicylic acid in Arabidopsis. Albugo sp. imposed alterations in tryptophan-derived metabolites may play a role in Arabidopsis non-host resistance to P. infestans. Understanding the basis of non-host resistance to pathogens such as P. infestans could assist in development of strategies to elevate food security.
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Additional file 16: of Albugo-imposed changes to tryptophan-derived antimicrobial metabolite biosynthesis may contribute to suppression of non-host resistance to Phytophthora infestans in Arabidopsis thaliana
2017Co-Authors: David Prince, Eric Kemen, Ghanasyam Rallapalli, Henk-jan Schoonbeek, Volkan Çevik, Shuta Asai, Neftaly Cruz-mireles, Ariane Kemen, Khaoula BelhajAbstract:Albugo-infected 35S:DWF4 is less susceptible to P. infestans than Albugo-infected Col-0. (A–D) Fluorescence microscopy of the adaxial surface of water-sprayed Col-0 (A), water-sprayed 35S:DWF4 (B), Albugo-infected Col-0 (C) and Albugo-infected 35S:DWF4 (D) leaves. Leaves were sprayed with water or Albugo and subsequently inoculated (12 days post spraying) with 100 μL of 1 × 105 spores per mL P. infestans 88069td. Leaves were examined using fluorescence microscopy at 3 dpi. Red fluorescence denotes P.i. growth. Scale bars: 200 μm. Results shown are representative of three independent experiments. (E and F) Photographs of Albugo-infected Col-0 (E) and Albugo-infected 35S:DWF4 (F) leaves, infected as described above, were taken at 3 dpi. Scale bars: 5 mm. (G) Quantification of P. infestans biomass on Albugo infected Col-0 and 35S:DWF4 by qRT-PCR. Leaves were inoculated with 100 μL of 1 × 105 spores per mL P. infestans 88069td. DNA was extracted at 3 dpi and the proportion of P. infestans DNA to plant DNA determined using qRT-PCR. Open circles and bars denote means ± SE of three independent biological replicates with three technical replicates per biological replicate. Closed, black circles denote the individual data points. Different letters indicate significant differences (Welch two sample t-test) (P
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Additional file 22: of Albugo-imposed changes to tryptophan-derived antimicrobial metabolite biosynthesis may contribute to suppression of non-host resistance to Phytophthora infestans in Arabidopsis thaliana
2017Co-Authors: David Prince, Eric Kemen, Ghanasyam Rallapalli, Henk-jan Schoonbeek, Shuta Asai, Neftaly Cruz-mireles, Ariane Kemen, Volkan Ăevik, Khaoula BelhajAbstract:Benzo-(1,2,3)-thiadiazole-7-carbothioic acid (BTH) regulated genes during Albugo infection time course. Spreadsheet showing the expression of Arabidopsis BTH regulated genes during infection with Albugo. (XLSX 346 kb
Young Joon Choi - One of the best experts on this subject based on the ideXlab platform.
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The only known white blister rust on a basal angiosperm is a member of the genus Albugo
Organisms Diversity & Evolution, 2018Co-Authors: Sebastian Ploch, Young Joon Choi, Marco ThinesAbstract:Rare pathogens on unusual hosts are often providing valuable insight into the evolution of the pathogen group concerned, but it is often challenging to obtain sequence data for these, as because only very few, often decades-old specimens are available. One such example is Albugo tropica , the white blister pathogen of a basal angiosperm in the genus Peperomia (Piperaceae). For this species, only two, more than 70 and over 120-year-old collections available. Here, sequence data for A . tropica are reported and phylogenetic reconstructions reveal it as the sister group to all other white blister rusts of the genus Albugo . Its isolated position is also reflected by several morphological differences to the other species of the genus, such as very thin-walled sporangia and almost smooth oospores. The isolated phylogenetic position of the pathogen and its host might indicate that it is a relict species trapped on its host. The sister-group relationship to all members of the genus Albugo s.str., which have been investigated using molecular phylogenetics, hints at the possibility, that Albugo might have originated in South America or Gondwana and has later radiated in the holarctic on members of the Brassicales.
