Fig 3 - uploaded by Franz Oberwinkler
Content may be subject to copyright.
Heuristic maximum parsimony analysis of partial 28S rDNA of 47 Peronosporomycetes. Strict consensus of 264 most parsimonious trees. The topology was rooted with the group of the Peronosporomycetidae, as estimated in the phylogenetic analysis of a subset of sequences together with the sequence of a xanthophyte (see Fig. 1). *, species containing the insertion of 58 bp and the insertion of 7 bp; **, species containing only the insertion of 7 bp. Classification into orders and higher taxa according to Dick (1995). For details see text.
Source publication
To reveal phylogenetic relationships within the Peronosporomycetes (Oomycetes), we sequenced a part of the nuclear rDNA coding for the ribosomal large subunit of 46 Peronosporomycetes species and one representative of the Xanthophyta. The main emphasis of our study was put on the phylogenetic relationships within the Saprolegniomycetidae. We supple...
Contexts in source publication
Context 1
... maximum parsimony analysis found 264 most parsimonious trees with equal number of changes. The re- sulting strict consensus topology shown in Fig. 3 is very similar to the topology of the neighbor-joining analysis (Fig. 2). Mainly, the same groups are formed; differences can be found among the representatives of the order Lepto- mitales, which do not appear as a monophyletic group, and within the ...
Context 2
... the following, we will discuss the phylogenetic rela- tionships resulting from our analyses within the individual groups and compare them with the results obtained by other authors. For results of the neighbor-joining analysis, we shall always refer to Fig. 2 and for the results of the maxi- mum parsimony analysis to Fig. ...
Context 3
... to Dick (1995), three subclasses exist within the Peronosporomycetes: the Saprolegniomycetidae, Rhipid- iomycetidae, and Peronosporomycetidae. This classification is reflected in the topologies of our neighbor-joining and maximum parsimony analyses ( Figs. 1-3). The distribution of the detected insertions in the alignment (asterisks in Figs. 2 and 3) corresponds well with the adjacent position of Peronosporomycetidae, Rhipidiomycetidae, and Leptomi- tales in our analyses. In the topology in Fig. 2 the subclass Saprolegniomycetidae sensu Dick (1995) is only weakly sup- ported with a bootstrap value of 68%, whereas the mono- phyly of the Peronosporomycetidae is optimally supported with a bootstrap value of 100%. The representative of the Rhipidiomycetidae, Sapromyces elongatus (Cornu) Coker, appears on a separate branch in all three topologies (Figs. 1- 3). Our evaluations suggest, however, that the Rhipidiomy- cetidae are more closely related to the Saprolegniomycetidae than to the Peronosporomycetidae: the group consisting of Saprolegniomycetidae and Rhipidiomycetidae is optimally supported by a bootstrap value of 100% (Fig. 2), and this group appears in the maximum parsimony analysis as well (Fig. ...
Context 4
... the topology of the maximum parsimony analysis (Fig. 3), the two species of Pythium do not appear as a sepa- rate cluster together with Phytophthora undulata, but as rep- resentatives of basal groups of the Peronosporomycetidae (clusters 13a, 13b, and 13c). However, here as well, the other species of Phytophthora form a monophyletic group (cluster 12) together with the representatives of the Perono- sporales and hence support the results of the neighbor- joining analysis in this ...
Context 5
... 5 contains Achlya papillosa Humphrey, Achlya treleaseana (Humphrey) Kauffman, and Achlya spinosa de Bary, as well as Aplanes androgynus (Archer) Humphrey, Aplanopsis spinosa Dick, and Calyptralegnia achlyoides (Coker & Couch) Coker. This group is statistically well sup- ported by a bootstrap value of 96%. Many oogonia of the species of Achlya appearing in cluster 5 have an apiculus, in- cluding our isolate of Calyptralegnia achlyoides. Apiculi can be found in Aplanopsis spinosa and Aplanes androgynus as well. Dick (1995) considered the formation of an apiculus on the oogonium as a nonterminal differentiation of the oogonium, because a vegetative hypha is often present. He connected this phenomenon with the location where oogonia are formed; oogonia can be found in an intercalary position in many groups including the Pythiales, Saprolegniales, and Leptomitales. Hence, Dick (1995) did not consider the in- tercalary oogonia formation a good phylogenetic character. However, regarding the existence of apiculi in all the species of this cluster without considering the intercalary oogonia formation, this common character appears quite interesting here. The results of our analyses do not confirm the phenetic analysis by Powell and Blackwell (1998) in which Calyp- tralegnia and Aplanes occur in the same group as Brevi- legnia, Thraustotheca Humphrey, and Dictyuchus. In our analyses, the taxa Achlya treleaseana and Aplanes androgynus cluster in direct proximity together with Achlya papillosa, which points to a close relationship between the three taxa. This is very well supported by a bootstrap value of 100%. Moreover, the sequences of the examined DNA region were identical in Achlya treleaseana and Aplanes an- drogynus. The isolates of Aplanes androgynus examined by us very rarely have a basal papilla on their oogonia, whereas the whole oogonium of Achlya treleaseana is typically cov- ered with papillae. Interestingly, the oogonium of an isolate of Achlya treleaseana in Dick (1973, Plate 3, Fig. 37) is also portrayed with only one basal papilla. Since some represen- tatives of the genus Aplanes have already been transferred to the genera Saprolegnia or Achlya, Sparrow (1960) believed that it may be possible to dissolve the genus ...
