Multigene phylogeny, taxonomy and reclassification of Hyaloperonospora on Cardamine

Abstract

Based on sequence data from cox1, cox2, ITS and LSU rDNA, it is shown that at least six species of Hyaloperonospora occur on the genus Cardamine, most of which were commonly classified under Peronospora dentariae. Based on sequences from their type hosts, Peronospora dentariae, Peronospora cardamines-laciniatae, Peronospora dentariae-macrophyllae, Peronospora malyi and Peronospora nasturtii-aquatici are combined into Hyaloperonospora, and their circumscription is clarified. Hyaloperonospora cardamines-enneaphyllos is described as a new species from Cardamine enneaphyllos. The host range of Hyaloperonospora nasturtii-aquatici, described from Nasturtium officinale, is shown to extend to various Cardamine species. Host range of species is shown to be highly diagnostic, with no overlap in their host range, but species commonly cannot be distinguished by morphology alone. Both cox1 and cox2 are confirmed to be good markers for phylogenetic species delimitation of closely related Hyaloperonospora species on Cardamine.

Diversity, Phylogeny, and Host-Specialization of Hyaloperonospora Species in Korea

“…Note: This cosmopolitan species is parasitic to four different species of Cardamine , including C. impatiens . The morphology fits well with the description of H. dentariae collected from C. heptaphylla [ 3 12 ], except for minor differences in the conidial size. In the cox 2 tree, as suggested by Voglmayr et al [ 12 ], there were a few subclades within “ H. dentariae complex”, among which the Korean samples formed a well-supported group ( Fig.…”

“…The Korean accessions collected from Cardamine impatiens fell within the H. dentariae clade, with weak supporting values in ITS dataset and the maximum value in cox 2 mtDNA. In the cox 2 dataset, they further formed their own well-supported subclade with the maximum supporting value in both analyses, as shown by Voglmayr et al [ 12 ], who observed the presence of host-specific substructures within the H. dentariae clade. Interestingly, there was a phylogenetic divergence between European and Korean accessions originating from the same plant, C. impatiens .…”

“…The concept has continued to the first monographic studies for the Peronosporaceae in Korea [ 19 ]. However, in keeping with the aforementioned taxonomic system for downy mildews, recent studies have certainly reflected the narrow species concept for Hyaloperonospora species parasitic to Cardamine [ 12 ] and Draba [ 11 ] in Korea ( Table 1 ).…”

“…A total of 140 names have been introduced to accommodate the Peronospora species infecting the brassicaceous plants [ 2 ], more than half of which have been described by Gäumann [ 3 4 ], who discriminated them mainly using subtle morphological difference and host specialization. In addition to the establishment of the new genus Hyaloperonospora for the brassicolous downy mildews (BDMs) [ 5 ], recent phylogenetic studies revealed a high level of species diversity and host-specialization of this genus [ 6 7 8 9 10 11 12 ]. The collective results support the view that the narrow species circumscription [ 3 4 ] better reflects the natural taxonomic system for BDMs.…”

Disentangling Peronospora on Papaver: Phylogenetics, Taxonomy, Nomenclature and Host Range of Downy Mildew of Opium Poppy (Papaver somniferum) and Related Species

“…[37], [47]–[63]), demonstrating that high biodiversity is commonly the result of high host specificity. Peronospora from Papaver are distributed amongst three clades (Figure 1), of which P. cristata from clade 1 is phylogenetically isolated from the other Peronospora species from Papaver , but clades 2 and 3 appear to be closely related (Figure 1).…”