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A new perspective on the evolution of white blister rusts: Albugo s.str. (Albuginales; Oomycota) is not restricted to Brassicales but also present on Fabales
Organisms Diversity & Evolution, 2011Co-Authors: Young Joon Choi, Marco Thines, Hyeon-dong ShinAbstract:For almost all groups of pathogens, unusual and rare host species have been reported. Often, such associations are based on single or few collections only, which are frequently hard to access. Many of them later prove to be due to misidentification of the host, the pathogen, or both. Therefore, such reports are often disregarded, or treated anecdotally in taxonomic and phylogenetic studies, regardless of their potential importance to unravelling the evolution of the entire group. Concerning oomycete biotrophs there are several reports of unusual and rare hosts for hardly known pathogens. In the order Fabales, for example, a single species of Albugo , A. mauginii , was described as parasitic to Onobrychis crista - galli about 80 years ago, but not recorded again. All other confirmed members of Albugo s.str. are parasitic to representatives of the families Brassicaceae, Capparaceae, Cleomaceae, and Resedaceae in the order Brassicales. In the present study, molecular phylogenetic analysis of cox2 mtDNA sequences and morphological investigations on an original specimen confirmed the occurrence of a member of Albugo on Fabaceae hosts, with the characteristic thin wall of the secondary sporangia, which is almost uniform in thickness. In phylogenetic analyses the species results as embedded within Albugo s.str. Therefore, it is concluded that the natural host range of Albugo s.str. extends from Brassicales to Fabales via host jumping. Our results underscore that unrevised reports of pathogens from unusual hosts should be reconsidered carefully to obtain a more complete picture of pathogen diversity and evolution.
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white blister rust caused by Albugo candida on oilseed rape in korea
Plant Pathology Journal, 2011Co-Authors: Mi Jeong Park, Young Joon Choi, Ji Hyun Park, Hyeon-dong ShinAbstract:Oilseed rape, Brassica napus ssp. oleifera (DC.) Metzger, is grownworldwide for the production of vegetable oil for human consump-tion, animal feed, and biodiesel. In Korea, this crop has also beenused as an important vegetable by harvesting the leaves nilat e winteror early spring or by picking the main flowering shoots just beforethe first flowers open. Since May 2004, typical symptoms of whiteblister rust disease on oilseed rape have been continuously found inseveral localities of Korea. Leavesof infected plants had whitishs orimostly on the lower surfaces and reddish violet blotches on thecorresponding upper leaf surfaces (Fig. 1A-C). Representativesamples were deposited in the herbarium (KUS-F20204, F22717,F24893). Microscopic examination of the sori from fresh materials wasperformed under a DIC-light microscope (Zeiss AX10). Thegrouped sporangiophores were hyaline, clavate or cylindric, andmeasured 20−40×12−15 µm (Fig. 1D & E). The sporangia werearranged in basipetal chains, hyaline, globose to subglobose, withuniform wall thickness and measured 15 −22×12−19 µm (Fig. 1F).The primary sporangia were similar to the secondary sporangia,although the former exhibit a slightly thicker wall than the latter. Noresting organs were observed. Up to now, the white blister rustpathogen on oilseed rape has been considered Albugo candida or A.cruciferarum (cf. Farr and Rossman, 2010). Albugo cruciferarum isregarded as a synonym of A candida . (cf. Choiet al ., 2007). Based onthe morphological characteristics and the specific host plant, thecausal agent of this disease was identified as A. candida (Pers.)Kuntze (Choi et al., 2007).The amplification and sequencing of cox2 mtDNA and ITSrDNA were performed according to a method of Choi et al. (2006),and the resulting sequences were deposited in GenBank (Acc. No.DQ409817 and DQ409816, respectively). In cox2 mtDNA-basedphylogenetic analysis with Albugo s.str. sequences from GenBank(Fig. 2), the present causal agent formed a well-supported group withA. candida from Brassica juncea (AY927046) as well as variousbrassicaceous plants am, ong which no sequence difference was found.The sequence of ITS region was also identical to those of A. candidafrom B. oleracea (AF241767) and B. juncea (AY929828). Therefore,the sequence analysis verified the pathogen to be A. candida .In Korea, it has been reported that A. candida attacks B. junceaand B. campestris subsp. pekinensis (Korean Society of PlantPathology, 2009), but to our knowledge this is the first record of A.candida on oilseed rape. As the white blister rust caused by A.candida is one of the most devastating diseases of oilseed rape inmany countries where the crop is cultivated, the occurrence of thisdisease poses a significant threat for the commercial large-scalecultivation of oilseed rape in Korea.