Similar publications
To reveal phylogenetic relationships within the Peronosporomycetes (Oomycetes), we sequenced a part of the nuclear rDNA coding for the ribosomal large subunit of 46 Peronosporomycetes species and one representative of the Xanthophyta. The main emphasis of our study was put on the phylogenetic relationships within the Saprolegniomycetidae. We supple...
Citations
... Phytophthora was found to be closer related to Peronosporaceae than to Pythiales, which was confirmed in later studies (Dick et al., 1984;Riethmüller et al., 1999Riethmüller et al., , 2002Cooke et al., 2000;Hallin et al., 2018). Monophyly of the genera Pseudoperonospora and Hyaloperonospora were supported (Voglmayr, 2003). ...
... Molecular phylogenetic analyses showed a close phylogenetic relationship of downy mildews to the genus Phytophthora, suggesting an origin as a stem from different Phytophthora groups (Riethmüller et al., 1999;Cooke et al., 2000;Voglmayr, 2003). Later in a multigene (five genes) study Göker et al. found downy mildews to be monophyletic . ...
Plasmopara viticola (P. viticola, Berk. & M. A. Curtis; Berl. & De Toni) causing grapevine
downy mildew is one of the most damaging pathogens to viticulture worldwide. Since
its recognition in the middle of nineteenth century, this disease has spread from
America to Europe and then to all grapevine-growing countries, leading to significant
economic losses due to the lack of efficient disease control. In 1885 copper was found
to suppress many pathogens, and is still the most effective way to control downy
mildews. During the twentieth century, contact and penetrating single-site fungicides
have been developed for use against plant pathogens including downy mildews, but
wide application has led to the appearance of pathogenic strains resistant to these
treatments. Additionally, due to the negative environmental impact of chemical pesticides,
the European Union restricted their use, triggering a rush to develop alternative tools
such as resistant cultivars breeding, creation of new active ingredients, search for
natural products and biocontrol agents that can be applied alone or in combination
to kill the pathogen or mitigate its effect. This review summarizes data about the
history, distribution, epidemiology, taxonomy, morphology, reproduction and infection
mechanisms, symptoms, host-pathogen interactions, host resistance and control of the
P. viticola, with a focus on sustainable methods, especially the use of biocontrol agents.
... DNA extraction and amplification were performed according to using primer pairs ITS1/ITS4 (White, Bruns, Lee, & Taylor, 1990) for the internal transcribed spacer (ITS1-5.8S-ITS2) region, LR0R/LR6-O or LR0R/LR6 (Moncalvo, Wang, & Hseu, 1995;Riethmüller, Weiß, & Oberwinkler, 1999) for the 5′ terminal domain of the large subunit (LSU) of the nuclear ribosomal RNA gene (nrDNA), and primer-pairs FM80RC/FM85 (Martin & Tooley, 2003) and COXF4N/COXR4N (Kroon, Bakker, van den Bosch, Bonants, & Flier, 2004) for the mitochondrial cytochrome c oxidase subunit 1 (cox1). ITS was sequenced for all isolates while cox1 was sequenced for all isolates from new species and a representative set of isolates from known species of Phytophthora. ...
... (Levesque & DeCock 2004), but it is perfectly suited in the context of the Saprolegnia-Achlya clade. Deeper nodes appear most often unresolved by ITS, and there ribosomal genes are more useful and have been recommended for general oomycete phylogeny reconstruction (Riethmüller et al. 1999, Leclerc et al. 2000, Lara & Belbahri 2011). As the SSU rRNA gene is often used in environmental DNA surveys, it can be a potential source of discovery for new species by revealing the phylogenetic position of organisms whose existence was unsuspected (Fig. 2) and which can potentially be emerging parasites, or possibly also important ecological actors, as the ecological role of free-living oomycetes remains a largely uncharted territory (Lara & Belbahri 2011). ...