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Morphological and molecular confirmation of Albugo resedae (Albuginales; Oomycota) as a distinct species from A. candida
Mycological Progress, 2011Co-Authors: Young Joon Choi, Marco ThinesAbstract:The genus Albugo s.str. causes white blister rust on four families of the Brassicales, Brassicaceae, Capparaceae, Cleomaceae, and Resedaceae. Recent phylogenetic studies have revealed that several host specific lineages are present within Albugo on Brassicales, while it was also confirmed that Albugo candida has an exceptionally wide host range which extends from Brassicaceae to Cleomaceae and Capparaceae. The Albugo species infecting the Resedaceae was attributed in monographic studies as well as local floras to either A. resedae or, applying a broader species concept, to A. candida . In the present study, A. resedae specimens were morphologically and molecularly compared to the five Albugo species so far confirmed from Brassicales, A. candida , A. koreana , A. laibachii , A. lepidii , and A. voglmayrii . Both morphological differences of oospore ornamentation and phylogenetic analysis of cox2 mtDNA sequences provided evidence that A. resedae is distinct from A. candida and from the additional four species so far described from Brassicaceae. It thus seems possible that so far unknown factors restrict Albugo candida to Brassicaceae and its sister families, Cleomaceae and Capparaceae.
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Three new phylogenetic lineages are the closest relatives of the widespread species Albugo candida.
Fungal biology, 2011Co-Authors: Young Joon Choi, Hyeon-dong Shin, Sebastian Ploch, Marco ThinesAbstract:White blister rust caused by the obligate biotroph Albugo candida (Albuginaceae; Oomycota) is one of the most notorious and common diseases of Brassicaceae. During the past 5 y, A. candida specimens collected from about 30 host genera were phylogenetically and morphologically investigated in several studies. These not only revealed that A. candida s.str. has a broad host range, encompassing a large number of host plants belonging to Brassicales, but also the presence of previously overlooked species of Albugo with hosts in this order. In this study, we examined specimens from Alyssum, Barbarea, and Rorippa, of which many species were commonly recorded as host plants of A. candida but could not be included in previous works due to the paucity of specimens available. It was revealed that Albugo specimens from Alyssum montanum, Barbarea vulgaris, and various Rorippa species, were placed in three phylogenetically distinct clades, but closer to A. candida s.str. than any previously reported species. Oospores were observed from Albugo specimens parasitic to Rorippa and could be distinguished morphologically from A. candida. Therefore, Albugo rorippae sp. nov. is described and illustrated here. In addition, a key of Albugo species described previously from Brassicales is given. The present study reveals that a large number of Albugo species remain still undiscovered, and that species close to A. candida exist. This could help elucidating the basis of the broad host range of A. candida as opposed to the narrow specialisation that is seemingly present in other species of Albugo on the Brassicaceae.
Hyeon-dong Shin - One of the best experts on this subject based on the ideXlab platform.
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A new perspective on the evolution of white blister rusts: Albugo s.str. (Albuginales; Oomycota) is not restricted to Brassicales but also present on Fabales
Organisms Diversity & Evolution, 2011Co-Authors: Young Joon Choi, Marco Thines, Hyeon-dong ShinAbstract:For almost all groups of pathogens, unusual and rare host species have been reported. Often, such associations are based on single or few collections only, which are frequently hard to access. Many of them later prove to be due to misidentification of the host, the pathogen, or both. Therefore, such reports are often disregarded, or treated anecdotally in taxonomic and phylogenetic studies, regardless of their potential importance to unravelling the evolution of the entire group. Concerning oomycete biotrophs there are several reports of unusual and rare hosts for hardly known pathogens. In the order Fabales, for example, a single species of Albugo , A. mauginii , was described as parasitic to Onobrychis crista - galli about 80 years ago, but not recorded again. All other confirmed members of Albugo s.str. are parasitic to representatives of the families Brassicaceae, Capparaceae, Cleomaceae, and Resedaceae in the order Brassicales. In the present study, molecular phylogenetic analysis of cox2 mtDNA sequences and morphological investigations on an original specimen confirmed the occurrence of a member of Albugo on Fabaceae hosts, with the characteristic thin wall of the secondary sporangia, which is almost uniform in thickness. In phylogenetic analyses the species results as embedded within Albugo s.str. Therefore, it is concluded that the natural host range of Albugo s.str. extends from Brassicales to Fabales via host jumping. Our results underscore that unrevised reports of pathogens from unusual hosts should be reconsidered carefully to obtain a more complete picture of pathogen diversity and evolution.
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white blister rust caused by Albugo candida on oilseed rape in korea
Plant Pathology Journal, 2011Co-Authors: Mi Jeong Park, Young Joon Choi, Ji Hyun Park, Hyeon-dong ShinAbstract:Oilseed rape, Brassica napus ssp. oleifera (DC.) Metzger, is grownworldwide for the production of vegetable oil for human consump-tion, animal feed, and biodiesel. In Korea, this crop has also beenused as an important vegetable by harvesting the leaves nilat e winteror early spring or by picking the main flowering shoots just beforethe first flowers open. Since May 2004, typical symptoms of whiteblister rust disease on oilseed rape have been continuously found inseveral localities of Korea. Leavesof infected plants had whitishs orimostly on the lower surfaces and reddish violet blotches on thecorresponding upper leaf surfaces (Fig. 1A-C). Representativesamples were deposited in the herbarium (KUS-F20204, F22717,F24893). Microscopic examination of the sori from fresh materials wasperformed under a DIC-light microscope (Zeiss AX10). Thegrouped sporangiophores were hyaline, clavate or cylindric, andmeasured 20−40×12−15 µm (Fig. 1D & E). The sporangia werearranged in basipetal chains, hyaline, globose to subglobose, withuniform wall thickness and measured 15 −22×12−19 µm (Fig. 1F).The primary sporangia were similar to the secondary sporangia,although the former exhibit a slightly thicker wall than the latter. Noresting organs were observed. Up to now, the white blister rustpathogen on oilseed rape has been considered Albugo candida or A.cruciferarum (cf. Farr and Rossman, 2010). Albugo cruciferarum isregarded as a synonym of A candida . (cf. Choiet al ., 2007). Based onthe morphological characteristics and the specific host plant, thecausal agent of this disease was identified as A. candida (Pers.)Kuntze (Choi et al., 2007).The amplification and sequencing of cox2 mtDNA and ITSrDNA were performed according to a method of Choi et al. (2006),and the resulting sequences were deposited in GenBank (Acc. No.DQ409817 and DQ409816, respectively). In cox2 mtDNA-basedphylogenetic analysis with Albugo s.str. sequences from GenBank(Fig. 2), the present causal agent formed a well-supported group withA. candida from Brassica juncea (AY927046) as well as variousbrassicaceous plants am, ong which no sequence difference was found.The sequence of ITS region was also identical to those of A. candidafrom B. oleracea (AF241767) and B. juncea (AY929828). Therefore,the sequence analysis verified the pathogen to be A. candida .In Korea, it has been reported that A. candida attacks B. junceaand B. campestris subsp. pekinensis (Korean Society of PlantPathology, 2009), but to our knowledge this is the first record of A.candida on oilseed rape. As the white blister rust caused by A.candida is one of the most devastating diseases of oilseed rape inmany countries where the crop is cultivated, the occurrence of thisdisease poses a significant threat for the commercial large-scalecultivation of oilseed rape in Korea.