The Saprolegnia-Achlya clade comprises species of major environmental and economic importance due
to their negative impact on aquaculture and aquatic ecosystems by threatening fishes, amphibians, and crustaceans.
However, their taxonomy and phylogenetic relationships remain unresolved and suffer from many inconsistencies,
which is a major obstacle to the widespread application of molecular barcoding to identify pathogenic strains with
quarantine implications. We assessed phylogenetic relationships of major genera using three commonly used
markers (ITS, SSU rRNA, and LSU rRNA). A consensus tree of the three genes provided support for nine clades
encompassing eleven documented genera and a new clade (SAP1) that has not been described morphologically.
In the course of this study, we isolated a new species, Newbya dichotoma sp. nov., which provided the only culture
available for this genus. In parallel, we attempted to summarize the evolution of traits in the different genera, but
their successive reversals rendered the inference of ancestral states impossible. This highlights even more the
importance of a bar-coding strategy for saprolegniacean parasite detection and monitoring.
... These two genera have been placed together with Sclerophthora in the family Verrucalvaceae (Dick et al. 1984; Dick 2001) and together with the graminicolous downy mildew genera, Peronosclerospora and Sclerospora in the order Sclerosporales (Dick 2001 ). However, molecular phylogenetic analyses have revealed that the graminicolous downy mildews belong to the Peronosporaceae, while Ve rr u c al v u s and Pachymetra belong to the Saprolegniales, together with the genus Aphanomyces (Riethmüller et al. 1999; Göker et al. 2003; Thines et al. 2008 Thines et al. , 2009c; Telle and Thines, unpublished results). Aphanomyces has been shown to contain three major groups, one that is parasitic to animals, which includes also the causal agent of the crayfish plague, Aphanomyces astaci, one clade that contains saprophytes , and one clade that comprises the plant parasitic species of the genus (Diéguez-Uribeondo et al. 2009). ...
Oomycetes have colonised all continents and oceans in a great variety of habitats and are arguably one of the most successful eukaryotic lineages. This is contrasted by the limited knowledge available for this group in various fields in comparison to other ubiquitous eukaryotes, such as unikont fungi, animals or plants. In this review an overview is given on the evolution and diversification of the oomycetes, with focus on the plant parasitic lineages and aspects of wild pathosystems.
... Recent phylogenetic studies suggested that, in contrary to previously assumed (Daugherty et al., 1998), Aphanomyces and not Saprolegnia contains the most ancestral organisms of the Saprolegniales (Leclerc et al., 2000; Petersen and Rosendahl, 2000). Interestingly, phytopathogenic species of other genera, such as Pachymetra chaunorhiza (Verrucalvaceae) or Plectospira myriandra (Saprolegniaceae), clustered together with phytopathogenic or saprophytic Aphanomyces species, whereas the zoopathogenic A. laevis and A. astaci appeared on a different branch (Riethmuller et al., 1999; Leclerc et al., 2000). This suggests that the Aphanomyces genus radiated early, and allows to hypothesize that the ability of Aphanomyces to infect plants might be quite ancient and roots to the origin of the Peronosporomycetes. ...
... LSU had the lowest interspecific variation of the three markers (Fig. 2), and the use of LSU as an oomycete barcode does not always provide enough resolution for identification to the species level. LSU appears to be better suited for studying genus- and family-level relationships in oomycetes (Riethmüller et al. 1999, 2002; Petersen & Rosendahl 2000; Voglmayr & Riethmüller 2006). A large portion of LSU was used to provide sufficient variation but this precludes amplification and sequencing with a single pair of primers. ...