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Three new phylogenetic lineages are the closest relatives of the widespread species Albugo candida.
Fungal biology, 2011Co-Authors: Young Joon Choi, Hyeon-dong Shin, Sebastian Ploch, Marco ThinesAbstract:White blister rust caused by the obligate biotroph Albugo candida (Albuginaceae; Oomycota) is one of the most notorious and common diseases of Brassicaceae. During the past 5 y, A. candida specimens collected from about 30 host genera were phylogenetically and morphologically investigated in several studies. These not only revealed that A. candida s.str. has a broad host range, encompassing a large number of host plants belonging to Brassicales, but also the presence of previously overlooked species of Albugo with hosts in this order. In this study, we examined specimens from Alyssum, Barbarea, and Rorippa, of which many species were commonly recorded as host plants of A. candida but could not be included in previous works due to the paucity of specimens available. It was revealed that Albugo specimens from Alyssum montanum, Barbarea vulgaris, and various Rorippa species, were placed in three phylogenetically distinct clades, but closer to A. candida s.str. than any previously reported species. Oospores were observed from Albugo specimens parasitic to Rorippa and could be distinguished morphologically from A. candida. Therefore, Albugo rorippae sp. nov. is described and illustrated here. In addition, a key of Albugo species described previously from Brassicales is given. The present study reveals that a large number of Albugo species remain still undiscovered, and that species close to A. candida exist. This could help elucidating the basis of the broad host range of A. candida as opposed to the narrow specialisation that is seemingly present in other species of Albugo on the Brassicaceae.
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Evolution of diversity in Albugo is driven by high host specificity and multiple speciation events on closely related Brassicaceae.
Molecular phylogenetics and evolution, 2010Co-Authors: Sebastian Ploch, Hyeon-dong Shin, Young Joon Choi, Christoph Rost, Edward E. Schilling, Marco ThinesAbstract:The Albuginaceae, responsible for white blister rust disease on various angiosperms, are obligate biotrophic oomycetes that are only distantly related to downy mildews (Peronosporaceae). Their diversity has been much underestimated during the past decades, mainly because of the paucity of morphological characters for species delimitation, which led to the application of a broad species concept. Recent phylogenetic analyses have revealed three new species within Albugo parasitic to Brassicaceae, but the overall evolution of these plant pathogens remains poorly understood. Especially the diversity of Albugo in various plant genera is almost completely unknown. Based on ITS and cox2 sequence data of 72 Albugo specimens, predominantly from herbarium archives, and focusing on the widespread genus Cardamine, a high degree of phylogenetic diversity was revealed in Albugo. In particular, the hypothesis that one host genus can be colonised by more than one white blister rust species is confirmed. In addition, it is revealed that there are hitherto overlooked lineages with close relationships to the generalist species Albugo candida. Evidence for at least three different species of Albugo infecting Cardamine is presented in this study. Based on molecular phylogenetic and morphological data three new white blister rust species are described, Albugo hohenheimia, Albugo hesleri, and Albugo leimonios infecting Cardamine hirsuta, Cardamine diphylla and Cardamine pratensis, respectively. The fact that these species each have different ecological niches, suggests that environmental factors may have played a role in the speciation process in Albugo. Our findings suggest that other larger genera of the Brassicaceae may harbour unrecognized white blister rust species and that only a small fraction of the true biodiversity of white blister rusts is known at present.