Oomycete species occupy many different environments and many ecological niches. The genera Phytophthora and Pythium for example, contain many plant pathogens which cause enormous damage to a wide range of plant species. Proper identification to the species level is a critical first step in any investigation of oomycetes, whether it is research driven or compelled by the need for rapid and accurate diagnostics during a pathogen outbreak. The use of DNA for oomycete species identification is well established, but DNA barcoding with cytochrome c oxidase subunit I (COI) is a relatively new approach that has yet to be assessed over a significant sample of oomycete genera. In this study we have sequenced COI, from 1205 isolates representing 23 genera. A comparison to internal transcribed spacer (ITS) sequences from the same isolates showed that COI identification is a practical option; complementary because it uses the mitochondrial genome instead of nuclear DNA. In some cases COI was more discriminative than ITS at the species level. This is in contrast to the large ribosomal subunit, which showed poor species resolution when sequenced from a subset of the isolates used in this study. The results described in this paper indicate that COI sequencing and the dataset generated are a valuable addition to the currently available oomycete taxonomy resources, and that both COI, the default DNA barcode supported by GenBank, and ITS, the de facto barcode accepted by the oomycete and mycology community, are acceptable and complementary DNA barcodes to be used for identification of oomycetes.
... We retain the name Oomycetes because of its wider currency in the mycological and plant pathological communities. Oomycetes are an ancient group, but their evolutionary history is mostly inferred from molecular phylogenetic studies of living species [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Bhattacharya et al. [17] suggested a mean age for the split between Oomycetes and Bacillariophyta of 936 Ma (range: 1150 -770 Ma). ...
Thin sections of petrified fossils made during the latter part of the nineteenth and early twentieth centuries to investigate the internal tissue systems of plants now provide an important new source of information on associated micro-organisms. We report a new heterokont eukaryote (Combresomyces williamsonii sp. nov.) based on exquisitely preserved fossil oogonia, antheridia and hyphae from the Carboniferous (Pennsylvanian: Bashkirian stage) of UK. The structure of the oogonia and antheridia and features observed within the hyphae demonstrate a relationship with Oomycetes (Peronosporomycetes). The fossil micro-organism was documented in situ in petrified stem cortex and rootlets of the extinct seed fern Lyginopteris oldhamia (Pteridospermales). The main observed features point towards a pythiaceous Oomycete but links to biotrophic Albuginales or Peronosporaceae cannot be ruled out owing to the observation of a possible haustorium. Our study provides the earliest evidence for parasitism in Oomycetes.
... The genus Aphanomyces appears to be the first lineage to diverge and the most ancestral group within the Saprolegniales (Oomycetes) (Petersen and Rosendhal, 2000;Leclerc et al., 2000). Previous molecular studies have shown that Aphanomyces occurs in a clade, which includes the following genera, Plectospyra (Petersen and Rosendhal, 2000;Leclerc et al., 2000), Pachymetra (Riethmüller et al., 1999Riethmüller et al., , 2002) and Leptolegnia (Hudspeth et al., 2000). Dick et al. (1999did not include any Aphanomyces isolates in their analysis of the Saprolegniaceae, and Dick (2001) placed Aphanomyces, together with Leptolegnia and Plectospyra in a newly created family of the Leptolegniaceae. ...
... A close relationship between Aphanomyces and Leptolegnia seemed to be supported in the cox2 phylogeny ofHudspeth et al. (2000). However, LSU-rDNA studies (Petersen and Rosendhal, 2000;Leclerc et al., 2000;Riethmüller et al., 1999Riethmüller et al., , 2002) support the hypothesis that Leptolegnia is more likely part of the crown Saprolegniaceae clade, while Aphanomyces still forms an early diverging basal clade, together with the soilborne genus Plectospira and the Poaceae root pathogen Pachymetra. Thus, it appears that Aphanomyces is a key phylogenetic intermediate between the Leptomitales sensu lato and the crown water moulds in the Saprolegniaceae sensu stricto (Dick et al., 1999;Riethmüller et al., 1999Riethmüller et al., , 2002) and is, in many ways, different from other genera of Saprolegniales, e.g., K-bodies of spores (Powell and Blackwell, 1995), oospore organization (Dick, 1995), wall chemistry (Petersen et al., 1996), and phylogenetically (Petersen et al., 1995;Leclerc et al., 2000). ...
... However, LSU-rDNA studies (Petersen and Rosendhal, 2000;Leclerc et al., 2000;Riethmüller et al., 1999Riethmüller et al., , 2002) support the hypothesis that Leptolegnia is more likely part of the crown Saprolegniaceae clade, while Aphanomyces still forms an early diverging basal clade, together with the soilborne genus Plectospira and the Poaceae root pathogen Pachymetra. Thus, it appears that Aphanomyces is a key phylogenetic intermediate between the Leptomitales sensu lato and the crown water moulds in the Saprolegniaceae sensu stricto (Dick et al., 1999;Riethmüller et al., 1999Riethmüller et al., , 2002) and is, in many ways, different from other genera of Saprolegniales, e.g., K-bodies of spores (Powell and Blackwell, 1995), oospore organization (Dick, 1995), wall chemistry (Petersen et al., 1996), and phylogenetically (Petersen et al., 1995;Leclerc et al., 2000). This genus comprises highly specialized parasitic species, some of which are among the most severe pathogens in both plants and animals (Papavizas and Ayers, 1974;Hatai et al., 1977;Dykstra et al., 1986;Cerenius and Söderhäll, 1992;Johnson and Seymour, 2002). ...