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The host range of Albugo candida extends from Brassicaceae through Cleomaceae to Capparaceae
Mycological Progress, 2009Co-Authors: Hyeon-dong ShinAbstract:Capers ( Capparis spinosa ) are affected by white blister rust attributed to Albugo capparidis or, applying a broad species concept, to Albugo candida . Within the past 3 years, a great diversity within Albugo parasitic to the Brassicaceae has been observed. This has led to the description of two new specialized species within the parasites to Brassicaceae and the confirmation that Albugo lepidii is distinct from Albugo candida . In addition, it has been realized that Albugo candida has a broad host spectrum within the Brassicaceae, extending to the closely related Cleomaceae. Through molecular phylogenetic analysis of cox2 sequences and morphological comparison, it is demonstrated that the host range of A. candida extends to the Capparaceae. These findings are both relevant for practical plant pathology and raise questions regarding the mechanisms involved in the exceptional broad host range of Albugo candida , compared to other Albugo species.
Sebastian Ploch - One of the best experts on this subject based on the ideXlab platform.
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The only known white blister rust on a basal angiosperm is a member of the genus Albugo
Organisms Diversity & Evolution, 2018Co-Authors: Sebastian Ploch, Young Joon Choi, Marco ThinesAbstract:Rare pathogens on unusual hosts are often providing valuable insight into the evolution of the pathogen group concerned, but it is often challenging to obtain sequence data for these, as because only very few, often decades-old specimens are available. One such example is Albugo tropica , the white blister pathogen of a basal angiosperm in the genus Peperomia (Piperaceae). For this species, only two, more than 70 and over 120-year-old collections available. Here, sequence data for A . tropica are reported and phylogenetic reconstructions reveal it as the sister group to all other white blister rusts of the genus Albugo . Its isolated position is also reflected by several morphological differences to the other species of the genus, such as very thin-walled sporangia and almost smooth oospores. The isolated phylogenetic position of the pathogen and its host might indicate that it is a relict species trapped on its host. The sister-group relationship to all members of the genus Albugo s.str., which have been investigated using molecular phylogenetics, hints at the possibility, that Albugo might have originated in South America or Gondwana and has later radiated in the holarctic on members of the Brassicales.
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A new presumably widespread species of Albugo parasitic to Strigosella spp. (Brassicaceae)
Mycological Progress, 2013Co-Authors: Mohammad Reza Mirzaee, Sebastian Ploch, Fabian Runge, Sabine Telle, Lisa Nigrelli, Marco ThinesAbstract:White blister rust is one of the most common diseases in Brassicaceae. Recently, molecular approaches revealed that apart from Albugo candida , several other more specialized species of the genus are causing this disease on Brassicaceae and the diversity of this group still remains largely unexplored. All newly described species have so far been sampled only from a limited geographic range, except for Albugo species which followed their invasive host from Europe to other continents. In this study we show that a previously unknown species of Albugo is causing white blister rust disease on two species of Strigosella . This species can be distinguished from other species of the genus Albugo both by its phylogenetic position and its unique oospore ornamentation that might be an adaptation to the harsh environment of the host plants. As a consequence, Albugo arenosa is described and illustrated as a new species, so far known from Strigosella africana in Iran and Spain, and Strigosella brevipes in Iran. Apart from Albugo candida and Albugo lepidii , this is the third hitherto known species of Albugo s. str. with a confirmed native distribution range of several thousand kilometres.
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Obligate biotrophic pathogens of the genus Albugo are widespread as asymptomatic endophytes in natural populations of Brassicaceae
Molecular ecology, 2011Co-Authors: Sebastian Ploch, Marco ThinesAbstract:Mutualistic interactions of plants with true fungi are a well-known and widespread phenomenon, which includes mycorrhiza and non-mycorrhizal endophytes like species of Epichloe. Despite the fact that these organisms intrude into plants, neither strong defence reactions nor the onset of symptoms of disease can be observed in most or even all infested plants, in contrast to endophytic pathogens. Oomycetes are fungal-like organisms belonging to the kingdom Straminipila, which includes diatoms and seaweeds. Although having evolved many convergent traits with true fungi and occupying similar evolutionary niches, widespread oomycete endophytes are not known to date, although more than 500 endophytic pathogens, including species of the obligate biotrophic genus Albugo, have been described. Here, we report that oomycetes of the genus Albugo are widespread in siliques of natural host populations. A total of 759 plants, encompassing four genera with rare reports of white blister incidents and one with common incidents, were collected from 25 sites in Germany. Nested PCR with species-specific primers revealed that 5-27% of the hosts with rare disease incidence carried asymptomatic Albugo in their siliques, although only on a single plant of 583 individuals, an isolated pustule on a single leaf could be observed. Control experiments confirmed that these results were not because of attached spores, but because of endophytic mycelium. Vertical inheritance of oomycete infections has been reported for several plant pathogens, and it seems likely that in nature this way of transmission plays an important role in the persistence of asymptomatic endophytic Albugo species.
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Three new phylogenetic lineages are the closest relatives of the widespread species Albugo candida.
Fungal biology, 2011Co-Authors: Young Joon Choi, Hyeon-dong Shin, Sebastian Ploch, Marco ThinesAbstract:White blister rust caused by the obligate biotroph Albugo candida (Albuginaceae; Oomycota) is one of the most notorious and common diseases of Brassicaceae. During the past 5 y, A. candida specimens collected from about 30 host genera were phylogenetically and morphologically investigated in several studies. These not only revealed that A. candida s.str. has a broad host range, encompassing a large number of host plants belonging to Brassicales, but also the presence of previously overlooked species of Albugo with hosts in this order. In this study, we examined specimens from Alyssum, Barbarea, and Rorippa, of which many species were commonly recorded as host plants of A. candida but could not be included in previous works due to the paucity of specimens available. It was revealed that Albugo specimens from Alyssum montanum, Barbarea vulgaris, and various Rorippa species, were placed in three phylogenetically distinct clades, but closer to A. candida s.str. than any previously reported species. Oospores were observed from Albugo specimens parasitic to Rorippa and could be distinguished morphologically from A. candida. Therefore, Albugo rorippae sp. nov. is described and illustrated here. In addition, a key of Albugo species described previously from Brassicales is given. The present study reveals that a large number of Albugo species remain still undiscovered, and that species close to A. candida exist. This could help elucidating the basis of the broad host range of A. candida as opposed to the narrow specialisation that is seemingly present in other species of Albugo on the Brassicaceae.
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Evolution of diversity in Albugo is driven by high host specificity and multiple speciation events on closely related Brassicaceae.
Molecular phylogenetics and evolution, 2010Co-Authors: Sebastian Ploch, Hyeon-dong Shin, Young Joon Choi, Christoph Rost, Edward E. Schilling, Marco ThinesAbstract:The Albuginaceae, responsible for white blister rust disease on various angiosperms, are obligate biotrophic oomycetes that are only distantly related to downy mildews (Peronosporaceae). Their diversity has been much underestimated during the past decades, mainly because of the paucity of morphological characters for species delimitation, which led to the application of a broad species concept. Recent phylogenetic analyses have revealed three new species within Albugo parasitic to Brassicaceae, but the overall evolution of these plant pathogens remains poorly understood. Especially the diversity of Albugo in various plant genera is almost completely unknown. Based on ITS and cox2 sequence data of 72 Albugo specimens, predominantly from herbarium archives, and focusing on the widespread genus Cardamine, a high degree of phylogenetic diversity was revealed in Albugo. In particular, the hypothesis that one host genus can be colonised by more than one white blister rust species is confirmed. In addition, it is revealed that there are hitherto overlooked lineages with close relationships to the generalist species Albugo candida. Evidence for at least three different species of Albugo infecting Cardamine is presented in this study. Based on molecular phylogenetic and morphological data three new white blister rust species are described, Albugo hohenheimia, Albugo hesleri, and Albugo leimonios infecting Cardamine hirsuta, Cardamine diphylla and Cardamine pratensis, respectively. The fact that these species each have different ecological niches, suggests that environmental factors may have played a role in the speciation process in Albugo. Our findings suggest that other larger genera of the Brassicaceae may harbour unrecognized white blister rust species and that only a small fraction of the true biodiversity of white blister rusts is known at present.