Beauveria bassiana is a facultative entomopathogen with an extremely broad host range that is used as a commercial biopesticide for the control of insects of agricultural, veterinary and medical significance. B. bassiana produces bassianolide, a cyclooligomer depsipeptide secondary metabolite. We have cloned the bbBsls gene of B. bassiana encoding a nonribosomal peptide synthetase (NRPS). Targeted inactivation of the B. bassiana genomic copy of bbBsls abolished bassianolide production, but did not affect the biosynthesis of beauvericin, another cyclodepsipeptide produced by the strain. Comparative sequence analysis of the BbBSLS bassianolide synthetase revealed enzymatic domains for the iterative synthesis of an enzyme-bound dipeptidol monomer intermediate from d-2-hydroxyisovalerate and l-leucine. Further BbBSLS domains are predicted to catalyze the formation of the cyclic tetrameric ester bassianolide by recursive condensations of this monomer. Comparative infection assays against three selected insect hosts established bassianolide as a highly significant virulence factor of B. bassiana.
... Recent phylogenetic studies suggested that, in contrary to previously assumed (Daugherty et al., 1998), Aphanomyces and not Saprolegnia contains the most ancestral organisms of the Saprolegniales (Leclerc et al., 2000; Petersen and Rosendahl, 2000). Interestingly, phytopathogenic species of other genera, such as Pachymetra chaunorhiza (Verrucalvaceae) or Plectospira myriandra (Saprolegniaceae), clustered together with phytopathogenic or saprophytic Aphanomyces species, whereas the zoopathogenic A. laevis and A. astaci appeared on a different branch (Riethmuller et al., 1999; Leclerc et al., 2000). This suggests that the Aphanomyces genus radiated early, and allows to hypothesize that the ability of Aphanomyces to infect plants might be quite ancient and roots to the origin of the Peronosporomycetes. ...
Aphanomyces euteiches is a Saprolegniale soilborne pathogen that infects various legumes,
notably pea (Pisum sativum) and alfalfa (Medicago sativa). A. euteiches was first described by
Jones and Drechsler in 1925, after an extensive survey conducted in 1924 to determine the
importance of various pea diseases in Wisconsin (USA). On this occasion, A. euteiches was
recognized as one of the most damaging pathogens on this crop (Jones and Linford, 1925). Since
then its impact has been considered in many legume-growing areas worldwide especially in regions
of alfalfa production in the USA. In this chapter we will first provide a glimpse of A. euteiches
biology and evolution, before giving an overview of the current knowledge on the diseases it causes
on legumes and the tools that could be used to combat it, with a focus on plant defenses and genetic
sources of resistance. In addition the first genomic resource available for this organism will be
presented with an emphasis on potential pathogenicity factors. Finally, research strategies and areas
of focus for future programs will be discussed in the concluding part of this chapter.
... Moreover, they can infect as primary parasites and as opportunists, which can grow wherever the epidermal barrier of a victim is broken (Leclerc et al. 2000). In general, it seems that parasitism in oomycetes has evolved independently several times, as it occurs in phylogenetically distinct lineages (Riethmuller et al. 1999). Both parasitic and saprobic strains can be found even within a single oomycete species. ...
We describe the infectivity, virulence, cultivating conditions, and phylogenetic positions of naturally occurring oomycete parasites of Daphnia, invertebrates which play a major role in aquatic food webs. Daphnia pulex individuals were found dead and covered by oomycete mycelia when exposed to pond sediments. We were able to extract 4 oomycete isolates from dead Daphnia and successfully cultivate them. Using the ITS and LSU rDNA sequences, we further showed these isolates to be distinct species. The isolates were experimentally demonstrated to be parasitic and not saprobic. After exposure to the parasites, Daphnia mortality was much higher than that reported for Daphnia infected with other known parasite species. Therefore, it is likely that oomycete parasites are important selective pressures in natural Daphnia populations. Moreover, their close phylogenetic relationship to parasites of fish and algae suggests that the stability of aquatic food webs (i.e. fish-Daphnia-algae) might be influenced by the shared parasite communities.
